The Phenotype of Leber Congenital Amaurosis in Patients with AIPL1 Mutations

Home , AIPL1, NUB1, Retinitis pigmentosa, RPGRIP1

OPHTHALMIC MOLECULAR GENETICS

SECTION EDITOR: THADDEUS P. DRYJA, MD The Phenotype of Leber Congenital Amaurosis in Patients With AIPL1 Mutations

Sharola Dharmaraj, MD, FRCS; Bart P. Leroy, MD; Melanie M. Sohocki, PhD; Robert K. Koenekoop, MD, PhD; Isabelle Perrault, PhD; Khalid Anwar, MD; Shagufta Khaliq, PhD; R. Summathi Devi, MD; David G. Birch, PhD; Elaine De Pool, MD; Natalio Izquierdo, MD; Lionel Van Maldergem, MD; Mohammad Ismail, MD; Annette M. Payne, PhD; Graham E. Holder, PhD; Shomi S. Bhattacharya, PhD; Alan C. Bird, MD, FRCOphth; Josseline Kaplan, MD, PhD; Irene H. Maumenee, MD

Objectives: To describe the phenotype of Leber con- tion, were noted. Atrophic and/or pigmentary macular genital amaurosis (LCA) in 26 probands with muta- changes were present in 16 (80%) of 20 probands. Kera- tions in aryl hydrocarbon receptor interacting protein- toconus and cataracts were identified in 5 (26%) of 19 like 1 protein (AIPL1) and compare it with phenotypes patients, all of whom were homozygotes. The ERG of a of other LCA-related genes. To describe the electroreti- parent heterozygote carrier revealed significantly re- nogram (ERG) in heterozygote carriers. duced rod function, while ERGs for 6 other carrier parents were normal. Methods: Patients with AIPL1-related LCA were identified in a cohort of 303 patients with LCA by polymer- Conclusions: The phenotype of LCA in patients with ase chain reaction single-strand confirmational polymor- AIPL1 mutations is relatively severe, with a maculopa- phism mutation screening and/or direct sequencing. thy in most patients and keratoconus and cataract in a Phenotypic characterization included clinical and ERG large subset. Rod ERG abnormalities may be present in evaluation. Seven heterozygous carrier parents also un- heterozygous carriers of AIPL1 mutations. derwent ERG testing. Clinical Relevance: Understanding and recognizing the Results: Seventeen homozygotes and 9 compound het- phenotype of LCA may help in defining the course and erozygotes were identified. The W278X mutation was severity of the disease. Identifying the gene defect is the most frequent (48% of alleles). Visual acuities ranged from first step in preparation for therapy since molecular di- light perception to 20/400. Variable retinal appear- agnosis in LCA will mandate the choice of treatment. ances, ranging from near normal to varying degrees of chorioretinal atrophy and intraretinal pigment migra- Arch Ophthalmol. 2004;122:1029-1037

EBER CONGENITAL AMAURO- been reported.13-16 Currently, mutations in sis (LCA) was first de- 6 different retinal genes have been shown scribed by Theodore Leber in to cause LCA. The genes include (1) reti- 18691 as a congenital form of nal guanylate cyclase (GUCY2D),17 (2) reti- retinitis pigmentosa. It rep- nal pigment epithelium–specific 65kD resents a clinically and genetically heter- protein (RPE65),18 (3) cone-rod ho- L 19-22 ogeneous disorder with severe visual meobox (CRX), (4) crumbs gene ho- impairment from birth.2,3 Fundus exami- molog of CRB1,23,24 (5) retinitis pigmen- nation results are not frequently initially tosa GTPase regulator–interacting protein normal, but chorioretinal atrophy, nar- (RPGRIP-1),25,26 and (6) AIPL1, encoding rowing of the retinal vasculature, intra- the aryl hydrocarbon receptor interact- retinal pigment migration, white fundus ing protein-like 1 protein.27,28 flecks, and macular aplasia have been de- The AIPL1 gene consists of 6 exons scribed.4-8 The retinal basis of the visual and encodes a protein of 384 amino acids. loss is shown by absent or severely dimin- This sequence includes 3 tetratricopep- ished rod and cone responses on electro- tide repeat motifs thought to be associ- retinography (ERG).9 Nystagmus, enoph- ated with protein-protein interaction, and thalmos, sluggish pupillary responses, its similarity with aryl hydrocarbon inter- keratoconus, cataracts, and hyperopia have acting protein is suggestive of a protein fold- also been described.10-12 ing function.27,28 The exact functions of the Leber congenital amaurosis is usu- AIPL1 gene are not fully understood. How- Author affiliations are listed at ally inherited as an autosomal recessive ever, recent data suggest that the protein the end of the article. trait, although dominant inheritance has may be involved in photoreceptor differ-

(REPRINTED) ARCH OPHTHALMOL / VOL 122, JULY 2004 WWW.ARCHOPHTHALMOL.COM 1029

©2004 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/27/2021 entiation during development and subsequent survival of NIGHT BLINDNESS, PHOTOATTRACTION, photoreceptors.29 Indeed, through interaction with the AND PHOTOAVERSION NUB1 protein, it might be involved in regulation of the cell-cycle progression during photoreceptor matura- Night blindness was reported in 13 probands and pho- tion.29 Mutations in AIPL1 account for 7% of LCA.28 toaversion in 4. Photoattraction (staring at lights) was Clinical outcomes differed for patients with LCA and noted in 2 probands (Table 1). GUCY2D mutations when compared with those with RPE65 defects30-33 in terms of the natural history of this VISUAL ACUITIES AND disorder. In addition, some heterozygous carriers of CYCLOPLEGIC REFRACTIONS GUCY2D mutations, who have offspring with LCA, have been shown to have significant cone abnormalities on ERG Visual acuities were found to vary between probands and results, with essentially normal rod ERG findings.34 Most ranged from 20/400 to light perception. Nine patients had heterozygotes with RPE65 mutations have normal ERG light perception. Seven patients had hand motion vision findings.32 (Table 1). Cycloplegic refractions performed in 10 pa- The purpose of this large study is to describe the phe- tients showed hyperopia in 8 (+3.00 diopters [D] to +7.00 notype of LCA in patients with AIPL1 mutations and com- D) and myopia in 2 (–0.50 D to –2.75 D). pare it with the known phenotypes of patients with mutations in other LCA genes. The phenotype of 26 patients RETINAL AND MACULAR APPEARANCE with LCA of different ethnic origins with mutations in AIPL1 is described. The genotype of most patients has Twenty-four probands with an AIPL1-related LCA geno- previously been published.15,28 The ERG and clinical find- type had some form of pigmentary retinopathy that ranged ings in a female heterozygous carrier are also reported. from mild midperipheral salt and pepper-like retinopathy to diffuse and severe chorioretinopathy (Figures 2, METHODS 3, 4, 5, 6 and 7). The youngest patient with pigmen- Informed consent was obtained from all patients involved in tary changes was 4 months old. Two patients, a 2-year- this study or from their legal guardians in accordance with the old and a 3-year-old, had essentially normal retinas with Declaration of Helsinki. The review and ethics boards of the indistinct foveal reflexes. A maculopathy of variable ap- institutions approved this study. pearance was noted in a significant number of patients (Figures 2, 3, 4, 5, and 7). Information about the macu- OPHTHALMIC EVALUATIONS lar appearance was available in 20 of the 26 probands. The clinical diagnosis of LCA was made on the basis of the fol- Maculopathy was noted in 16 (80%) of 20 probands. In lowing diagnostic criteria: severe visual impairment from birth 4 probands, all young children (ranging from ages 2-6 or during early infancy accompanied by nystagmus, absent or years), an abnormal indistinct foveal reflex was noted, very sluggish pupillary responses, and absent or markedly re- which likely represents an early stage of maculopathy. duced rod and cone ERGs. All ERGs were performed accord- This strongly suggests that a significant number of pa- ing to the International Society for Clinical Electrophysiology tients with LCA and AIPL1 mutations develop a macu- of Vision standards.35 The examinations were undertaken in 5 lopathy. The maculopathy ranged in appearance from mild centers and included slitlamp biomicroscopy, retinoscopy, and foveal atrophy with variable degrees of macular stip- indirect ophthalmoscopy following pupillary dilation (Table 1). pling to aplasia. The youngest patient with macular at- Clinical pictures were taken, and keratometry was performed. rophy was 8 years old (Table 1). GENETIC EVALUATIONS KERATOCONUS AND CATARACTS DNA was extracted from peripheral blood leukocytes or cheek swabs. A cohort of 303 patients with LCA was screened for mu- Information about the presence of keratoconus was avail- tations in AIPL1. Patients were from a wide range of racial and able in 19 probands (Table 1). Keratoconus was diag- ethnic backgrounds. The 6 exons of AIPL1 were screened us- nosed in 6 probands (32%), and cataracts were noted in ing single-strand conformation polymorphism analysis (SSCP) association with the keratoconus in 5 of these 6 pa- followed by direct sequencing when an aberrant migration pat- tients. Distinct hydrops with scarring and breaks in the tern was noted on the SSCP gels. In 39 probands, direct sequencing was used to screen for mutations in AIPL1, while in Descemet membrane were noted in proband 17. The cata- the others, SSCP was initially undertaken using primers and racts ranged from cortical changes to posterior subcap- conditions previously described.27 The genotype of most of the sular cataracts. Of interest, keratoconus and cataracts were patients with AIPL1-related LCA in this study has been pub- only seen in patients who were homozygous for AIPL1 lished previously (Figure 1).27,28 mutations. Keratoconus was not observed in patients with compound heterozygous mutations. The youngest pa- RESULTS tient with keratoconus and cataract was aged 10 years. Mutations in AIPL1 were detected in 26 probands with OPTIC DISC APPEARANCE LCA (Figure 1). Seventeen probands were homozygotes, while 9 were compound heterozygotes. Twenty- Varying degrees of optic nerve pallor were noted in all four of the 52 mutated AIPL1 alleles carried the W278X patients after the age of 6 years. The optic nerve head ap- mutation. All sequence changes identified in our pa- peared normal in children younger than 6 years, except tients were absent in 205 control samples. in an infant (Table 1).

(REPRINTED) ARCH OPHTHALMOL / VOL 122, JULY 2004 WWW.ARCHOPHTHALMOL.COM 1030

AIPL1 Mutations Optic Age at Visual Nerve Pigmentary Refraction, Proband Origin Allele 1 Allele 2 Examination History Acuity Maculopathy Pallor Keratoconus Cataract Retinopathy diopters 1 India M79T M79T 24 y Absence of LP Mild Moderate Absence Absence Severe NA NB and PA 2 Bangladesh W88X W88X 30 y NA LP Severe Moderate Moderate Mild Severe NA 3 Belgium V96I V96I 4 m NA No FF Mild Mild Absence Absence Absence NA 4 France Y134F Y134F NA Absence of NA NA NA NA NA Severe +5.00 NB Presence of PA 5 Palestine Q163X Q163X 10 y Presence of LP Mild Moderate Mild Moderate Severe NA NB 6 Morocco A197P A197P NA Absence of 5/200 NA NA NA NA Severe +7.00 NB Presence of PA 7 United C239R C239R 16 y Presence of HM Mild Moderate Absence Absence Severe −0.50 States NB 8 Saudi W278X W278X 8 y Presence of FF Moderate Mild Absence Absence Severe NA Arabia NB 9 United W278X W278X 57 y Presence of LP Moderate Moderate Mild Severe Severe NA States NB and DOP 10 United W278X W278X NA Presence of HM Moderate Mild Absence Absence Severe NA States NB 11 Pakistan W278X W278X 16 y Presence of LP Severe Moderate Moderate Absence Severe NA NB 12 Pakistan W278X W278X 25 y NA LP Severe Moderate Moderate Moderate Moderate NA 13 United W278X W278X 3 y Presence of HM IFR Absence Absence Absence Absence +7.00 States NB 14 Portugal W278X W278X NA Presence of LP NA NA NA NA Severe +7.00 NB and PA 15 Belgium W278X W278X NA NA NA NA NA NA NA Severe NA 16 Belgium W278X W278X NA NA LP Mild Mild NA NA Severe NA 17 India R302L R302L 16 y Absence of HM Moderate Moderate Severe Severe Moderate +6.00 NB and PA 18 United C42X G262S 17 y Presence of HM Mild Mild Absence Absence Severe NA States PAT 19 United V33 ins 8bp W278X 6 y Presence of HM IFR Absence Absence Absence Mild +6.00 States PAT 20 United T114I P376S 8 y Presence of 20/400 Severe Mild Absence Absence Moderate −2.75 States NB 21 France T114I P376S NA Absence of NA NA NA NA NA Severe NA NB Presence of PA 22 United Leu257 del W278X 2 y Presence of No FF IFR Absence Absence Absence Absence +6.50 States 9bp NB and DOP 23 United G262S W278X 19 y Presence of HM Mild Mild Absence Absence Moderate NA States NB 24 Ireland W278X IVS2-2AϾG 3 y Presence of FF IFR Absence Absence Absence Mild +3.00 NB 25 France W278X IVS2-2AϾG NA NA LP NA NA NA NA Severe NA 26 United W278X A336 del 2bp 27 y Presence of 20/1200 Mild Mild Absence Absence Severe NA States NB

Abbreviations: DOP, digito-ocular phenomenon; FF, fixation and following; HM, hand motions; IFR, indistinct foveal reflex; LP, light perception; NA, not available; NB, night blindness; PA, photoaversion; PAT, photoattraction.

ERG FINDINGS AIPL1 V96I Y134F A197P A336 del 2bp The ERG findings obtained in the 3 sets of clinically normal parents of probands 7, 10, and 26 who carry the AIPL1 W88X R302L mutation in a heterozygous state did not show any abnor- M79T T114I C239R malities. However, the ERG of 1 carrier parent of proband 2 with the W88X mutation showed significant rod 5′ 12 3 4 5 6 3′ abnormalities (Figure 8). She did not have any ocular complaints, and her clinical examination findings were nor- P376S mal. This 47-year-old mother had vision of 20/20 OU. Al- V33 ins 8bp Q163X though her retinal examination results were unremark- C42X L257 del 9bp W278X able, full-field flash ERG showed rod b-wave amplitudes to be reduced to approximately one third of normal, with IVS2-2A>G G262S no change in implicit time. This is well below the lower Figure 1. Structure of the AILPL1 gene with the relative locations of the limit of normal. The 30-Hz flicker and single flash cone mutations in the 26 probands.

(REPRINTED) ARCH OPHTHALMOL / VOL 122, JULY 2004 WWW.ARCHOPHTHALMOL.COM 1031

©2004 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/27/2021 Figure 2. W287X/W278X mutation, proband 12 at 25 years of age. Posterior Figure 5. W88X/W88X mutation, proband 2 at 30 years of age. Superior pole, right eye, showing atrophic macular area optic nerve pallor and midperiphery, left eye, showing intraretinal pigment accumulation, optic pigmentary changes. nerve pallor, and atrophic macula with pigmentary changes.

Figure 3. W287X/W278X mutation, proband 8 at 8 years of age. Left eye, Figure 6. T114I/P376S mutation, proband 20 at 8 years of age. Peripheral early macular changes showing retinal pigmentary epithelium disruption. retinal mottling.

Figure 4. W88X/W88X mutation, proband 2 at 30 years of age. Posterior Figure 7. T114I/P376S mutation, proband 20 at 8 years of age. Right eye, pole, left eye, showing atrophic macular and retinal pigment epithelium showing macular coloboma-like atrophy and mild optic nerve pallor. disruption and optic nerve pallor.

(REPRINTED) ARCH OPHTHALMOL / VOL 122, JULY 2004 WWW.ARCHOPHTHALMOL.COM 1032

µ 400 V µ 150 µV 150 V 300 µV 400 µV µ 100 µV 100 V 200 µV 200 µV 50 µV 100 µV 50 µV

0V 0V 0V 0V 0S 100 ms 0S 100 ms 0S 50 ms 0S 50 ms

µ 400 V µ 150 V 150 µV µ 300 µV 400 V µ 100 V 100 µV 200 µV 200 µV 50 µV 100 µV 50 µV

0V 0V 0V 0V

0S 100 ms 0S 100 ms 0S 50 ms 0S 50 ms

400 µV 150 µV 150 µV 400 µV 300 µV 100 µV 100 µV 200 µV 200 µV 50 µV 50 µV 100 µV 0V 0V 0V 0V

0S 100 ms 0S 100 ms 0S 50 ms 0S 50 ms

400 µV 150 µV 150 µV 300 µV 400 µV 100 µV 100 µV 200 µV 200 µV 50 µV 100 µV 50 µV

0V 0V 0V 0V 0S 100 ms 0S 100 ms 0S 50 ms 0S 50 ms

Figure 8. Top row, Electroretinogram (ERG), right eye, of the 47-year-old, heterozygous carrier parent of proband 2 carrying the W88X AIPL1 mutation. It shows a significantly reduced amplitude of rod-specific scotopic to one third of normal values and of maximal combined rod and cone response; cone-specific 30-Hz flicker and single flash cone ERGs are within normal limits. Second row, ERG of proband 2 at 27 years of age (carrying the W88X/W88X mutation) showing no measurable responses. Third row, ERG of proband 2’s 30-year-old affected sister (carrying the W88X/W88X mutation) showing no measurable responses. Fourth row, Typical normal findings in a 45-year-old control.

responses were within normal limits (Figure 8). The ERG pared with the reported GUCY2D phenotype,30,31,33 the responses were reproducible on repetition. AIPL1 phenotype appears to be similar in severity of visual loss. Phenotypical differences exist in the pattern of COMPARING THE LCA PHENOTYPES pigmentary changes, cataract, and keratoconus, which are more frequent in AIPL1-related LCA (Table 2). The LCA phenotypes with mutations in the other LCA genes The RPE65 phenotype reported in earlier studies30- (GUCY2D, RPE65, CRX, CRB1, and RPGRIP1) were com- 32,37,38 shows that the visual acuities, visual fields, and ERG pared with the LCA phenotypes of the current study and measurements were better than in the AIPL1 phenotype. tabulated in Tables 2, 3, 4, 5, and 6. The AIPL1-related Patients with RPE65-related LCA may develop a mild macu- LCA phenotype is severe in nature, with pronounced maculopathy, and the documented peripheral retinal changes lar involvement in individuals older than 6 years with vary- are characterized as grainy and/or salt and pepper-like. The ing degrees of optic nerve pallor. Additional findings of kera- maculopathy of patients with AIPL1-related LCA appears toconus and cataract could be present. to be more pronounced in all probands older than 6 years, Both GUCY2D-related and AIPL1-related LCA phe- while the peripheral retinal changes range from mottling notypes have markedly decreased visual acuities, visual to bone spicule-like formation. Cataract and keratocu- fields, and ERGs.30,31,33 However, maculopathy, remark- nus were present in one third of the patients with AIPL1- able peripheral pigmentary changes, cataract, and sig- related LCA. Lorenz et al32 conclude that patients with LCA nificant optic disc pallor were not detected in patients and RPE65 mutations are distinguishable on clinical with mutations in GUCY2D.30,31,33 Keratoconus was re- grounds, based on their measurable visual acuities, their ported by El-Shanti et al36 in a Jordanian pedigree. Com- transient visual improvement in childhood followed by de-

(REPRINTED) ARCH OPHTHALMOL / VOL 122, JULY 2004 WWW.ARCHOPHTHALMOL.COM 1033

©2004 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/27/2021 Table 2. Comparisons of Leber Congenital Amaurosis Phenotypes: Patients With GUCY2D Mutations vs Patients With AIPL1 Mutations

Optic Sample Acuity, Refraction, Pigmentary Nerve Source Size Gene Range diopters Visual Field Electroretinogram Maculopathy Retinopathy Keratoconus Cataract Pallor Perrault 20 GUCY2D Counting Severe Nondetectable Nondetectable Absent Normal at 1 patient Absent et al30 fingers hyperopia birth, salt to light and perception pepper-like changes later Dharmaraj 6 GUCY2D 20/150 to 6 patients Nondetectable Nondetectable Absent Essentially Absent Absent et al31 light (+1.00 to normal perception +5.50) retina in some; mild pigmentary changes in others Lotery 2 GUCY2D 20/1333 to 2 patients Absent Absent Absent et al33 no light (+1.50 to perception +4.00) Current 26 AIPL1 20/400 to 8 patients Nondetectable Nondetectable Pronounced Marked bone Present in Present in Present study light (+3.00 to in 80% spicule-like 6of18 5of18 after 6 perception +7.00); pigmentary patients patients years 2 patients changes in of age (−0.50 to 84% −2.00)

Table 3. Comparisons of Leber Congenital Amaurosis Phenotypes: Patients With RPE65 Mutations vs Patients With AIPL1 Mutations

Optic Sample Acuity, Refraction, Pigmentary Nerve Source Size Gene Range diopters Visual Field Electroretinogram Maculopathy Retinopathy Keratoconus Cataract Pallor Lorenz 4 RPE65 20/70 to 4 patients with Preserved Rod, Mild Granular Absent Absent et al32 20/200 hyperopia peripheral nondetectable; cone, recordable progressed to nondetectable Thompson 20 RPE65 20/60 to hand 7 patients with Residual Residual to et al37 motions; hyperopia; nondetectable most 3 patients patients with 20/100 myopia; 13 patients not reported Lotery 12 RPE65 20/50 to light 9 patients et al33 perception; (+0.50 to most +3.50); patients 3 patients 20/200 (−0.50 to −1.50) Current 26 AIPL1 20/400 to 8 patients Nondetectable Nondetectable Pronounced Marked bone Present in Present in Present study light (+3.00 to in 80% spicule-like 6of18 5of18 after 6 perception; +7.00); pigmentary patients patients years most 2 patients changes in patients (−0.50 to 84% hand −2.00) motions

terioration in later life, measurable cone ERGs (which also Compared with that of patients with CRB1 muta- diminish in later life), measurable visual fields, and sig- tions, the phenotype of our patients with AIPL1 muta- nificant night blindness. The data from our study suggest tions appears to be less variable and more severe. Small that patients with LCA and mutations in AIPL1 do not have white dots and zonal retinal/choroidal hypoplasia were a similar course (Table 3). seen in the patients with CRB1-related LCA23 but not in From the several reported cases of patients with patients with AIPL1-related LCA (Table 5). The pres- LCA and CRX mutations, visual acuities of 20/300 ence of cataract, keratoconus, and optic disc pallor were to light perception, with 1 case of 20/80, were not reported in the CRB1-related LCA phenotype. The described.15,16,19-22,31,33,39-43 Marked atrophy in the macula constant features reported in the CRB1-related pheno- was recorded in 71% of CRX-related LCA, while in AIPL1- type were moderate to high hyperopia, the relatively early related LCA, maculopathy was pronounced in 80% of the appearance of white spots, and nummular pigment clumps patients after 6 years of age. Marked pigmentary reti- in the retina.23 nopathy was noticed in 84% of patients with AIPL1- The RPGRIP1-related LCA phenotype has been re- related LCA unlike in CRX-related LCA, where it was ob- ported in 3 patients.25 Visual acuity was light percep- served in 33% (Table 4). tion. Hyperopia and absence of intraretinal pigment mi-

(REPRINTED) ARCH OPHTHALMOL / VOL 122, JULY 2004 WWW.ARCHOPHTHALMOL.COM 1034

©2004 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/27/2021 Table 4. Comparisons of Leber Congenital Amaurosis Phenotypes: Patients With CRX Mutations vs Patients With AIPL1 Mutations

Optic Sample Acuity, Refraction, Pigmentary Nerve Source Size Gene Range diopters Visual Field Electroretinogram Maculopathy Retinopathy Keratoconus Cataract Pallor Jacobson et al,21 143 CRX 20/300 to −7.00 to +6.00 Restriction Decreased to Present in 8 Present in Absent Present in Lotery et al,33 light (Ͻ30 degrees) nondetectable; of 14 1 patient 6of14 Nakamura et al,42 perception; nonrecordable 95% decrease in patients patients Rivolta et al,41 20/80 in 1 cone amplitude Silva et al,22 patient Sohocki et al,15 Swaroop et al,43 Zhang et al40 Current study 26 AIPL1 20/400 to 8 patients Nondetectable Nondetectable Pronounced Marked bone Present in Present in Present light (+3.00 to in 80% spicule-like 6of18 5of18 after 6 perception +7.00); pigmentary patients patients years of 2 patients changes in age (−0.50 to 84% −2.00)

Table 5. Comparisons of Leber Congenital Amaurosis Phenotypes: Patients With CRB1 Mutations vs Patients With AIPL1 Mutations*

Optic Sample Acuity, Refraction, Pigmentary Nerve Source Size Gene Range diopters Visual Field Electroretinogram Maculopathy Retinopathy Keratoconus Cataract Pallor Lotery 19 CRB1 20/40 to light 12 patients Decreased to Present in Present in Present Absent et al23 perception (+0.80 to nondetectable some some +5.50) Current 26 AIPL1 20/400 to 8 patients Nonrecordable Nondetectable Pronounced Marked bone Present in Present in Present study light (+3.00 to in 80% spicule-like 6of18 5of18 after perception +7.00); pigmentary patients patients 6 years 2 patients changes in of age (−0.50 to 84% −2.00)

Abbreviation: RPE, retinal pigment epithelium. *Nummular pigmentation in the retina and retinal zonal atrophy with hypoplasia of the choriocapillaris and RPE were present in some patients in the Loteryetal study but absent in the current study. Small retinal dots were present in many of the patients in the Lotery et al study but absent in the current study.

Table 6. Comparisons of Leber Congenital Amaurosis Phenotypes: Patients With RPGRIP1 Mutations vs Patients With AIPL1 Mutations

Optic Sample Acuity, Refraction, Pigmentary Nerve Source Size Gene Range diopters Visual Field Electroretinogram Maculopathy Retinopathy Keratoconus Cataract Pallor Dryja 3 RPGRIP1 Light +2.60 to +6.90 Nonrecordable Nondetectable Absent in 1 of Reported in Absent Absent Present et al25 perception 1 patients 1 proband (bone-spicule like) Current 26 AIPL1 20/400 to 8 patients Nondetectable Nondetectable Pronounced Marked bone Present in Present in Present study light (+3.00 to in 80% spicule-like 6of18 5of18 after 6 perception +7.00); pigmentary patients patients years 2 patients changes in of age (−0.50 to 84% −2.00)

gration were noted in 2 patients. However, bone spicule- ing in bone spicule-like pigment and gross pigment clumps like pigmentary deposits in the midperipheral zone were in the retinas were observed. Overall, a high prevalence noted in a third patient. No evidence of maculopathy as of macular lesions was observed in our patients com- seen in the patients with AIPL1-related LCA was ob- pared with patients with LCA caused by mutations in the served (Table 6). other 5 genes implicated in this disease. Atrophic macular lesions were particularly frequent and were observed COMMENT in 16 (80%) of 20 patients; 11 harbored a premature stop- codon mutation, either in a homozygous or a heterozy- The retinal phenotype of AIPL1-related LCA is that of a gous state. Macular involvement as seen on ophthalmos- severe, congenital retinal dystrophy with a notable macu- copy likely begins with an indistinct dull or irregular foveal lopathy. The retinal appearances in our patients ranged reflex and progresses to a diffuse ill-defined area of reti- from near normal (in a 3-year-old and a 6-year-old) to se- nal pigment stippling and atrophy, leading to a marked verely atrophic (and in all patients older than 6 years) with atrophic maculopathy. Owing to the differences in age at marked maculopathy and pigmentary retinopathy. Vary- the time of first examination, it was not possible to deter- ing degrees of intraretinal pigment migration culminat- mine the accurate age of onset of the maculopathy.

(REPRINTED) ARCH OPHTHALMOL / VOL 122, JULY 2004 WWW.ARCHOPHTHALMOL.COM 1035

©2004 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/27/2021 The heterozygous carrier parent of the W88X standing of the pathogenesis of each molecular subtype mutation was found to have a significant and reproduc- of LCA will provide further insight into treatment. ible rod ERG abnormality with essentially normal cone ERG results. These ERG findings are significantly dif- Submitted for publication October 10, 2002; final revision ferent from the heterozygous carriers of GUCY2D muta- received April 3, 2003; accepted June 6, 2003. tions, who have significant cone ERG abnormalities but From the Johns Hopkins Center for Hereditary Eye Dis- relatively normal rod ERG findings.34 The rod ERG eases, Baltimore, Md (Drs Dharmaraj, De Pool, and abnormalities in the AIPL1 carrier correlate with recent Maumenee); the Departments of Molecular Genetics (Drs reports showing AIPL1 expression exclusively in rod Leroy, Payne, and Bhattacharya) and Clinical Ophthal- photoreceptors in the differentiated retina.44 However, mology (Drs Bird and Leroy), Institute of Ophthalmology, more ERGs in carriers of AIPL1 mutations need to be University College of London, London, England; the De- studied to better understand the role of AIPL1 in rela- partment of Ophthalmology and Center for Medical Genet- tion to rod function. ics, Ghent University Hospital, Ghent, Belgium (Dr Leroy); The presence of keratoconus in patients with LCA the Departments of Ophthalmology and Pathology, Colum- has been well documented.45-48 The high incidence of kera- bia University, New York, NY (Dr Sohocki); McGill Ocular toconus in patients with a homozygous sequence change Genetics Lab, Montreal Children’s Hospital, Montreal, Que- of AIPL1 in our cohort may well be significant. Kerato- bec (Dr Koenekoop); Unite´ de Recherches sur les Handicaps conus was observed in 6 probands, all with homozy- Geńe´tiques de l’Enfant, Inserm U393, Hoˆpital des Enfants gous mutations. There is no definitive consensus about Malades, Paris, France (Drs Perrault and Kaplan); the Bio- the origin of keratoconus in patients with LCA. The in- medical and Genetic Engineering Division, Dr AQ Khan Re- cidence of keratoconus has been reported to be as high search Laboratories, Islamabad, Pakistan (Drs Anwar, Khaliq, as 54.5 cases per 100.0 in the general population, and it and Ismail); Stanley Medical College, University of Madras, has been noted in 29% of children with LCA and 2% of Madras, India (Dr Devi); The Retinal Foundation of the South- all children with blindness.10,49 Keratoconus in patients west Dallas, Tex (Dr Birch); Instituto de Glaucoma y Ge- with LCA occurred in 2% of 0- to 14-year-olds and in netic a Ocular, Rio Piedras, Puerto Rico (Dr Izquierdo); Cen- 30% of 15- to 45-year-olds, further illustrating the later tre de Geńe´tique Humaine Institut de Pathologie et de Geńe´tique, onset of the pathologic corneal features in comparison Loverval, Belgium (Dr Van Maldergem); the Department of with the retinal dysplasia.50 The absence of keratoconus Biological Sciences, Brunel University, London (Dr Payne); prior to 9 years of age also has been well documented46 the Electrophysiology Department, Moorfields Eye Hospital, and is the case in our cohort too. London (Dr Holder). The authors have no relevant financial Cataract has been associated with many different interest in this article. types of retinal dystrophy. Its association with retinitis This research was supported by grants from the Foun- pigmentosa has been well documented.51,52 Cataract has dation for Retinal Research, Highland Park, Ill; the Edel & been noted at or beyond the second decade of life in pa- Krieble Funds of the Johns Hopkins Center for Hereditary Eye tients with LCA.46 In this study, cataracts were observed Diseases, Baltimore, Md; the Grousbeck Family Foundation, in 5 probands (27%). Progressive retinal degenerative Stanford, Calif; the Fonds voor Research in Oftalmologie/ changes in association with keratoconus and cataract have Fonds de la Recherche en Ophtalmologie, Edegem, Antwerp, been reported during the course of the disorder.46,47 The Belgium (Dr Leroy); the Bijzonder Onderzoeksfonds of incidence of both keratoconus and cataract increased with Ghent University, Ghent, Belgium (Dr Leroy); the Founda- increasing age in our cohort. tion Fighting Blindness-Canada, Toronto, Ontario (Dr Koenen- The LCA phenotypes are highly variable15,23,31,32 and koop); the Canadian Institutes of Health Research, Ottawa, change with age,46 and the phenotypes associated with Ontario (Dr Koenenkoop); Fonds de la recherche en Sante´du the currently known LCA genes overlap.31-33 Compari- Que´beć, Montreál, Que´beć (Dr Koenenkoop); the Kirchgess- sons between the reported LCA phenotypes of different ner Foundation, Los Angeles, Calif (Dr Sohocki); the Knights studies23,25,30-33 are hampered by a lack of uniform assess- Templar Eye Foundation, Chicago, Ill (Dr Sohocki); the Foun- ment strategies, age matching, and uniform follow-up. dation Fighting Blindness, Owings Mills, Md (Dr Sohocki); Despite these obvious difficulties, it is important to study Fight for Sight, New York (Dr Sohocki); the Research Divi- these LCA phenotypes in an effort to understand the evo- sion of Prevent Blindness America, Schaumburg, Ill (Dr So- lution of disease based on genotype. hocki); and William R. Acquavella (Dr Sohocki). In summary, patients with AIPL1-related LCA ap- Dr Sohocki is the William R. Acquavella Scholar of Oph- pear to have a particularly severe phenotype, character- thalmic Research, Columbia University, New York. ized by marked visual impairment, nondetectable fields These authors contributed equally to the study: Sha- and ERGs, optic disc pallor, maculopathy, peripheral reti- rola Dharmaraj, MD, FRCS, and Bart P. Leroy, MD. nal bone spicule-like pigmentation, and a significant We thank the families for support and cooperation. We prevalence of keratoconus and cataract. also thank the photography departments of all the insti- Mutations in AIPL1 disrupt the normal function of tutes for their professional assistance and to Olof Sundin, photoreceptors. AIPL1 is not only expressed in mature PhD, for reviewing the manuscript. rod photoreceptors44 but also during development in both Correspondence: Sharola Dharmaraj, MD, FRCS, The rods and cones.29 The dysfunctional role of AIPL1 in pho- Johns Hopkins Center for Hereditary Eye Diseases, Maumenee toreceptor cell cycle progression leads to photoreceptor 517, Wilmer Eye Institute, Johns Hopkins Medical In- cell death during development by disrupting the nor- stitutions, 600 N Wolfe St, Baltimore, MD 21287-9237 mal regulation of the cell cycle.29 More detailed under- ([email protected]).

(REPRINTED) ARCH OPHTHALMOL / VOL 122, JULY 2004 WWW.ARCHOPHTHALMOL.COM 1036

©2004 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/27/2021 pineal gene on 17p cause Leber congenital amaurosis. Nat Genet. 2000;24:79-83. REFERENCES 28. Sohocki MM, Perrault I, Leroy BP, et al. Prevalence of AIPL1 mutations in inherited retinal degenerative disease. Mol Genet Metab. 2000;70:142-150. 1. Leber T. Uber Retinitis pigmentosa und Angeborene Amaurose. Graefes Arch Klin 29. Akey DT, Zhu X, Dyer M, et al. The inherited blindness associated protein AIPL1 Exp Ophthalmol. 1869;15:13-20. interacts with the cell cycle regulator protein NUB1. Hum Mol Genet. 2002;11: 2. Camuzat A, Rozet JM, Dollfus H, et al. Evidence of genetic heterogeneity of Leb- 2723-2733. er’s congenital amaurosis (LCA) and mapping of LCA1 to chromosome 17p13. 30. Perrault I, Rozet JM, Ghazi I, et al. Different functional outcome of RetGC1 and Hum Genet. 1996;97:798-801. RPE65 gene mutations in Leber congenital amaurosis. Am J Hum Genet. 1999; 3. Waardenburg PJ. Congenital and early infantile retinal dysfunction (high- 64:1225-1228. graded) amblyopia and amaurosis of Leber. In: Waardenburg PJ, Franceschetti 31. Dharmaraj SR, Silva ER, Pina AL, et al. Mutational analysis and clinical correla- A, Klein D, eds. Genetics and Ophthalmology. Oxford, England: Blackwell Sci- tion in Leber congenital amaurosis. Ophthalmic Genet. 2000;21:135-150. entific; 1961:1567-1581. 32. Lorenz B, Gyurus P, Preising M, et al. Early-onset severe rod-cone dystrophy in 4. Heckenlively JR, Foxman SG, Parelhoff ES. Retinal dystrophy and macular colo- young children with RPE65 mutations. Invest Ophthalmol Vis Sci. 2000;41:2735- boma. Doc Ophthalmol. 1988;68:257-271. 2742. 5. Mizuno K, Takei Y, Sears ML, et al. Leber’s congenital amaurosis. Am J Oph- 33. Lotery AJ, Namperumalsamy P, Jacobson SG, et al. Mutation analysis of 3 genes thalmol. 1977;83:32-42. in patients with Leber congenital amaurosis. Arch Ophthalmol. 2000;118:538-543. 6. Noble KG, Carr RE. Leber’s congenital amaurosis: a retrospective study of 33 cases 34. Koenekoop RK, Fishman GA, Iannaccone A, et al. Electroretinographic abnor- and a histopathological study of one case. Arch Ophthalmol. 1978;96:818-821. malities in parents of patients with Leber congenital amaurosis who have het- 7. Margolis S, Scher BM, Carr RE. Macular colobomas in Leber’s congenital am- erozygous GUCY2D mutations. Arch Ophthalmol. 2002;120:1325-1330. aurosis. Am J Ophthalmol. 1977;83:27-31. 35. Marmor MF, Zrenner E. Standard for clinical electroretinography (1999 update): 8. Franc¸ois J. Leber’s congenital tapeto-retinal degeneration. Int Ophthalmol Clin. International Society for Clinical Electrophysiology of Vision. Doc Ophthalmol. 1968;8:929-947. 1998-1999;97:143-156. 9. Franceschetti A, Dieterle P. L’importance diagnostique de l’electrore´tinogramme 36. El-Shanti H, Al-Salem M, El-Najjar M, et al. A nonsense mutation in the retinal dans les de´ge´ne´rescences tape´tore´tiniennes avec re´trecissement du champ vi- specific guanylate cyclase gene is the cause of Leber congenital amaurosis in a suel et he´me´ralopie. Confin Neurol. 1954;14:184-186. large inbred kindred from Jordan [letter]. J Med Genet. 1999;36:862-865. 10. Elder MJ. Leber congenital amaurosis and its association with keratoconus and 37. Thompson DA, Gyurus P, Fleischer LL, et al. Genetics and phenotypes of RPE65 keratoglobus. J Pediatr Ophthalmol Strabismus. 1994;31:38-40. mutations in inherited retinal degeneration. Invest Ophthalmol Vis Sci. 2000;41: 11. Wagner RS, Caputo AR, Nelson LB, Zanoni D. High hyperopia in Leber’s con- 4293-4299. genital amaurosis. Arch Ophthalmol. 1985;103:1507-1509. 38. Hamel CP, Griffoin JM, Lasquellec L, Bazalgette C, Arnaud B. Retinal dystro- 12. Stoiber J, Muss WH, Ruckhofer J, et al. Recurrent keratoconus in a patient with phies caused by mutations in RPE65: assessment of visual functions. Br J Oph- Leber congenital amaurosis. Cornea. 2000;19:395-398. thalmol. 2001;85:424-427. 13. Heckenlively JR. Autosomal dominant retinitis pigmentosa. In: Heckenlively JR, ed. 39. Koenekoop RK, Loyer M, Dembinska O, Beneish R. Visual improvement in Leber Retinitis Pigmentosa. Philadelphia, Pa: JB Lippincott Co; 1988:125-149. congenital amaurosis and the CRX genotype. Ophthalmic Genet. 2002;23:49-59. 14. Sorsby A, Williams CE. Retinal aplasia as a clinical entity.BMJ. 1960;1:293- 40. Zhang Q, Li S, Guo X, et al. Screening for CRX gene mutations in Chinese pa- 297. tients with Leber congenital amaurosis and mutational phenotype. Ophthalmic 15. Sohocki MM, Sullivan LS, Mintz-Hittner HA, et al. A range of clinical phenotypes Genet. 2001;22:89-96. associated with mutations in CRX, a photoreceptor transcription-factor gene. Am 41. Rivolta C, Peck NE, Fulton AB, Fishman GA, Berson EL, Dryja TP. Novel frame- J Hum Genet. 1998;63:1307-1315. shift mutations in CRX associated with Leber congenital amaurosis. Hum Mu- 16. Rivolta C, Berson EL, Dryja TP. Dominant Leber congenital amaurosis, cone-rod degeneration, and retinitis pigmentosa caused by mutant versions of the tran- tat. 2001;18:550-551. scription factor CRX. Hum Mutat. 2001;18:488-498. 42. Nakamura M, Ito S, Miyake Y. Novel de novo mutation in CRX gene in a Japanese 17. Perrault I, Rozet JM, Calvas P, et al. Retinal-specific guanylate cyclase gene mu- patient with Leber congenital amaurosis. Am J Ophthalmol. 2002;134:465-467. tations in Leber’s congenital amaurosis. Nat Genet. 1996;14:461-464. 43. Swaroop A, Wang QL, Wu W, et al. Leber congenital amaurosis caused by a ho- 18. Marlhens F, Bareil C, Griffoin JM, et al. Mutations in RPE65 cause Leber’s con- mozygous mutation (R90W) in the homeodomain of the retinal transcription fac- genital amaurosis. Nat Genet. 1997;17:139-141. tor CRX: direct evidence for the involvement of CRX in the development of pho- 19. Tzekov RT, Liu Y, Sohocki MM, et al. Autosomal dominant retinal degeneration toreceptor function. Hum Mol Genet. 1999;8:299-305. and bone loss in patients with a 12-bp deletion in the CRX gene. Invest Ophthal- 44. van Der Spuy J, Chapple JP, Clark BJ, et al. The Leber congenital amaurosis gene mol Vis Sci. 2001;42:1319-1327. product AIPL1 is localized exclusively in rod photoreceptors of the adult human 20. Freund CL, Wang QL, Chen S, et al. De novo mutations in the CRX homeobox retina. Hum Mol Genet. 2002;11:823-831. gene associated with Leber congenital amaurosis. Nat Genet. 1998;18:311-312. 45. Flanders M, Lapointe ML, Brownstein S, Little JM. Keratoconus and Leber’s con- 21. Jacobson SG, Cideciyan AV, Huang Y, et al. Retinal degenerations with trunca- genital amaurosis: a clinicopathological correlation. Can J Ophthalmol. 1984; tion mutations in the cone-rod homeobox (CRX) gene. Invest Ophthalmol Vis 19:310-314. Sci. 1998;39:2417-2426. 46. Heher KL, Traboulsi EI, Maumenee IH. The natural history of Leber’s congenital am- 22. Silva E, Yang JM, Li Y, et al. A CRX null mutation is associated with both Leber aurosis: age-related findings in 35 patients. Ophthalmology. 1992;99:241-245. congenital amaurosis and a normal ocular phenotype. Invest Ophthalmol Vis Sci. 47. Schroeder R, Mets MB, Maumenee IH. Leber’s congenital amaurosis: retrospec- 2000;41:2076-1079. tive review of 43 cases and a new fundus finding in two cases. Arch Ophthalmol. 23. Lotery AJ, Jacobson SG, Fishman GA, et al. Mutations in the CRB1 gene cause 1987;105:356-359. Leber congenital amaurosis. Arch Ophthalmol. 2001;119:415-420. 48. Leighton DA, Harris R. Retinal aplasia in association with macular coloboma, kera- 24. den Hollander AI, Heckenlively JR, van den Born LI, et al. Leber congenital am- toconus and cataract. Clin Genet. 1973;4:270-274. aurosis and retinitis pigmentosa with Coats-like exudative vasculopathy are as- 49. Kennedy RH, Bourne WM, Dyer JA. A 48-year clinical and epidemiologic study sociated with mutations in the crumbs homologue 1 (CRB1) gene. Am J Hum of keratoconus. Am J Ophthalmol. 1986;101:267-273. Genet. 2001;69:198-203. 50. Alstro¨m CH, Olson O. Heredo-retinopathia congenitalis monohybrida recessiva 25. Dryja TP, Adams SM, Grimsby JL, et al. Null RPGRIP1 alleles in patients with autosomalis. Hereditas. 1957;43:1-178. Leber congenital amaurosis. Am J Hum Genet. 2001;68:1295-1298. 51. Auffarth GU, Tetz MR, Krastel H, Blankenagel A, Volcker HE. Complicated cata- 26. Gerber S, Perrault I, Hanein S, et al. Complete exon-intron structure of the RPGR- racts in various forms of retinitis pigmentosa: type and incidence [in German]. interacting protein (RPGRIP1) gene allows the identification of mutations un- Ophthalmologe. 1997;94:642-646. derlying Leber congenital amaurosis. Eur J Hum Genet. 2001;9:561-571. 52. Fishman GA, Anderson RJ, Lourenco P. Prevalence of posterior subcapsular lens 27. Sohocki MM, Bowne SJ, Sullivan LS, et al. Mutations in a new photoreceptor- opacities in patients with retinitis pigmentosa. Br J Ophthalmol. 1985;69:263-266.

(REPRINTED) ARCH OPHTHALMOL / VOL 122, JULY 2004 WWW.ARCHOPHTHALMOL.COM 1037