Homozygous Deletion in CDH3 and Hypotrichosis with Juvenile Macular Dystrophy

7. Shanks ME, Downes SM, Copley RR, et al. Next-generation sequencing (NGS) Report of a Case. A 48-year-old man had a 21-year his- as a diagnostic tool for retinal degeneration reveals a much higher detection rate in early-onset disease [published online September 12, 2012]. Eur J Hum tory of deterioration of central vision. The original di- Genet. doi:10.1038/ejhg.2012.172. agnosis was Stargardt disease. Initial symptoms at age 17 years included photosensitivity, abnormal color vision, and central scotomata. His sister has the same phenotype and the parents were likely to be related. The pro- Homozygous Deletion in CDH3 and band and his sister both gave a history of having very fine, Hypotrichosis With Juvenile Macular sparse hair that never thickened, with a persistently vis- Dystrophy ible scalp (Figure 1A). Funduscopy in the proband re- vealed bilateral symmetrical macular degeneration with ypotrichosis associated with juvenile macular dys- sparing of the peripheral retina (Figure 1B and C). Vi- trophy (HJMD; OMIM 601553) is a rare autoso- sual acuities were 6/760 OD and 6/96 OS. Goldmann vi- H mal recessive disorder characterized by short scalp sual field testing showed bilateral central scotomata hair from birth and progressive macular degeneration. Loss (Figure 1D). Electrophysiology showed extinguished pat- of central vision usually occurs between the second and tern electroretinograms, normal scotopic responses, and fourth decades of life. Mutations in the P-cadherin gene significant reduction in amplitudes of both a and b waves (CDH3; GenBank NM_001793) were first reported to un- in the standard flash electroretinogram and photopic re- derlie HJMD by Sprecher et al1; splice, missense, and non- sponses. The electro-oculogram light rise was normal in sense mutations have since been described.2-5 both eyes.

A B

C D 120 105 90 75 60 135 70 45 60

150 50 30 40 30 165 15 20 10 18090 80 70 60 50 40 30 20 10 10 20 30 40 50 60 70 80 90 0

10 20 195 345 30 40 210 50 330 60

225 70 315 240255 270 285 300

Figure 1. Clinical spectrum of the patient with hypotrichosis associated with juvenile macular dystrophy. A, Sparse hair in the proband at age 48 years. B, Color fundus photograph showing macular degeneration. C, Color fundus photograph of the same eye showing degeneration confined to the macular and peripapillary regions, sparing the mid and peripheral retina. D, Left visual field showing extensive central scotoma (the findings are similar in the right eye).

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Exon, bp 45 115 86 144 156 145 176 129 186 242 146 225 207 131 147 210

Intron, bp 211 30 631 1663 223 105 829 993 1205 2054 380 2161 3982 3327 391 2269

Intron 11 Intron 13 B

C 1 2345678

TTT GGGAGGCCAAGGCAG TT GGAT CACTT GAGGGT G

Breakpoint

D Exon 14 1018 bp Exon 11

729 bp

506 bp 396 bp 344 bp 298 bp 297 bp

GGT CTT GGCCAT GGACAA TGT CCT CCT GCT GGT GCT GC

E Extracellular Plasma membrane Intracellular

Wild type N-terminus EC1 EC2 EC3 EC4 EC5 C-terminus 829 amino acids β-catenin

Mutant N-terminus EC1 EC2 EC3 C-terminus 685 amino acids β-catenin

Figure 2. Mutation screening. A, Schematic diagram of the genomic structure of CDH3. Boxes indicate exons; lines, introns; and bp, base pairs. All are to scale except for regions of intronic DNA larger than 1 kilobase, which are represented as slashed lines. Exon and intron sizes are marked, as are the start and stop codons. The exons encoding the calcium-binding domains are shaded blue. B, Sequence of the deletion break point showing intron 11 spliced directly to intron 13 (not present in the Database of Genomic Variants). C, Expression of CDH3 in lymphocytes from the patient and a control by reverse transcription–polymerase chain reaction amplification of RNA using gene-specific primers spanning the junctions of exons 10 and 11 (forward) and 14 and 15 (reverse); human retinal complementary DNA was used as a control. The wild-type fragment should be 729 bp; the fragment amplified from the patient is 297 bp, lacking the 432 bp from exons 12 and 13. Lane 1 is the marker; 2, patient with reverse transcriptase; 3, patient without reverse transcriptase; 4, control with reverse transcriptase; 5, control without reverse transcriptase; 6, human retinal complementary DNA; 7, human genomic DNA; and 8, no-template control. D, Confirmation by sequence analysis. E, The domain structure of P-cadherin is represented diagrammatically. The protein consists of 5 extracellular calcium-binding domains (EC1-EC5), a transmembrane region, and a short intracellular tail that binds to ␤-catenin. The predicted mutant protein missing EC4, EC5, and part of the transmembrane domain is shown below.

The phenotype prompted us to undertake mutation by sequencing. Failure to amplify exons 12 and 13 in screening of CDH3, which comprises 16 exons span- the patient, compared with a control, led us to specu- ning approximately 55 kilobases of genomic DNA late that there could be a small intragenic deletion. (Figure 2A). Exons 1 through 11 and 14 through 16 Primers located in introns 11 and 14 amplified a were successfully amplified using primers as described 1607–base pair (bp) fragment from the patient, the by Kjaer et al.6 No nucleotide changes were detected expected size being 10 422 bp. Sequencing confirmed

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©2012 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/28/2021 a homozygous deletion of 8815 bp in both siblings Funding/Support: This work was supported by the Ox- with break points in introns 11 and 13 resulting in ford Partnership Comprehensive Biomedical Research loss of exons 12 and 13 (Figure 2A and B). Further Centre funded by the Department of Health NIHR Bio- examination of the region showed a 34-bp repeat (dif- medical Research Centre Programme and by Oxford Rad- fering by only 1 bp) flanking the break points, sug- cliffe Hospital Flexibility and Sustainability Funding. gesting homologous recombination as the mechanism Disclaimer: The views expressed in this article are those for generating this deletion. The predicted result of of the authors and not necessarily those of the Depart- this deletion would be that exon 11 splices directly to ment of Health. exon 14 and remains in frame, resulting in a protein of 1. Sprecher E, Bergman R, Richard G, et al. Hypotrichosis with juvenile macu- 685 amino acids, compared with the wild-type protein lar dystrophy is caused by a mutation in CDH3, encoding P-cadherin. Nat Genet. of 829 amino acids (Figure 2E). This was confirmed 2001;29(2):134-136. using complementary DNA from patient and control 2. Indelman M, Eason J, Hummel M, et al. Novel CDH3 mutations in hypotrichosis with juvenile macular dystrophy. Clin Exp Dermatol. 2007;32(2):191-196. lymphocytes and sequencing the products (Figure 2C 3. Shimomura Y, Wajid M, Kurban M, Christiano AM. Splice site mutations in and D). the P-cadherin gene underlie hypotrichosis with juvenile macular dystrophy. Dermatology. 2010;220(3):208-212. 4. Kamran-ul-Hassan Naqvi S, Azeem Z, Ali G, Ahmad W. A novel splice- Comment. Hypotrichosis associated with juvenile acceptor site mutation in CDH3 gene in a consanguineous family exhibiting macular dystrophy is caused by mutations in CDH3, hypotrichosis with juvenile macular dystrophy. Arch Dermatol Res. 2010; 302(9):701-703. which encodes P-cadherin, a member of the classic 5. Jelani M, Salman Chishti M, Ahmad W. A novel splice-site mutation in the cadherin family. We report here, to our knowledge for CDH3 gene in hypotrichosis with juvenile macular dystrophy. Clin Exp Dermatol. the first time, an intragenic deletion causing HJMD 2009;34(1):68-73. 6. Kjaer KW, Hansen L, Schwabe GC, et al. Distinct CDH3 mutations cause ec- that results in the homozygous loss of exons 12 and todermal dysplasia, ectrodactyly, macular dystrophy (EEM syndrome). JMed 13 of CDH3. The resultant transcript has exon 11 Genet. 2005;42(4):292-298. 7. Leibu R, Jermans A, Hatim G, Miller B, Sprecher E, Perlman I. Hypotrichosis spliced directly to exon 14, and although it remains in with juvenile macular dystrophy: clinical and electrophysiological assess- frame, the predicted protein loses extracellular ment of visual function. Ophthalmology. 2006;113(5):841-847, e3. calcium-binding domains 4 and 5 and part of the transmembrane domain and would therefore be nonfunctional. Kjaer et al6 have shown that mutations in CDH3 Bilateral Ophthalmic Artery Occlusions also cause ectodermal dysplasia, ectrodactyly, and Due to Probable Varicella-Zoster macular dystrophy (EEM; OMIM 225280); they also Virus Vasculopathy discuss possible mechanisms for this phenotypic varia- tion. Both HJMD and EEM have very similar hair and aricella-zoster virus (VZV) vasculopathies ac- retinal defects, but patients with EEM have additional count for almost one-third of arterial ischemic limb abnormalities. Hypotrichosis associated with V strokes in children.1 Visual complications are juvenile macular dystrophy is a rare condition with 1 rare, with previous reports occurring secondary to uni- previous report in the ophthalmology literature.7 This lateral central retinal artery2 or posterior ciliary artery3 case highlights the importance of assessing patients occlusion. We describe the first case, to our knowledge, with inherited retinal degeneration for extraocular fea- of an immunocompetent child who became blind due to tures and the fact that HJMD should be considered if bilateral ophthalmic artery occlusions secondary to prob- early-onset macular degeneration is diagnosed in the able VZV vasculopathy. context of hypotrichosis. Report of a Case. A 6-year-old boy visited his local emer- Stephanie Halford, PhD gency department with a history of sudden painless bi- Richard Holt, DPhil lateral visual loss. He was otherwise in good health apart Andrea H. Ne´meth, BSc, MBBS, DPhil, FRCP from a history of chickenpox 8 weeks previously. His fa- Susan M. Downes, MBChB, MD, FRCOphth ther had been treated for culture-negative mediastinal tuberculosis a year earlier. Initial examination in the emer- Author Affiliations: Nuffield Laboratory of Ophthalmol- gency department showed visual acuity of counting fingers ogy, Nuffield Department of Clinical Neurosciences, Uni- OU, a moderate bilateral panuveitis, and diffuse bilat- versity of Oxford, John Radcliffe Hospital (Drs Halford, eral retinal edema with sheathing of both retinal arter- Holt, Ne´meth, and Downes), Department of Clinical Ge- ies and veins. The optic discs were not swollen. Neuro- netics, Churchill Hospital (Dr Ne´meth), and Oxford Eye logical examination findings were otherwise normal. Initial Hospital (Dr Downes), Oxford, England. management aimed to treat a possible tuberculosis op- Correspondence: Dr Halford, Nuffield Laboratory of Oph- tic neuropathy and/or vasculopathy, using oral predniso- thalmology, Nuffield Department of Clinical Neurosci- lone, rifampin, pyrazinamide, and isoniazid. Initial in- ences, University of Oxford, Level 6 West Wing, John vestigations showed no abnormality on hematology and Radcliffe Hospital, Headley Way, Oxford OX3 9DU, En- biochemistry tests of peripheral blood. Cytomegalovi- gland ([email protected]). rus and VZV IgG were both detected on testing of se- Author Contributions: All authors had full access to all rum, but polymerase chain reaction results for the re- the data in the study and take responsibility for the in- spective DNA were negative. Evidence of tuberculosis tegrity of the data and the accuracy of the data analysis. infection was not found, with negative results on both Conflict of Interest Disclosures: None reported. enzyme-linked immunosorbent spot and Heaf tests and

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