The Potential Involvement of the Pituitary Transcription Factor HESX1

156

Case Report

The potential involvement of the pituitary transcription factor HESX1 in the septo-optic-pituitary hypoplasia with normal septum pellucidum but life-threatening neonatal phenotype Hipoplasia septo-óptica-hipofisária em paciente com septo pelúcido normal porém com risco de morte neonatal e a participação potencial do fator de transcrição hipofisário HESX1 Natasha Guimarães Ludwig1,2 Marcos Antônio Dias1,3 Mateus Nóbrega Aoki4 Renan Lovato1,5 Marla KarineAmarante4 Maria Angelica Ehara Watanabe4 Tânia Longo Mazzuco1,6

ABSTRACT Septo-optic dysplasia (SOD) is a heterogeneous developmental syndrome involving brain midline anomalies associated with pituitary-hypothalamic, ophthalmological and neurodevelopmental dysfunctions. The phenotype is highly variable making the disease classification difficult. We report a case of severe neonatal hypopituitarism leading to the discovery of cerebral malformations and optic nerve hypoplasia characterizing the SOD-like syndrome. Besides the mild MRI features with normal septum pellucidum, this patient exhibited a life-threatening endocrine phenotype. Rare mutations have been described in the HESX1 gene, which encodes a homeobox transcription factor, associated with various pituitary hormone deficiencies combined with SOD. We isolated the DNA coding region from this candidate gene for sequence analysis. In this 7-year follow-up case report and preliminary genetic screening we discuss diagnostic investigation after management of first clinical presentation, highlighting the neuroimaging on this syndrome. Keywords: septo-optic dysplasia, septum pellucidum, hypopituitarism, HESX1 RESUMO A displasia septo-óptica (DSO) é uma síndrome do desenvolvimento considerada heterogênea, pois envolve anomalias da linha média do cérebro associadas a disfunções oftalmológicas, neurológicas e do eixo hipotálamo-hipófise. O fenótipo é altamente variável dificultando a classificação da doença. Relatamos um caso de hipopituitarismo neonatal grave que levou à descoberta de malformações cerebrais e hipoplasia do nervo óptico, sendo caracterizada assim a síndrome DSO-like. Mesmo em presença de um septo pelúcido normal e com poucas alterações na ressonância magnética, este paciente apresentou um fenótipo endócrino de alto risco de morte no período neonatal. Mutações genéticas têm sido raramente descritas no HESX1 e estão associadas a várias deficiências hormonais hipofisárias combinadas com a DSO. O gene HESX1 codifica um fator de transcrição pertencente à classe de genes chamados homeobox. A partir deste gene candidato, foi isolada a região codificadora no DNA para análise por sequenciamento. Este relato de caso com seguimento clínico de 7 anos e estudo genético preliminar apresenta uma discussão da investigação diagnóstica a partir do quadro inicial, destacando as alterações de neuroimagem encontradas nesta síndrome. Palavras Chave: displasia septo-óptica, septo pelúcido, hipopituitarismo, HESX1

Introduction (SP) and optic nerve hypoplasia3, and 15 years latter it was described in association with hypopituitarism7. The absence of SP is not mandatory for the diagnosis of SOD and only one The septo-optic dysplasia (SOD) was first described by de third of the patients present the complete triad4. The diagnosis Morsier in 1954 in patients with absent septum pellucidum

1Neuroendocrinology Research Group, Health Science Center (CCS), Universidade Estadual de Londrina (UEL)/Paraná (PR), Brazil 2Scientific initiation scholarship of Fundação Araucária/IC-2012, UEL/PR, Brazil 3Neurosurgery Division, University Hospital, UEL/PR, Brazil 4Laboratory of Molecular Genetic-Immunology, Biological Science Center, UEL/PR, Brazil 5Scientific initiation scholarship of CNPq/PIBIC-2008, UEL/PR, Brazil 6Health Sciences Postgraduate Course, CCS/UEL/PR, Brazil

Received Sept 30, 2013. Accepted Nov 28, 2013 Ludwig NG, Dias MA, Aoki MN, Lovato R, Amarante MK, Watanabe MAE, Mazzuco TL. - The potential involvement of the pituitary transcription factor J Bras Neurocirurg 24 (2): 156-160, 2013 HESX1 in the septo-optic-pituitary hypoplasia with normal septum pellucidum but life-threatening neonatal phenotype 157

Case Report

is done when found two of the following characteristics: bilateral optic disc hypoplasia, but neither midline facial 1) midline neuroradiologic alterations, 2) uni or bilateral defects nor remarkable findings were detected on neurological hypoplasia of the optic nerve, 3) hypopituitarism9. Absence examination. In addition, the patient presented micropenis of SP and hypoplasia or agenesis of the corpus callosum are and bilateral micro-orchidism. The biochemical findings included among the possible midline neuroradiologic findings. suggested conjugated hyperbilirubinaemia (total bilirubin 4.6 mg/dL; direct bilirubin 2 mg/dL) and combined thyrotroph, The incidence of the SOD is 1/10,000 live births and the corticotroph, somatotroph and gonadotroph deficits (freeT4 prevalence is the same in males and females15. The condition 0.51 ng/dL; cortisol 0.3 μg/dL assessed during hypoglycemia; is usually idiopathic but some familial cases have been IGF-1 26.4ng/mL; GH 3.67 ng/mL; LH, FSH and testosterone described. Recent studies have shown association of isolated below detection limits). The patient had no symptoms of optic nerve hypoplasia or SOD and young maternal age while diabetes insipidus. Hypoglycemia resolved after introduction gene mutations are rare4. The HESX1 gene, also known as Rpx of glucocorticoid replacement (prednisolone 5mg/m2/day) and (Rathke’s pouch homeobox gene) is expressed in the early levo-thyroxine was then associated to the hormone replacement forebrain primordium and Rathke’s pouch6. The initial pituitary therapy. Brain magnetic resonance imaging (MRI) performed development is controlled by the HESX1 transcripts which are at 2 months of age revealed pituitary hypoplasia. Since the detected between the 6.5th and 15.5th embryonic day17. The posterior pituitary function remained preserved, the first failure of the primary cells to differentiate or proliferate during clinical diagnosis was congenital anterior panhypopituitarism the pituitary embryogenesis results in congenital alterations, with bilateral amaurosis. evidenced by hormone deficiencies and/or anatomical changes in the spectrum of the SOD syndrome10. HESX1-deficient After the neonatal period, recombinant human GH replacement mouse embryos present a reduction in the prosencephalic tissue, therapy was initiated when his growth rate fell to 1 cm/year anophthalmia or microphthalmia, abnormalities of the corpus (at 1.5 year-old), resulting with adequate growth response for callosum and SP, and small anterior pituitary disconnected to the next years. New head imaging study defined better some the posterior lobe2. The midline brain defects in the mutant features (Figure 1): the pituitary stalk absence and rudimentary mice shows a phenotypic resemblance with the SOD in optic chiasm supported the diagnosis of bilateral optic humans. Another types of HESX1-mutant mice have shown nerve hypoplasia (ONH). Images did not show significant that the expression domain of human HESX1 is comparable malformations as cortical dysplasia/schizencephaly or to that in the mouse and includes the ventral forebrain and absence of SP. Severe pituitary anomaly was confirmed by the Rathke’s pouch15. Until now, the genetic screening of more observation of stalk agenesis, anterior pituitary hypoplasia and than 800 patients with SOD and pituitary hormone deficiency ectopic posterior pituitary (Figure 1 A,B). have found genetic mutations in less than 1% of the subjects, During the follow-up, the neurocognitive development confirming the rarity of mutations of the HESX12. remained normal and no motor deficits or new episodes of seizure attacks were observed. He developed all neuro- psychomotor skills as expected for congenitally blind children Case Report receiving adapted health care, rehabilitation and education. Levo-thyroxine, glucocorticoid, growth hormone and testosterone replacements have been monitored and adjusted A breastfed 29 days-old boy was admitted to the pediatric when appropriated. emergency with severe dehydration, generalized tonic-clonic seizures and capillary glycemia 16 mg/dl, within 20 days of According to the algorithm of combined pituitary hormone discharge from the maternity hospital. At birth, he had jaundice, deficiency (CPHD) genetic screening using a phenotype- hypoglycemia and absent visual fixation. The main emergency based strategy, we chose the main candidate gene for this treatment was continuous intravenous glucose infusion case study12. Peripheral blood was collected for DNA analysis which was maintained for several days. Ophthalmological of the HESX1 gene in a first attempt to identify the genetic assessment revealed vertical and horizontal nystagmus and defect causing CPHD associated with neuro-ophtalmological

Ludwig NG, Dias MA, Aoki MN, Lovato R, Amarante MK, Watanabe MAE, Mazzuco TL. - The potential involvement of the pituitary transcription factor J Bras Neurocirurg 24 (2): 156-160, 2013 HESX1 in the septo-optic-pituitary hypoplasia with normal septum pellucidum but life-threatening neonatal phenotype 158

Case Report

abnormalities in the present case. The polymerase chain be presented as a syndrome with midline forebrain defects reaction (PCR) using intron-flanking primers, followed by such as in the septo-optic dysplasia. Association with neuro- direct sequencing of amplified genomic DNA, allowed us to ophthalmological midline defects characterizes a syndrome isolate the coding sequence fragments of the HESX1 gene. with a broad variety of phenotypes8,14. In the present case, early Variants were found in the exons 1 and 3 after analysis of clinical signs of hypopituitarism on neonatal period constituted aligned DNA sequence chromatograms for the NCBI database a life-threatening condition and preceded the suspicion of SOD reference sequence (NM_003865.2). These variants in the neuro-ophtalmological symptoms. The diagnosis of congenital HESX1 coding sequence do not match any of the previously hypopituitarism is often not straightforward; in the presented described mutations and therefore require additional molecular case, prolonged neonatal jaundice, hypoglycemia and the study. The family history was negative for endocrine disorders, presence of micropenis suggests congenital hypopituitarism. dysmorphic features or metabolic conditions. There was no The large spectrum of malformations in the SOD also includes consanguinity between the parents. corpus callosum hypoplasia or absence and occasionally other cerebral abnormalities such as schizencephaly or cortical dysplasia. However, some patients have no cerebral midline malformations and do not qualify for the diagnosis by definition. Such heterogeneous features have resulted in some disagreement as to how SOD is defined and categorized. The following classification is based on distinct anatomic subsets1,5,11,16.

Table 1: SOD Classification

SOD type I presence of schizencephaly

SOD type II complete absence of SP but no schizencephaly

SOD type III corpus callosum absence

malformations of cortical development other than SOD-Plus schizencephaly a mild phenotype with ONH and pituitary anomaly SOD-like but normal SP Figure 1: Neuroimaging at 2-year old age. A, Sagittal 3D Fiesta weighted MRI demonstrating optic chiasm (OC) atrophy and anterior pituitary (AP) hypoplasia, in addition to the following normal structures: corpus callosum (CC) and septum pellucidum. (SP). B, Sagittal T1 weighted MRI revealing anterior pituitary hypoplasia According to this classification, the clinical picture of our (AP) and ectopic posterior pituitary (PP). C, Coronal T2 weighted MRI showing the patient suggests a SOD-like phenotype. Interestingly, the age septum pellucidum. D, Axial T1 weighted MRI showing bilateral optic nerves (ON) of diagnosis in SOD-like patients was higher (median age 5.19 atrophy. years, 12 patients) in the few cases of SOD-like that have been reported14. The work-up in patients with SOD can be complex depending Discussion on the phenotype. The appropriate clinical management requires a multidisciplinary team for the neuropediatric, endocrine, ophtalmological, neuroradiological and genetic questions18. While the etiology of SOD remains unclear, some Pituitary aplasia or hypoplasia causing hypopituitarism can cases can be caused by specific genetic abnormalities because

Case Report

HESX1 gene mutations have been well characterized in Agenesia of the olfactory lobe (lateral telencephaloschisis) association with this syndrome13. Moreover, many data suggest and of the callous and anterior commissures (median telencephaloschisis); olfacto-genital dysplasia]. Schweiz Arch an important role for HESX1 in forebrain, midline and pituitary Neurol Psychiatr. 1954;74(1-2):309-61 2,6,8,17 development in mouse and human . Genetic variants found 4. Garcia-Filion P, Borchert M. Optic nerve hypoplasia syndrome: in this work need to be confirmed in the affected patient and a review of the epidemiology and clinical associations. Curr family members. Then, the true contribution of HESX1 defects Treat Options Neurol. 2013;15(1):78-89 to the etiology of the presented SOD-like syndrome could be 5. Gasparetto EL, Warszawiak D, de Carvalho Neto A, Benites Filho PR, Bruck I, Antoniuk S. Septo-optic dysplasia plus: case established by in-depth genetic analysis. report. Arq Neuropsiquiatr. 2003;61(3A):671-6 In conclusion, we presented a child with SOD-like syndrome 6. Hermesz E, Mackem S, Mahon KA. Rpx: a novel anterior- restricted homeobox gene progressively activated in the having congenital anterior pituitary deficiency and ONH. prechordal plate, anterior neural plate and Rathke’s pouch of the Aspects on neuroimaging (mild MRI features with normal mouse embryo. Development. 1996;122(1):41-52 septum pellucidum) and normal neurocognitive development 7. Hoyt WF, Kaplan SL, Grumbach MM, Glaser JS. Septo-optic does not predict the pituitary function. The presentation of dysplasia and pituitary dwarfism. Lancet. 1970;1(7652):893-4 this case report emphasizes the early diagnosis of congenital 8. Kelberman D, Dattani MT. Hypothalamic and pituitary hypopituitarism, which is crucial as patients undergo severe development: novel insights into the aetiology. European Journal of Endocrinology. 2007;157 Suppl 1:S3-14 acute hypoglycemia and chronic adrenal, growth, gonad 9. Morishima A, Aranoff GS. Syndrome of septo-optic-pituitary and thyroid insufficiencies that may lead to devastating dysplasia: the clinical spectrum. Brain and Development. consequences for neurological development and even survival. 1986;8(3):233-9 In addition, molecular analysis might contribute to expand our 10. Parks JS, Brown MR, Hurley DL, Phelps CJ, Wajnrajch MP. understanding of the clinical heterogeneity and inheritance Heritable disorders of pituitary development. Journal of Clinical Endocrinology and Metabolism. 1999;84(12):4362-70 patterns of hypopituitarism and central nervous system malformations. 11. Patel L, McNally RJ, Harrison E, Lloyd IC, Clayton PE. Geographical distribution of optic nerve hypoplasia and septo- optic dysplasia in Northwest England. J Pediatr. 2006;148(1):85- 8 12. Reynaud R, Castinetti F, Galon-Faure N, Albarel-Loy F, Saveanu A, Quentien MH, et al. [Genetic aspects of growth hormone Acknowledgements deficiency]. Arch Pediatr. 2011;18(6):696-706 13. Reynaud R, Gueydan M, Saveanu A, Vallette-Kasic S, Enjalbert The authors wish to thank staff and medical residents, including A, Brue T, et al. Genetic screening of combined pituitary hormone deficiency: experience in 195 patients. J Clin Endocrinol Metab. ML Oliveira, LF Bopp, G Toyama, CCS Izzo, JR Tristão and 2006;91(9):3329-36 R Radaeli for the early draft of this case report in a poster 14. Riedl S, Vosahlo J, Battelino T, Stirn-Kranjc B, Brugger presentation, and the patient’s guardian for the written consent PC, Prayer D, et al. Refining clinical phenotypes in septo- to publish this manuscript. optic dysplasia based on MRI findings. Eur J Pediatr. 2008;167(11):1269-76 15. Sajedi E, Gaston-Massuet C, Signore M, Andoniadou CL, Kelberman D, Castro S, et al. Analysis of mouse models carrying the I26T and R160C substitutions in the transcriptional References repressor HESX1 as models for septo-optic dysplasia and hypopituitarism. Dis Model Mech. 2008;1(4-5):241-54 16. Sener RN. Septo-optic dysplasia associated with cerebral cortical dysplasia (cortico-septo-optic dysplasia). J Neuroradiol. 1. Barkovich AJ, Fram EK, Norman D. Septo-optic dysplasia: MR 1996;23(4):245-7 imaging. Radiology. 1989;171(1):189-92 17. Sheng HZ, Westphal H. Early steps in pituitary organogenesis. 2. Dattani MT, Martinez-Barbera JP, Thomas PQ, Brickman JM, Trends in Genetics. 1999;15:236-40 Gupta R, Martensson IL, et al. Mutations in the homeobox gene HESX1/Hesx1 associated with septo-optic dysplasia in human 18. Trabacca A, De Rinaldis M, Gennaro L, Losito L. Septo-optic and mouse. Nature Genetics. 1998;19(2):125-33 dysplasia-plus and dyskinetic cerebral palsy in a child. Neurol Sci. 2012;33(1):159-63. 3. De Morsier G. [Studies in cranio-encephalic dysraphia. I.

Case Report

Corresponding Author

Profa. Dra. Tânia Longo Mazzuco, Disciplina de Endocrinologia, Departamento de Clínica Médica, Centro de Ciências da Saúde, Universidade Estadual de Londrina Av. Robert Koch 60, CEP 86038-440 Londrina PR, Brasil. E-mail: [email protected] ou [email protected]