A severe progressive oculodentodigital dysplasia due to compound heterozygous GJA1 mutation

Clinical Characteristics of Autosomal Dominant GJA1 Missense Mutation Linked to Oculodentodigital Dysplasia in a Korean Family

PURPOSE

We aimed to present a comprehensive assessment of the ophthalmic characteristics of genetically confirmed oculodentodigital dysplasia (ODDD) in 4 members of a single Korean family across 3 generations.

PATIENTS AND METHODS

The characteristics of 4 affected ODDD patients were evaluated. Comprehensive ophthalmic and medical examinations were performed in 3 patients including the proband, together with genetic analysis, and retrospective chart review was conducted for an affected ancestor. For genetic analysis, targeted gene panel sequencing was conducted using genomic DNA extracted from peripheral blood.

RESULTS

All affected individuals in this family showed shared ophthalmic abnormalities of microcornea, microphthalmia, elevated intraocular pressure, and shallow anterior chamber, all of which have been reported as typical ocular features of ODDD. Myopic refractive error despite short axial length and thick cornea were highlighted as new findings of ODDD. Facial abnormalities were common in all affected members, but their fingers were normal. Severity of glaucoma was different among the affected individuals and seemed to depend on elevation of intraocular pressure, which occurred in narrow, but open-angle. Genetic analysis revealed the presence of c.119C>T (p.Ala40Val) in GJA1, which is responsible for ODDD, but not found in the control population.

CONCLUSIONS

This report describes detailed ocular characteristics in a genetically confirmed ODDD family, including unreported findings of thick cornea and myopic refractive error despite short axial length. The ocular features derived from the A40V mutation in GJA1 showed complete penetrance, suggesting a possible role of Cx43 in regulation of IOP and pathogenesis of glaucoma.

Oculodentodigital Dysplasia: A Case Report and Major Review of the Eye and Ocular Adnexa Features of 295 Reported Cases

Oculodentodigital dysplasia (ODDD) is a rare genetic disorder associated with a characteristic craniofacial profile with variable dental, limb, eye, and ocular adnexa abnormalities. We performed an extensive literature review to highlight key eye features in patients with ODDD and report a new case of a female patient with a heterozygous missense GJA1 mutation (c.65G>A, p.G22E) and clinical features consistent with the condition. Our patient presented with multiple congenital anomalies including syndactyly, microphthalmia, microcornea, retrognathia, and a small nose with hypoplastic alae and prominent columella; in addition, an omphalocele defect was present, which has not been reported in previous cases. A systematic review of the published cases to date revealed 91 literature reports of 295 individuals with ODDD. There were 73 different GJA1 mutations associated with these cases, of which the most common were the following missense mutations: c.605G>A (p.R202H) (11%), c.389T>C (p.I130T) (10%), and c.119C>T (p.A40V) (10%). Mutations most commonly affect the extracellular-1 and cytoplasmic-1 domains of connexin-43 (gene product of GJA1), predominately manifesting in microphthalmia and microcornea. The syndrome appears with an approximately equal sex ratio. The most common eye features reported among all mutations were microcornea, microphthalmia, short palpebral fissures, and glaucoma.

Oculodentodigital Dysplasia: A Hypomyelinating Leukodystrophy with a Characteristic MRI Pattern of Brain Stem Involvement

Oculodentodigital dysplasia, a rare genetic disorder caused by mutations in the gene encoding gap junction protein 1, classically presents with typical facial features, dental and ocular anomalies, and syndactyly. Oligosymptomatic patients are common and difficult to recognize, in particular if syndactyly is absent. Neurologic manifestation occurs in approximately 30% of patients, and leukodystrophy or T2 hypointensity of gray matter structures or both have been noted in individual patients. To investigate MR imaging changes in oculodentodigital dysplasia, we retrospectively and systematically reviewed 12 MRIs from 6 genetically confirmed patients. Diffuse supratentorial hypomyelination, T2-hypointense Rolandic and primary visual cortex, and symmetric involvement of middle cerebellar peduncle, pyramidal tract, and medial lemniscus was present in all, T2-hypointense pallidum and dentate nucleus in 2 patients each. This consistent, characteristic pattern of diffuse supratentorial hypomyelination and brain stem involvement differs from other hypomyelinating and nonhypomyelinating leukodystrophies with brain stem involvement, and its recognition should trigger genetic testing for oculodentodigital dysplasia.

A novel truncation mutation in GJA1 associated with open angle glaucoma and microcornea in a large Chinese family

PURPOSE

To identify genetic defects in a large family with open angle glaucoma (OAG) and microcornea.

METHODS

Genomic DNA was prepared from leukocytes of 15 individuals from three generations of a Chinese family, including seven individuals with OAG and microcornea, one with microcornea alone, and seven healthy individuals. Whole exome sequencing was performed on genomic DNA of the proband. Candidate variants were obtained through multiple steps of bioinformatics analysis and validated by Sanger sequencing and segregation analysis.

RESULTS

Exome sequencing detected a candidate variant in GJA1, a novel truncation mutation (c.791_792delAA, p.K264Ifs*43). This mutation was present in all seven individuals with OAG and microcornea and the individual with microcornea alone, but not in the seven unaffected relatives in the family. It was not present in 1394 alleles from 505 unrelated controls without glaucoma and 192 normal controls. Extraocular signs were not observed in seven out of the eight individuals; only one was affected with dental enamel hypoplasia and syndactyly.

CONCLUSIONS

A novel truncation mutation in GJA1 is associated with OAG and microcornea in a Chinese family. This suggests that GJA1 should be included as a candidate gene for glaucoma.

Cardiac arrhythmia and death of teenager linked to rare genetic disorder diagnosed at autopsy

A 17-year-old male adolescent sustained cardiac arrest after participating in a wrestling match, where he was thrown down. He had no pulse, and cardiopulmonary resuscitation was immediately initiated along with application of an automatic external defibrillator. Upon arrival of emergency medical services, an electrocardiogram showed the patient to be in ventricular tachycardia, torsades, and ventricular fibrillation. The patient was ultimately transported to the hospital and, with ACLS protocol being performed, was resuscitated to a junctional rhythm with bradycardia and borderline prolonged QT. His hospital stay was characterized by refractory cardiac failure, and 2 days after the incident, a decision was made to remove him from life support. At autopsy, there were no external or internal injuries that could be considered a contributing cause of death. On external examination, observations were made about the decedent's facial features including his nose, eyes, ears, fingers, and toes. A careful review of the decedent's medical history was initiated to reveal birth defects including syndactyly of the third and fourth digit of the upper extremity as well as complete lack of dental enamel. A tentative diagnosis of oculodentodigital dysplasia was made and confirmed by genetic testing of heart muscle taken from the decedent. This case report examines the rare association of oculodentodigital dysplasia with cardiac arrhythmia as well as places emphasis on the features of the disorder that can aid in its diagnosis.

Dominant De Novo Mutations in GJA1 Cause Erythrokeratodermia Variabilis et Progressiva, without Features of Oculodentodigital Dysplasia

Genetic investigation of inherited skin disorders has informed understanding of skin self-renewal, differentiation, and barrier function. Erythrokeratodermia variabilis et progressiva (EKVP) is a rare, inherited skin disease characterized by transient figurate patches of erythema, localized or generalized scaling, and frequent palmoplantar keratoderma. By employing exome sequencing, we show that de novo missense mutations in GJA1 (gap junction protein alpha 1) cause EKVP. The severe, progressive skin disease in EKVP subjects with GJA1 mutations is distinct from limited cutaneous findings rarely found in the systemic disorder oculodentodigital dysplasia, also caused by dominant GJA1 mutations. GJA1 encodes connexin 43 (Cx43), the most widely expressed gap junction protein. We show that the GJA1 mutations in EKVP subjects lead to disruption of Cx43 membrane localization, and aggregation within the Golgi. These findings reveal a critical role for Cx43 in epidermal homeostasis, and provide evidence of organ-specific pathobiology resulting from different mutations within GJA1.

Three novel GJA1 missense substitutions resulting in oculo-dento-digital dysplasia (ODDD) - further extension of the mutational spectrum

Oculodentodigital dysplasia (ODDD) is a clinically variable genetic disorder caused by mutations of the GJA1 gene, predominantly inherited in an autosomal dominant fashion. In rare cases ODDD can also exhibit autosomal recessive mode of inheritance. The phenotype of ODDD comprises craniofacial (short and narrow palpebral fissure, thin, narrow nose with hypoplastic alae nasi), dental (oligodontia, hypoplastic enamel), and digital abnormalities (syndactyly of finger 4/5, hypoplastic phalanges). Ocular manifestation is typical and involves microphthalmia, microcornea, glaucoma, congenital malformations of iris or vitreous, ectopic pupils or strabismus. To date, only 67 GJA1 mutations have been described to underlie ODDD and most of them (i.e. 97%) represent missense substitutions. In this report, we describe three (two familial and one sporadic) non-consanguineous cases presenting with ODDD features in whom we identified novel missense heterozygous mutations of the GJA1 gene: c.317T>G (p. L106R), c.G139C (p.D47H), and c.C257A (p.S86Y). The first two mutations were inherited from an affected parent, whereas the latter one occurred de novo. The mutations affect highly conserved amino acid residues located in the different portions of the GJA1 protein. Our report broadens the spectrum of probably pathogenic mutations associated with ODDD phenotype and demonstrates that the amino acid substitutions at highly conserved positions 47, 86, 106 may affect protein functioning and lead to the development of this syndrome. Together with molecular data, we provide a brief clinical description of the affected individuals.

Gap junctions in inherited human disorders of the central nervous system

CNS glia and neurons express connexins, the proteins that form gap junctions in vertebrates. We review the connexins expressed by oligodendrocytes and astrocytes, and discuss their proposed physiologic roles. Of the 21 members of the human connexin family, mutations in three are associated with significant central nervous system manifestations. For each, we review the phenotype and discuss possible mechanisms of disease. Mutations in GJB1, the gene for connexin 32 (Cx32) cause the second most common form of Charcot-Marie-Tooth disease (CMT1X). Though the only consistent phenotype in CMT1X patients is a peripheral demyelinating neuropathy, CNS signs and symptoms have been found in some patients. Recessive mutations in GJC2, the gene for Cx47, are one cause of Pelizaeus-Merzbacher-like disease (PMLD), which is characterized by nystagmus within the first 6 months of life, cerebellar ataxia by 4 years, and spasticity by 6 years of age. MRI imaging shows abnormal myelination. A different recessive GJC2 mutation causes a form of hereditary spastic paraparesis, which is a milder phenotype than PMLD. Dominant mutations in GJA1, the gene for Cx43, cause oculodentodigital dysplasia (ODDD), a pleitropic disorder characterized by oculo-facial abnormalities including micropthalmia, microcornia and hypoplastic nares, syndactyly of the fourth to fifth fingers and dental abnormalities. Neurologic manifestations, including spasticity and gait difficulties, are often but not universally seen. Recessive GJA1 mutations cause Hallermann-Streiff syndrome, a disorder showing substantial overlap with ODDD. This article is part of a Special Issue entitled: The Communicating junctions, composition, structure and functions.