We identified a homozygous missense mutation in the noncatalytic subunit (RAB3GAP2) of RAB3GAP that results in abnormal splicing in a family with congenital cataracts, hypogonadism, and mild mental retardation (Martsolf syndrome). Recently, mutations in the catalytic subunit of RAB3GAP (RAB3GAP1), a key regulator of calcium-mediated hormone and neurotransmitter exocytosis, were reported in Warburg micro syndrome, a severe neurodevelopmental condition with overlapping clinical features. RAB3GAP is a heterodimeric protein that consists of a catalytic subunit and a noncatalytic subunit encoded by RAB3GAP1 and RAB3GAP2, respectively. We performed messenger RNA-expression studies of RAB3GAP1 and RAB3GAP2 orthologues in Danio rerio embryos and demonstrated that, whereas developmental expression of rab3gap1 was generalized (similar to that reported elsewhere in mice), rab3gap2 expression was restricted to the central nervous system. These findings are consistent with RAB3GAP2 having a key role in neurodevelopment and may indicate that Warburg micro and Martsolf syndromes represent a spectrum of disorders. However, we did not detect RAB3GAP2 mutations in patients with Warburg micro syndrome. These findings suggest that RAB3GAP dysregulation may result in a spectrum of phenotypes that range from Warburg micro syndrome to Martsolf syndrome.

Background The WHO's Vision 2020 global initiative against blindness, launched in 2000, prioritises children. Progress has been hampered by the global paucity of epidemiological data about childhood visual disability. The British Childhood Visual Impairment and Blindness Study 2 (BCVIS2) was undertaken to address this evidence gap. Methods UK-wide prospective population-based observational study of all those aged under 18 years newly diagnosed with visual impairment or blindness between Oct 1, 2015 and Nov 1 2016. Eligible children were notified simultaneously but independently by their managing ophthalmologists and paediatricians via the two national active surveillance schemes, the British Ophthalmic and Paediatric Surveillance Units. Standardised detailed data were collected at diagnosis and one year later. Incidence estimates and relative rates by key sociodemographic factors were calculated. Descriptive analyses were undertaken of underlying ophthalmic disorders and nonophthalmic comorbidities. FindingsOf 784 cases, 72% had additional non-ophthalmic impairments/disorders and 4% died within the year. Annual incidence was highest in the first year of life, 5•2 per 10,000 (95% CI 4•7-5•7) with cumulative incidence by 18 years of 10•0 per 10,000 (95% CI 9•4 to 10•8). Rates were higher for those from any ethnic minority group, the lowest quintile of socio-economic status, born preterm or with low birthweight. Only 44% had a single ophthalmic condition: disorders of the brain/visual pathways affected 48% overall. Prenatal or perinatal aetiological factors accounted for 84% of all conditions. InterpretationBCVIS2 provides a contemporary snapshot of the heterogeneity, multi-morbidity and vulnerability associated with childhood visual disability in a high income country, and the arising complex needs. These findings will facilitate developing and delivering healthcare and planning interventional research. They highlight the importance of including childhood visual disability as a sentinel event and metric in global child health initiatives.

Syndromic Hirschsprung disease has been associated with mutations in ZFHX1B, a Smad-interacting transcriptional repressor protein. Tissue in situ hybridization has demonstrated strong expression of ZFHX1B in the developing eye, suggesting that some mutations in this gene may cause visual loss. However, none of the reported mutations have been associated with an ocular phenotype. We describe a patient with Down syndrome and Hirschsprung disease with high myopia and ocular coloboma affecting the iris and retina. In addition to trisomy 21, a novel, de novo heterozygous A to G transition in exon 8 of the ZFHX1B gene was identified, which results in a R953G amino acid substitution. This abnormality was not seen in a screen of 200 chromosomes from ethnically matched, normal controls. The arginine residue at position 953 is an extremely conserved amino acid throughout evolution. This is the first report associating Hirschsprung disease and severe eye defects with a specific genetic mutation and is the first report of a mutation in ZFHX1B causing a developmental ocular anomaly.