Extreme corneal fragility and thinning, which have a high risk of catastrophic spontaneous rupture, are the cardinal features of brittle cornea syndrome (BCS), an autosomal-recessive generalized connective tissue disorder. Enucleation is frequently the only management option for this condition, resulting in blindness and psychosocial distress. Even when the cornea remains grossly intact, visual function could also be impaired by a high degree of myopia and keratoconus. Deafness is another common feature and results in combined sensory deprivation. Using autozygosity mapping, we identified mutations in PRDM5 in families with BCS. We demonstrate that regulation of expression of extracellular matrix components, particularly fibrillar collagens, by PRDM5 is a key molecular mechanism that underlies corneal fragility in BCS and controls normal corneal development and maintenance. ZNF469, encoding a zinc finger protein of hitherto undefined function, has been identified as a quantitative trait locus for central corneal thickness, and mutations in this gene have been demonstrated in Tunisian Jewish and Palestinian kindreds with BCS. We show that ZNF469 and PRDM5, two genes that when mutated cause BCS, participate in the same regulatory pathway.

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.

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