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Saadiah Goolam, Nadia Carstens, Mark Ross, David Bentley, Margarida Lopes, John Peden, Zoya Kingsbury, Trevor R Carmichael, Michele Ramsay, Susan E Williams; Posterior segment coloboma and congenital cataract in a South African family. Invest. Ophthalmol. Vis. Sci. 2016;57(12):4832. doi: https://doi.org/.
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Congenital cataracts are an important treatable cause of childhood visual disability. Non-syndromic hereditary forms may be associated with other ocular anomalies in approximately 15% of cases, usually involving the anterior segment. Inherited forms of coloboma are less frequent than the sporadic form, and are predominantly associated with systemic disease. They may also be associated with other ocular anomalies. Cataracts are much more commonly associated with iris colobomas than isolated posterior segment colobomas. The objective of this study is to report the uncommon phenotype of congenital cataract and posterior segment coloboma in a South African family and to investigate its genetic etiology.
Observational case series. DNA was extracted and whole genome sequencing was performed on six affected family members.
Twenty-six family members were included, with 20 individuals affected in an inheritance pattern consistent with autosomal dominant. Posterior segment coloboma (predominantly optic disc coloboma) was present in 17 individuals and iris coloboma in 1. Fourteen had evidence of cataract, with anterior polar cataracts in 10 and pupillary membrane remnants in 4 of these. Nystagmus was present in 17. Other features included high myopia in 8 individuals and microcornea in 3 individuals. Variant ranking identified a R208W PAX6 mutation (dbSNP rs757259413; HGMD CM930572) that was present in all 6 sequenced individuals.
This study reports on the uncommon association of congenital cataract with posterior segment coloboma in a South African family. The R208W PAX6 mutation known to be associated with aniridia is implicated in the variably expressed cataract-coloboma phenotype seen in this family. This association has not previously been described and should contribute to our understanding of the role PAX6 plays in ocular development and cataractogenesis.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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