Genotype–Phenotype Correlations of Nance–Horan Syndrome in Male and Female Carriers of a Novel Variant

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BACKGROUND: Nance-Horan syndrome (NHS) is a rare, frequently underdiagnosed, X-linked disease caused by mutations in the NHS gene. In males, it causes bilateral dense pediatric cataracts, dental anomalies, and facial dysmorphisms. Females traditionally have a more subtle phenotype with discrete lens opacities as an isolated feature. The objective of this case report is to describe a novel variant in NHS, as well as to discuss genotype-phenotype correlations. METHODS: Whole-exome sequencing was performed in 3 affected individuals (2 males and 1 female) with pediatric cataracts from the same family, as well as in 2 unaffected members from the same family. Ophthalmological and clinical genetic evaluations were conducted. RESULTS: The likely pathogenic variant c.3333del (p.Phe1111Leufs*9) was found in all affected individuals, as well as in one unaffected female family member. Our family was initially diagnosed with isolated hereditary cataracts, but only after the sequencing results was the phenotype revealed, with the systemic features being identified. CONCLUSIONS: This reinforces the importance of genetic testing of bilateral familial pediatric cataracts, especially since systemic features such as dental anomalies and intellectual disability may take years before they develop. Not only did genetic testing help to identify extraocular features, but it also made possible accurate family counseling essential in all pediatric cataract cases.

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