Nance-Horan Syndrome: Further Delineation of the Affected Male and the Female Carrier Phenotypes.

Nance-Horan syndrome (NHS; OMIM 302350) is a rare, X-linked syndrome characterized by bilateral congenital cataracts leading to profound vision loss, specific dental anomalies including characteristic screwdriver blade-shaped incisors, facial anomalies, and intellectual disability. It is caused by deleterious loss of function variants or deletions involving the NHS gene at Xp22.13. Heterozygous females often present with similar, but less severe features than affected males. We describe a relatively large cohort of eight new patients with NHS, including two patients with microdeletions including NHS who had classical presentations, and provide detailed descriptions of the clinical findings for both affected males and females. The spectrum of clinical features in NHS is variable and can be mild, in particular for females, and the condition can remain undiagnosed. This report contributes to the delineation of the phenotypic and genotypic findings associated with this condition.