Nance-Horan syndrome

Nance-Horan syndrome (NHS), also known as cataract-dental syndrome, is a rare X-linked genetic disorder primarily characterized by congenital cataracts, distinctive dental anomalies, and characteristic facial features. The condition is caused by mutations in the NHS gene located on chromosome Xp22.13. Males are more severely affected, presenting with dense bilateral congenital cataracts that typically cause significant visual impairment from birth, along with dental abnormalities including supernumerary incisors (extra teeth), screwdriver-shaped or cone-shaped teeth (Hutchinson teeth), and diastema (gaps between teeth). Characteristic facial features may include a long face, prominent nose, large ears, and anteverted pinnae. Approximately 20-30% of affected males also have intellectual disability, which can range from mild to moderate. Female carriers of Nance-Horan syndrome may show milder manifestations due to X-inactivation patterns. Carrier females often develop posterior Y-sutural cataracts that may not significantly impair vision, and they may have subtle dental anomalies. The ocular system is the most critically affected, as the dense cataracts in males require early surgical intervention to prevent amblyopia and optimize visual development. Additional ocular findings can include microcornea, microphthalmia, and nystagmus. There is currently no cure for Nance-Horan syndrome, and management is primarily supportive and symptomatic. Early cataract surgery is essential in affected males to maximize visual outcomes, often followed by optical correction with glasses or contact lenses and amblyopia therapy. Dental anomalies may require orthodontic treatment and restorative dental care. Children with intellectual disability benefit from early developmental intervention, special education services, and speech therapy as needed. Regular ophthalmologic and dental follow-up is recommended throughout life.

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