NORD gratefully acknowledges Annick Toutain, MD, PhD, Service of Genetics Center, Hospital-University of Tours, Francois Rabelais University, for assistance in the preparation of this report.
Nance-Horan syndrome is a rare genetic disorder that may be evident at birth (congenital). It is primarily characterized by abnormalities of the teeth and clouding of the lens of the eyes (congenital cataracts), resulting in poor vision. Additional eye (ocular) abnormalities are also often present, such as unusual smallness of the front, clear portion of the eye through which light passes (microcornea) and involuntary, rapid, rhythmic eye movements (nystagmus). In some affected individuals, the disorder may also be associated with additional physical abnormalities and/or intellectual impairment. The range and severity of symptoms may vary greatly from one person to another, including among affected members of the same family.
Nance-Horan syndrome is inherited as an X-linked trait that it is usually fully expressed in males only. However, females who carry a single copy of the disease gene (heterozygotes) may manifest some of the symptoms and findings associated with the disorder. These may include microcornea and/or clouding of the lens of the eyes (posterior sutural cataract). Symptoms are less severe than those of affected males, potentially causing only slightly decreased clearness or clarity of vision (visual acuity). In some patients, abnormalities of the teeth may also be present. Intellectual impairment rarely occurs in females.
(Please note that some of these organizations may provide information concerning certain conditions potentially associated with this disorder [e.g., visual impairment, dental abnormalities, intellectual disability, etc.].)
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