In affected males, the primary physical characteristic is the presence of dense clouding of the lens (cornea) of both eyes at birth (congenital bilateral cataracts). The cataracts usually result in blurred vision and severely decreased clearness or clarity of vision (visual acuity). Vision loss can potentially be profound. Males with Nance-Horan syndrome may have additional eye abnormalities, including a very small cornea (microcornea); involuntary movements of the eyes (nystagmus), and/or misalignment of the eyes (strabismus). In some cases, the entire eye may be abnormally small (microphthalmia) and/or the upper eyelid may droop (ptosis).
Males with Nance-Horan syndrome may also have several dental abnormalities such as unusually shaped, extra (supernumerary) teeth, absence of some teeth (dental agenesis), impacted teeth or unusually wide spaces (diastema) between some of the teeth. The front teeth, or incisors, are usually tapered and 'screwdriver-shaped'. The teeth in the back of the mouth may be cone-shaped, rounded, or cylindrical.
In many males with Nance-Horan syndrome, other physical findings may also occur. Distinctive facial features may be present, but may be subtle. The ears may be flared forward and unusually prominent. Affected males may also have a large, prominent nose with a high, narrow nasal bridge, a narrow prominent jaw, and sometimes a long, narrow face.
Some males with Nance-Horan syndrome may also experience delays the skills necessary for coordinating muscular and mental activity. In addition, some reports suggest that approximately 20 to 30 percent of affected males may have varying levels of intellectual disability, which is usually mild to moderate; but in some cases can be severe.Females who carry a single copy of the mutation in the NHS gene may develop some symptoms of the disorder. However, symptoms are usually milder and more variable than those seen in males. Affected females may have abnormally small corneas (microcornea) and/or some clouding of the cornea. Vision may be normal, or there may be slightly decreased visual acuity. Without appropriate treatment, clouding of the cornea can lead to total cataracts later in life. Females often have some dental abnormalities, such as abnormally-shaped front teeth and/or unusually wide spaces between some of the teeth. Affected females usually do not develop intellectual disability.
The Human Phenotype Ontology (HPO) provides the following list of features that have been reported in people with this condition. Much of the information in the HPO comes from Orphanet, a European rare disease database. If available, the list includes a rough estimate of how common a feature is (its frequency). Frequencies are based on a specific study and may not be representative of all studies. You can use the MedlinePlus Medical Dictionary for definitions of the terms below.
|Signs and Symptoms||Approximate number of patients (when available)|
|Abnormal nasal morphology||90%|
|Prominent nasal bridge||90%|
|Intellectual disability, moderate||80%|
|Abnormality of the metacarpal bones||50%|
|Increased number of teeth||50%|
|Aplasia/Hypoplasia affecting the eye||7.5%|
|Posterior Y-sutural cataract||-|
|Short phalanx of finger||-|
|Supernumerary maxillary incisor||-|
|X-linked dominant inheritance||-|
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My nephew was diagnosed with Nance-Horan syndrome. He was born with cataracts, supernumerary teeth, and facial dysmorphism. He doesn't have intellectual disabilities. My sister is the carrier and she has some of the characteristics; but much less severe than her son. No other family members have features of the syndrome. Is it possible that the genetic defect started with her? And what are the chances of my sister having a child without the defect? Is it possible to be a carrier and not show any outward signs of the syndrome? See answer