Other Names for this Disease
- Cataract dental syndrome
- Cataract X-linked with Hutchinsonian teeth
- Mesiodens cataract syndrome
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 provides the following list of signs and symptoms for Nance-Horan syndrome. If the information is available, the table below includes how often the symptom is seen in people with this condition. You can use the MedlinePlus Medical Dictionary to look up the definitions for these medical terms.
The Human Phenotype Ontology (HPO) has collected information on how often a sign or symptom occurs in a condition. Much of this information comes from Orphanet, a European rare disease database. The frequency of a sign or symptom is usually listed as a rough estimate of the percentage of patients who have that feature.
The frequency may also be listed as a fraction. The first number of the fraction is how many people had the symptom, and the second number is the total number of people who were examined in one study. For example, a frequency of 25/25 means that in a study of 25 people all patients were found to have that symptom. Because these frequencies are based on a specific study, the fractions may be different if another group of patients are examined.
Sometimes, no information on frequency is available. In these cases, the sign or symptom may be rare or common.
- Nance-Horan Syndrome. National Organization for Rare Disorders (NORD). 2011; http://www.rarediseases.org/rare-disease-information/rare-diseases/byID/1055/viewAbstract. Accessed 8/22/2011.