Nance-Horan syndrome

What causes Nance-Horan syndrome?

Nance-Horan syndrome is caused by a mutation in the NHS gene, which is located on the X chromosome. Some patients have losses (deletions) of part of the chromosome X short arm (p) within the region involving the NHS gene and other genes that are located in this region. These patients may have more problems and the problems may be more serious.

Last updated on 05-01-20

How is Nance-Horan syndrome inherited?

Nance-Horan syndrome is inherited as an X-linked dominant trait. In X-linked dominant inheritance, both males and females can be affected by a condition. However, affected males tend to have more severe features than females.

X-linked conditions result from mutations of a gene located on an X chromosome. Females have two X chromosomes, but males have one X chromosome and one Y chromosome. In females, disease traits resulting from the abnormal copy of a gene on one X chromosome can be 'masked' by the normal copy of the gene on the other X chromosome. Because only one functioning X chromosome is required in males and females, one of the X chromosomes in each cell of a female is essentially 'turned off,' usually in a random pattern (X chromosome inactivation). Therefore, if the X chromosome with the gene mutation is activated in some cells, female carriers may have some mild features of the disorder. However, since males only have one X chromosome, they will likely fully express a condition if they inherit a gene mutation that is located on the X chromosome.

Last updated on 05-01-20

Is it possible for Nance-Horan syndrome to _not_ be inherited (i.e. the gene mutation started in the affected person)?

When a gene mutation happens for the first time in a family member and is not inherited from a parent, this is called a de novo mutation. Although we were unable to find specific information about de novo mutations causing Nance-Horan syndrome, we recommend that your sister discuss this with a genetics professional, who can help her to understand how this condition might be inherited in your family. Below, we have provided resources for finding a genetics professional in your area.

Last updated on 05-01-20

What is the chance that someone with Nance-Horan syndrome will pass this condition on to their children?

Males with Nannce-Horan syndrome will transmit the gene to all their daughters, who are carriers, but never to their sons. Women who are carriers for this condition have a 50 percent chance of transmitting the carrier condition to their daughters and a 50 percent risk of transmitting Nance-Horan syndrome to their sons.

Last updated on 05-01-20

What is Nance-Horan syndrome?

Nance-Horan syndrome is a rare genetic disorder that may be evident at birth. It is characterized by teeth abnormalities and cataracts, resulting in poor vision. Additional eye abnormalities are also often present, including a very small cornea and nystagmus. In some cases, the condition may also be associated with physical abnormalities and/or intellectual disability. The range and severity of symptoms may vary greatly from one person to another, even among affected members of the same family. Nance-Horan syndrome is caused by a mutation in the NHS gene and is inherited as an X-linked dominant trait, which means that both males and females can be affected, but males often have more severe symptoms.The treatment is directed toward the specific symptoms that are apparent in the individual.

Last updated on 05-01-20

Name: The Arc of the United States 1825 K Street, NW Suite 1200
Washington, DC, DC, 20006, United States
Phone: +1-202-534-3700 Toll Free: 1-(800) 433-5255 Fax : +1-202-534-3731 Email: Url:
Name: National Association for Parents of Children with Visual Impairments (NAPVI) P.O. Box 317
Watertown, MA, 02471, United States
Phone: 617-972-7441 Toll Free: 800-562-6265 Fax : 617-972-7444 Email: Url:
Name: National Federation of the Blind 200 East Wells Street at Jernigan Place
Baltimore, MD, 21230, United States
Phone: 410-659-9314 Fax : 410-685-5653 Email: Url:

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