X - linked infantile nystagmus (nystagmus X-linked infantile) - Gen FRMD7.  

The X - linked infantile nystagmus is a disorder characterized by abnormal eye movements. In people with this disorder, nystagmus is present at birth or develops within the first six months of life. Abnormal eye movements may worsen when the affected person feels anxious or tries to stare directly at an object. Nystagmus severity varies, even among those affected within the same family.

This process is due to mutations in the gene FRMD7, located on the long arm of the X chromosome (Xq26.2), encoding a protein whose exact function is unknown. This protein is found in many tissues, but is most abundant in areas of the brain that control eye movement (for example, midbrain and cerebellum) and in the retina and is likely to play a role in the development of nerve cells in these areas of the brain and retina.

There are more than 35 mutations in the gene causing infantile nystagmus FRMD7 X - linked Most of these mutations change the amino acids in protein. Mutations in the gene lead to the synthesis of a protein is unstable and can not perform their normal function. It is believed that the lack of functional proteins disrupts the development of nerve cells in the retina and brain areas that control eye movement. It is likely that the abnormal development of these nerve cells cause involuntary movements from side to side of the eye that are characteristic of the disease.

Nystagmus child is inherited in an X - linked pattern A disease is X - linked if the mutated gene that causes the disorder is located on the X chromosome in males, an altered copy of the gene in each cell is enough to cause disease. In women, an altered copy of the gene in each cell can cause disease, although women express less affected than males affected intense symptoms. About half of women with only one copy of the altered gene in each cell FRMD7 have no symptoms of the disease.

Tests in IVAMI: in IVAMI perform detection of mutations associated with X - linked infantile nystagmus, by complete PCR amplification of exons FRMD7 gene, and subsequent sequencing.

Samples recommended: EDTA blood collected for separation of blood leukocytes, or impregnated sample card with dried blood (IVAMI may mail the card to deposit the blood sample).