FG Syndrome - a Genetic Disorder Passed from Mother to Son

FG syndrome, which is also known as Opitz-Kaveggia Syndrome and Keller syndrome, is a rare genetic disorder in which most sufferers have symptoms that can include mental retardation, low muscle tone, brain abnormalities , seizures, large head, characteristic facial features, large intestinal and anal abnormalities, constipation, short stature, fixed joints, broad big toes, and light and dark skin streaking.

It is believed that FG Syndrome is caused by a mutation of genes on the X chromosome by interrupting the gene's normal function in the brain as well as in the digestive tract, and muscle tissue. A female will not develop FG Syndrome, but can be a carrier. The condition is passed down from mother to son. A mother who is a carrier has a 50% chance of having a son with FG Syndrome and a 50% chance of having a daughter who is a carrier. A father who has FG Syndrome has a 100% chance of having a daughter who is a carrier and a 0% chance of having a son with FG Syndrome

The symptoms can vary greatly even with FG Syndrome patients who belong to the same family, although mental retardation is the most prevalent, striking 97% of FG Syndrome patients.

There is no test for FG Syndrome, but research from Dr. Silvain Briault of the University of Tours in France has led to the discovery of a gene, Xq13, that seems to be linked to FG Syndrome in some families and evidence that another gene, Xq28 may be involved. The way the research is heading it looks like Xq13 is associated with a more severe form of the syndrome and Xq28 with a milder form. However, the research is still in the beginning stages and it has a long way to go before it can be counted on as a diagnostic tool. In order to reach a diagnosis of FG Syndrome the patient will be referred to a medical geneticist who will look for signs such as large heads, big foreheads, a front cowlick of hair, wide-spaced eyes, extra eye folds (short, palpebral fissures), constipation, and an outgoing, talkative personality as well as broad thumbs and big toes, small ears, fine/thinning hair, fused fingers, minor back bone abnormalities, cleft lip and palate, heart defects, and fetal fingertip pads. Many of these symptoms can occur in any number of genetic conditions. Only an expert can put all of the piece together.

The prognosis for a FG Syndrome patient varies greatly depending on the type and severity of the symptoms. About 30% of those will sever heart defects and anal abnormalities will not live beyond the age of 2. However, most FG Syndrome patients do not have that level of severity.

Sources:
Frequently Asked Questions about FG Syndrome

FG Syndrom Family Alliance

FG Syndrom Information