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MKS1-related disorders

What are MKS1-related Disorders?

Mutations in MKS1 are found in 2 different inherited syndromes:

Meckel-Gruber syndrome is caused by mutations in at least 13 different genes, including MKS1. Meckel-Gruber syndrome is an inherited genetic condition that causes central nervous system (CNS) malformations, fluid-filled sacs (cysts) in the kidney and polydactyly (extra fingers and toes). Other birth defects, including defects of the heart, cleft lip and cleft palate, and abnormalities of the liver and genitalia, are also features of Meckel-Gruber syndrome. Due to the severity of symptoms, those affected with Meckel-Gruber syndrome are stillborn or die soon after birth. The common birth defects associated with Meckel-Gruber syndrome can often be seen on prenatal ultrasound.

In some cases, mutations in this gene may cause a more mild condition called Bardet-Biedl syndrome (BBS13). Bardet-Biedl syndrome is an inherited disease that causes vision problems, kidney abnormalities, genital anomalies, extra fingers or toes, and mild obesity, among other symptoms. About half of people with the disease have developmental delay or mental disability.

How common are MKS1-related Disorders?

Meckel-Gruber syndrome affects an estimated 1/13,250 - 1/140,000. It is more common in certain specific populations such as the Finnish (1/9000) and Belgians (1/3000).

Bardet-Biedl syndrome is rare, affecting about 1 in 100,000 in North America and 1 in 125,000 in Europe. It is more or less common in specific populations such as Kuwaiti Bedouins (1 in 13,500), residents of Newfoundland, Canada (1 in 17,500), and the Swiss (1 in 160,000). It is estimated that MKS1 accounts for 4.5% of all Bardet-Biedl syndrome.

How are MKS1-related Disorders treated?

There is no cure for Meckel-Gruber syndrome. For those affected, treatment is supportive.

For those individuals affected with Bardet-Biedl syndrome, extra fingers and toes can often be surgically removed in childhood. The vision and kidney problems associated with the disease can be treated in the standard fashion by medical specialists. If kidney problems reach life-threatening levels, dialysis and/or kidney transplantation may be necessary. Diet and exercise can help control obesity. In women, vaginal malformations can be surgically corrected.

What is the prognosis for a person with an MKS1-related Disorder?

Meckel-Gruber syndrome is a lethal condition and prognosis is poor. Those affected are either stillborn or die in the first few hours or days of life.

Kidney disease is a major cause of early death for people with Bardet-Biedl syndrome. However, a majority of individuals may have a normal or near-normal life expectancy with some impairments.