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Meckel-Gruber Syndrome (MKS)
Monday, 18 August 2003
Tuesday, 12 July 2005

What

Meckel-Gruber syndrome (MKS) is a rare genetic disorder that is characterized by abnormal development of the kidneys, central nervous system and extremities. Babies born with MKS also have abnormal facial features.

Who

The incidence of MKS varies from 1 in 13,250 to 1 in 140,000 births. MKS can occur in all ethnicities although there is a reported increased incidence in the Belgian population (1 in 3,000), the Finnish population (1 in 9,000), and the Ashkenazi Jewish population (1 in 50,000). Males and females are affected equally.

Signs and Symptoms

Infants born with MKS can have any of the following symptoms, but the three major findings of encephalocele, polycystic kidneys and polydactyly are the defining characteristics (as described further below). An occipital encephalocele occurs when there is an opening in the back of the skull which allows part of the brain to go through. The brain is usually poorly developed and other problems with the central nervous system can exist. These infants often have small heads with a downward-sloping forehead because of the underdeveloped brain. Their facial features may be unusual with small eyes, malformed ears, a small jaw and clefts (openings) of the lip or roof of the mouth. The mouth can be long and they may have teeth when they are born. The kidneys develop multiple large cysts causing the kidneys not to function properly. This results in low amniotic fluid during pregnancy which leads to underdeveloped lungs. At birth, this causes difficulty breathing. An extra finger or toe (called postaxial polydactyly) is a very common finding. These babies are also very small at birth, weighing and measuring less than most babies of the same age. Other problems include heart, liver, and spleen abnormalities. There can be incomplete development of the genitalia such as abnormalities of the uterus or vagina in girls, abnormalities of the testes in boys, or an anus that is not open.

Possible Causes

Meckel-Gruber syndrome is caused by changes (mutations) in one of several genes. These genes are called MKS1, MKS2, and MKS3. These genes are located on chromosomes 17, 11, and 8, respectively. MKS is inherited in an autosomal recessive manner.

Diagnosis

The diagnosis of Meckel-Gruber syndrome can be made prenatally (during pregnancy) by ultrasound to look for a small head size, an encephalocele, and abnormal kidneys. Amniocentesis during pregnancy (taking fluid from the sac surrounding the fetus) can also be performed to measure the level of alpha fetoprotein (AFP). A high AFP level is found with babies who have abnormal development of the central nervous system. After birth, studies such as ultrasound can be done to check for kidney, liver, and brain abnormalities. The abnormal facial features and extra fingers or toes can also be present.

Treatment

Currently, there is no cure or treatment for Meckel-Gruber syndrome.

Prognosis

Unfortunately, infants born with Meckel-Gruber syndrome are stillborn or die within a few hours to days after birth. The leading cause of death is due to the underdeveloped lungs. A few infants live for a few weeks and succumb to kidney and liver failure. Very few infants have been known to survive for several months. Parents of an infant born with MKS may be asked to have the blood of their baby and their own blood sent for genetic testing. This could help to confirm the diagnosis of the infant and to determine the risk for the parents of having another child affected with MKS.

Connect with other parents

In the spirit of community and support, Madisons Foundation offers the unique service of connecting parents of children with rare diseases. If you would like to be connected to other parents of children with this disease, please fill out this brief form.

Weblinks

The Compassionate Friends
Provides grief support for families after the death of a child.

Helping After Neonatal Death (HAND)
A non-profit organization that provides resources for support groups.

Smart Perspective
A website for parents with information about the disease.

Google Search for Meckel-Gruber Syndrome (MKS)

References and Sources

OMIM: Meckel Syndrome. McKusick, V. www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=249000 Gene Reviews: Meckel-Gruber Syndrome. www.geneclinics.org/servlet/access?id=8888891&testtype=both&qry=meckel&submit=Search&showglossarylinks=yes&db=genetests&fcn=b&res=&key=FT3lWAKV4FbF5&testtype=both&type=e&ls=c&grp=b&submit=Search www.icondata.com/health/pedbase/files/MECKEL-G.HTM www.emedicine.com/ped/topic1390.htm