menkes syndrome

Menkes disease

Menkes disease (also called the kinky hair disease or Menkes kinky hair syndrome) is a disorder that affects copper levels in the body. It is characterized by sparse and coarse hair, growth failure, and deterioration of the nervous system. Onset of Menkes syndrome typically begins during infancy. Signs and symptoms of this disorder include weak muscle tone (hypotonia), sagging facial features, seizures, mental retardation, and developmental delay. The patients have brittle hair and metaphyseal widening. In rare cases, symptoms begin later in childhood and are less severe. It is a X-linked recessive disorder, and is therefore considerably more common in males: females require two defective alleles to develop the disease.

It was originally described by Menkes et al. in 1962.

Occipital horn syndrome (sometimes called X-linked cutis laxa), is a mild form of Menkes syndrome that begins in early to middle childhood. It is characterized by calcium deposits in a bone at the base of the skull (occipital bone), coarse hair, and loose skin and joints.

Epidemiology

The estimated incidence of Menkes disease is between 1 in 30,000 and 1 in 250,000.

Symptoms

Affected infants may be born prematurely. Symptoms appear during infancy and are largely a result of abnormal intestinal copper absorption with secondary deficiency in copper-dependent mitochonrial enzymes. Normal or slightly slowed development may proceed for 2 to 3 months, and then there will be severe developmental delay and a loss of early developmental skills. Menkes Disease is also characterized by seizures, failure to thrive, subnormal body temperature, and strikingly peculiar hair, which is kinky, colorless or steel-colored, and easily broken. There can be extensive neurodegeneration in the gray matter of the brain. Arteries in the brain can also be twisted with frayed and split inner walls. This can lead to rupture or blockage of the arteries. Weakened bones (osteoporosis) may result in fractures.

Treatment

Early treatment with subcutaneous (under the skin) or intravenous (in a vein) injections of copper supplements (in the form of acetate salts) may be of some benefit. Other treatment is symptomatic and supportive.

Genetics

Mutations in the ATP7A gene cause Menkes syndrome. As the result of a mutation in the ATP7A gene, copper is poorly distributed to cells in the body. Copper accumulates in some tissues, such as the small intestine and kidneys, while the brain and other tissues have unusually low levels. The decreased supply of copper can reduce the activity of numerous copper-containing enzymes that are necessary for the structure and function of bone, skin, hair, blood vessels and the nervous system.

This condition is inherited in an X-linked recessive pattern. A condition is considered X-linked if the mutated gene that causes the disorder is located on the X chromosome (one of the two sex chromosomes). In males, who have only one X chromosome, one altered copy of the gene in each cell is sufficient to cause the condition. In females, who have two X chromosomes, a mutation must be present in both copies of the gene to cause the disorder. Males are affected by X-linked recessive disorders much more frequently than females. A striking characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons.

About one-third of cases result from new mutations in the gene and occur in people with no history of the disorder in their family.

References

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