Hunter Syndrome
Definition
Hunter syndrome is a
hereditary disease in which the breakdown of a
mucopolysaccharide (a chemical that is widely distributed in the body outside of cells) is defective. This chemical builds up and causes a characteristic facial appearance, abnormal function of multiple organs, and in severe cases, early death.
Causes, incidence, and risk factors
Hunter syndrome is inherited as an
X-linked recessive disease. This means that women carry the disease and can pass it on to their sons, but are not themselves affected.
Because girls have two
X chromosomes, their normal X can provide a functioning gene even if their other X is defective. But because boys have an X and a Y, there is no normal X gene to fix the problem if the X is defective.
The metabolic abnormality that causes Hunter syndrome is a lack of the
enzyme iduronate-2-sulfatase. In its absence, mucopolysaccharides collect in various body tissues, causing damage.
Affected children may develop an early-onset type (severe form) shortly after age 2 that causes a large
skull, coarse facial features, profound
mental retardation,
spasticity,
aggressive behavior,
joint stiffness and death before age 20. A late-onset type (mild form) causes later and less severe symptoms.
Taken from
http://en.wikipedia.org/wiki/Hunter_syndrome