Lipidoses Health Article

Definition

Lipidoses are heredity disorders, passed from parents to their children, characterized by defects of the digestive system that impair the way the body uses fat from the diet. When the body is unable to properly digest fats, lipids accumulate in body tissues in abnormal amounts.

Description

The digestion, storage, and use of fats from foods is a complex process that involves hundreds of chemical reactions in the body. In most people, the body is already programmed by its genetic code to produce all of the enzymes and chemicals necessary to carry out these functions. These genetic instructions are passed from parents to their offspring during reproduction.

People with lipidoses are born without the genetic codes needed to tell their bodies how to complete a particular part of the fat digestion process. In most of these disorders, the body does not produce a certain enzyme or chemical. Over 30 different disorders of fat metabolism are related to genetic defects. Although the defects are passed from parents to children, the parents often do not have the disorders themselves.

The symptoms, available treatments, and long-term consequences of these conditions vary greatly. Some of the conditions become apparent shortly after the infant is born; in others, symptoms may not develop until adulthood. For most of the lipidoses, diagnosis is suspected based on the symptoms and family history. Blood tests, urine tests, and tissue tests can be used to confirm the diagnosis. Genetic testing can be used, in some cases, to identify the defective gene. Some of these disorders can be controlled with changes in the diet, medications, or enzyme supplements. For many, no treatment is available. Some may cause death in childhood or contribute to a shortened life expectancy. Some of the most common or most serious lipidoses are discussed below.

Fabry's disease

Although patients with Fabry's disease usually survive to adulthood, they are at increased risk for stroke, heart attacks, and kidney damage.

Gaucher disease

The pain and deformities associated with symptoms can make coping with this illness very challenging for individuals and families. With treatment and control of symptoms, people with Type 1 Gaucher disease may lead fairly long and normal lives. Most infants with Type 2 die before the age of 2. Children with Type 3 Gaucher disease may survive to adolescence and early adulthood.

Krabbe's disease

Children born with Krabbe's disease die in infancy.

Niemann-pick disease

Treatment consists of supportive care to deal with symptoms and the development of complications. Bone marrow transplantation is being investigated as a possible treatment. Low-cholesterol diets may be helpful for patients with Types C and D.

Refsum's disease

A diet free of phytanic acid (found in dairy products, tuna, cod, haddock, lamb, stewed beef, white bread, white rice, boiled potatoes, and egg yolk) can reduce some of the symptoms. Plasmapheresis, a process where whole blood is removed from the body, processed through a filtering system, and then return to the body, may be used to filter phytanic acid from the blood.

Tay-sachs disease

Tay-Sachs disease (TSD) is a fatal condition caused by a deficiency of the enzyme hexosaminidase A (Hex-A). The defective gene that causes this disorder is found in roughly 1 in 250 people in the general population. However, certain populations have significantly higher rates of TSD. French-Canadians living near the St. Lawrence River and in the Cajun regions of Louisiana are at higher risk of having a child with TSD. The highest risk seems to be in people of Eastern European and Russian Jewish (Ashkenazi) descent. Tay-Sachs disease has a recessive pattern of inheritance, and approximately 1 in every 27 people of Jewish ancestry in the United States carries the TSD gene. Symptoms develop in infancy and are due to the accumulation of a fatty acid compound in the nervous system. Early symptoms include loss of vision and physical coordination, seizures, and mental retardation. Eventually, the child develops problems with breathing and swallowing. Blindness, paralysis, and death follow.

Wolman's disease

Death generally occurs before six months of age.

Niemann-Pick disease

Patients with Type A NPD usually die within the first year and a half of life. Type B patients generally live to adulthood but suffer from significant liver and lung problems. With Types C and D NPD, there is significant nervous system damage leading to severe muscle spasms, seizures, and eventually, to coma and death. Some patients with Types C and D die in childhood, while less severely affected patients may survive to adulthood.

Tay-Sachs disease

Children born with Tay-Sachs disease become increasingly debilitated; most die by about age four.