Գլխավոր Հիվանդություններ Lysosomal acid lipase deficiency

Lysosomal acid lipase deficiency (or LAL deficiency or LAL-D) happens when the body does not produce enough active lysosomal acid lipase (LAL) enzyme. This enzyme plays an important role in breaking down fatty material (cholesteryl esters and triglycerides) in the body.[1] Infants, children and adults that suffer from LAL Deficiency experience a range of serious health problems. The lack of the LAL enzyme can lead to a build-up of fatty material in a number of body organs including the liver, spleen, gut, in the wall of blood vessels and other important organs. Very low levels of the LAL enzyme lead to LAL Deficiency, historically called Wolman disease after the physician who first described it. LAL Deficiency typically affects infants in the first year of life. The accumulation of fat in the walls of the gut in early onset disease leads to serious digestive problems including malabsorption, a condition in which the gut fails to absorb nutrients and calories from food. Because of these digestive complications, affected infants usually fail to grow and gain weight at the expected rate for their age (failure to thrive). As the disease progresses, it can cause life-threatening liver dysfunction or liver failure. Until 2015 there was no treatment, and very few infants with LAL-D survived beyond the first year of life. In 2015 an enzyme replacement therapy, sebelipase alfa was approved in the US and EU. The therapy was additionally approved in Japan in 2016.

Classification and cause Lysosomal acid lipase deficiency is a genetic disease that is autosomal recessive. It is an inborn error of metabolism that causes a lysosomal storage disease. The condition is caused by a mutation of the LIPA gene, which is responsible for the gene coding of the lysosomal lipase protein (also called lysosomal acid lipase or LAL), which results in a loss of the protein's normal function. When LAL functions normally, it breaks down cholesteryl esters and triglycerides in low density lipoprotein particles into free cholesterol and free fatty acids that the body can reuse; when LAL doesn't function, cholesteryl esters and triglycerides build up in the liver, spleen and other organs. The accumulation of fat in the walls of the gut and other organs in leads to serious digestive problems including malabsorption, a condition in which the gut fails to absorb nutrients and calories from food, persistent and often forceful vomiting, frequent diarrhea, foul-smelling and fatty stools (steatorrhea), and failure to grow. Lysosomal acid lipase deficiencies occur when a person has defects (mutations) in both copies of the LIPA gene. Each parent of a person with LAL deficiency carries one copy of the defective LIPA gene. With every pregnancy, parents with a son or daughter affected by LAL deficiency have a 1 in 4 (25%) chance of having another affected child. A person born with defects in both LIPA genes is not able to produce adequate amounts of the LAL enzyme. Prevention or Screening Because LAL deficiency is inherited, each sibling of an affected individual has a 25% chance of having pathological mutations in LAL genes from both their mother and their father, a 50% chance of having a pathological mutation in only one gene, and a 25% chance of having no pathological mutations. Genetic testing for family members and genetic prenatal diagnosis of pregnancies for women who are at increased risk are possible if family members carrying pathological mutations have been identified. Outcomes Infants with LAL deficiencies typically show signs of disease in the first weeks of life and if untreated, die within 6–12 months due to multi-organ failure. Older children or adults with LAL-D may remain undiagnosed or be misdiagnosed until they die early from a heart attack or stroke or die suddenly of liver failure. The first enzyme replacement therapy was approved in 2015. In those clinical trials nine infants were followed for one year; 6 of them lived beyond one year. Older children and adults were followed for 36 weeks. Epidemiology Depending on ethnicity and geography, prevalence has been estimated to be between 1 in 40,000 and 1 in 300,000; based on these estimates the disease may be underdiagnosed. Jewish infants of Iraqi or Iranian origin appear to be most at risk based on a study of a community in Los Angeles in which there was a prevalence of 1 in 4200.

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