NORD gratefully acknowledges Jakub Tolar, MD, PhD, Tulloch Chair in Stem Cell Biology, Genetics and Genomics, Director, Stem Cell Institute, Professor, Blood and Marrow Transplantation, Department of Pediatrics, University of Minnesota, for the assistance in the preparation of this report.
Wolman disease is a type of lysosomal acid lipase (LAL) deficiency; a rare genetic disorder characterized by complete absence of an enzyme known as lysosomal acid lipase (LIPA or LAL). This enzyme is required to breakdown (metabolize) certain fats (lipids) in the body. Without the LIPA enzyme, certain fats may abnormally accumulate in the tissues and organs of the body causing a variety of symptoms. Wolman disease may cause bloating or swelling of the stomach (abdominal distention), vomiting, and significant enlargement of the liver or spleen (hepatosplenomegaly). Life-threatening complications often develop during early childhood. Wolman disease is caused by mutations in the lysosomal acid lipase (LIPA) gene and is inherited as an autosomal recessive trait.
Wolman disease is the most severe expression of LAL deficiency; a milder form of LAL deficiency is known as cholesteryl ester storage disease (CESD). (see the Related Disorders section of this report).LIPA gene mutations that cause CESD result in some enzyme activity, whereas LIPA gene mutations that cause Wolman disease produce an enzyme with no residual activity or no enzyme at all. Genetic and biochemical evidence indicates that CESD and Wolman disease are distinguished by residual lysosomal acid lipase activity.
The symptoms of Wolman disease usually become apparent shortly after birth, usually during the first few weeks of life. Affected infants may develop bloating or swelling of the stomach (abdominal distention) and may have significant enlargement of the liver and spleen (hepatosplenomegaly). Scarring (fibrosis) of the liver may also occur. In some cases, fluid may accumulate in the abdominal cavity (ascites).
Infants with Wolman disease have serious digestive abnormalities including malabsorption, a condition in which the intestines fail to absorb nutrients and calories form food. Malabsorption associated with Wolman disease causes persistent and often forceful vomiting, frequent diarrhea, foul-smelling, fatty stools (steatorrhea) and malnutrition. Because of these digestive complications, affected infants usually fail to grow and gain weight at the expected rate for their age and sex (failure to thrive).
Enlargement of the liver and spleen and protrusion of the abdomen can cause umbilical hernia, a condition in which the contents of the stomach may push through an abnormal opening or tear in the abdominal wall near the bellybutton. Additional symptoms may also occur in Wolman disease including yellowing of the skin, mucous membranes and whites of the eyes (jaundice), a persistent low-grade fever, and poor muscle tone (hypotonia). Infants may exhibit delays in the development of motor skills.
A distinct finding associated with Wolman disease is the hardening of adrenal gland tissue due to the accumulation of calcium (calcification). The adrenal glands are located on top of the kidneys and produce two hormones called epinephrine and norepinephrine. Other hormones produced by the adrenal glands help to regulate the fluid and electrolyte balance in the body. Calcification of the adrenal glands is not detectable by physical examination, but can be seen with x-ray study. Calcification may prevent the adrenal glands from producing enough essential hormones and can affect metabolism, blood pressure, the immune system and other vital processes of the body.
Infants with Wolman disease may experience the loss of previously acquired skills required the coordination of muscle and motor skills (psychomotor regression). The symptoms of Wolman disease often get progressively worse eventually leading to life-threatening complications during infancy including extremely low levels of circulating red blood cells (severe anemia), liver (hepatic) dysfunction or failure, and physical wasting away and severe weakness often associated with chronic disease and marked by weight loss and loss of muscle mass (cachexia or inanition).
Wolman disease is caused by mutations in the lysosomal acid lipase (LIPA) gene. The LIPA gene contains instructions for producing the enzyme lysosomal acid lipase. This enzyme is essential for breaking down (metabolizing) certain fats in the body, especially cholesterol (specifically cholesteryl esters) and to a lesser degree triglycerides. Without proper levels of this enzyme, these fats abnormally accumulate in and damage various tissues and organs of the body. Mutations in the LIPA gene that cause Wolman disease result in the lack of production of the LIPA enzyme or production of a defective, inactive form of the LIPA enzyme.
Wolman disease is inherited as an autosomal recessive trait. Genetic diseases are determined by the combination of genes for a particular trait that are on the chromosomes received from the father and the mother.
Recessive genetic disorders occur when an individual inherits two copies of an abnormal gene for the same trait, one from each parent. If an individual inherits one normal gene and one gene for the disease, the person will be a carrier for the disease but usually will not show symptoms. The risk for two carrier parents to both pass the altered gene and have an affected child is 25% with each pregnancy. The risk to have a child who is a carrier like the parents is 50% with each pregnancy. The chance for a child to receive normal genes from both parents is 25%. The risk is the same for males and females.
Parents who are close relatives (consanguineous) have a higher chance than unrelated parents to both carry the same abnormal gene, which increases the risk to have children with a recessive genetic disorder.
Wolman disease is an extremely rare disorder that affects males and females in equal numbers. More than 50 cases have been reported in the medical literature. However, cases may go undiagnosed or misdiagnosed making it difficult to determine the disorder’s true frequency in the general population. Wolman disease is named after one of the physicians who first identified the disorder in the medical literature in 1956.
A diagnosis of Wolman disease may be suspected in newborn infants based upon identification of characteristic symptoms such as abnormally enlarged liver and gastrointestinal problems. A diagnosis may be confirmed by a thorough clinical evaluation, a detail patient history (including family history) and specialized tests that reveal absence or deficient activity of the enzyme lysosomal lipase acid (LIPA) in certain cells and tissues of the body. Molecular genetic testing for mutations in the LIPA gene is also available.
In December 2015, the U.S. Food and Drug Administration (FDA) approved Kanuma (sebelipase alfa) as the first treatment for people with lysosomal acid lipase (LAL) deficiency.
Other treatment is directed toward the specific symptoms that are apparent in each individual. Treatment may require the coordinated efforts of a team of specialists. Proper nutrition can be maintained intravenously. If the adrenal glands are not functioning properly, medications may be used to supplement the hormones normally produced by these glands.
A team approach for individuals with Wolman disease may be necessary and may include special social support and other medical services. Genetic counseling is recommended for affected individuals and their families.
In the medical literature, a few children with Wolman disease were treated with hematopoietic stem cell transplantation (HSCT). Hematopoietic stem cells are specialized cells found in the bone marrow (the soft spongy material found in long bones). These blood stem cells grow and eventually develop into one of the three main types of blood cells– red blood cells, white blood cells or platelets. A transplant is done to replace the bone marrow (and consequently the whole blood system) of an affected individual with marrow from a person who does not have a particular disorder. The healthy cells produced by the new marrow contain sufficient levels of lysosomal acid lipase required to breakdown cholesterol and triglycerides. Individuals with Wolman disease treated with hematopoietic stem cell transplantation have shown dramatic improvement of existing symptoms and avoidance of additional complications such as liver failure. Researchers speculate that early diagnosis and prompt treatment with a hematopoietic stem cell transplant increases the chances of preserving liver function and preventing cognitive decline. More research is necessary to determine the long-term safety and effectiveness of this potential therapy for infants with Wolman disease. Hematopoietic stem cell transplants are not without drawbacks. The procedure is expensive and carries the risk of serious complications including graft-versus-host disease and other long-term and late effects.
Researchers have been studying enzyme replacement therapy for lysosomal storage diseases such as Wolman disease. Enzyme replacement therapy involves replacing a missing enzyme in individuals who are deficient or lack the particular enzyme in question. Synthetic versions of missing enzymes have been developed and used to treat individuals with certain lysosomal diseases including Hurler syndrome, Fabry syndrome and Gaucher disease.
Gene therapy is also being studied as another possible approach to therapy for some lysosomal storage disorders. In gene therapy, the defective gene present in a patient is replaced with a normal gene to enable the production of active enzyme and prevent the development and progression of the disease in question. Given the permanent transfer of the normal gene, which is able to produce active enzyme at all sites of disease, this form of therapy is theoretically most likely to lead to a “cure.” However, at this time, there are many technical difficulties to resolve before gene therapy can succeed.
Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov . All studies receiving U.S. Government funding, and some supported by private industry, are posted on this government web site.
For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:
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