Most cases of familial LPL deficiency are identified during childhood, usually before the age of 10. In approximately 25 percent of patients, the disorder is identified during the first year of life. Some affected individuals may not be identified until adulthood. For example, some women may not be diagnosed until after becoming pregnant or when they begin taking contraceptive medication.
The severity of familial LPL deficiency varies depending upon the degree of chylomicronemia, which fluctuates depending upon the amount fat in an individual’s diet. The main symptoms are Abdominal pain, pancreatitis, eruptive xanthomas and hepatosplenomegaly.
The most common symptom of familial LPL deficiency is episodic Abdominal pain. The severity of Abdominal pain can vary, ranging from mild to severe and, in some people, can be incapacitating. The pain may be located in the upper, central region (epigastric area) of the abdomen and can radiate to cause back pain. In some people, the pain may be widespread (diffuse) and can potentially resemble acute abdomen (peritonitis). In the past, this has led to unnecessary surgery.
Abdominal pain in individuals with familial LPL deficiency may result from recurrent episodes of inflammation of the pancreas (pancreatitis). The pancreas is a small gland located behind the stomach. The pancreas secretes enzymes that travel to the intestines to aid in digestion and hormones that have specialized roles in the body. The main symptom of pancreatitis is pain, which is sometimes intense, and is most often felt in the upper left side or middle of the abdomen. Pancreatitis can also cause Nausea, sweating, Weakness, Chills, clammy skin, and mild yellowing of the skin or whites of the eyes (jaundice). Some individuals will develop acute, recurrent pancreatitis, which can potentially be lethal.
Chronic pancreatitis can be associated with additional complications including diabetes, hardening of the pancreas due to the accumulation of calcium salts (pancreatic calcification) and stools containing excess amounts of fat causing them to be frothy, foul smelling and to float (steatorrhea). However, these complications are unusual in individuals with familial LPL deficiency. Even in individuals with recurrent episodes of pancreatitis, such complications rarely develop until middle age. Although rare, pancreatitis in LPL deficiency can cause severe, life-threatening complications.
Enlargement of the liver and spleen (hepatosplenomegaly) can also occur, especially in infants and young children. The degree of enlargement varies, often in conjunction with the amount of fat in the diet. Hepatosplenomegaly is caused by the accumulation of a special type of macrophage. Macrophages are white blood cells that ingest foreign or harmful substances. In familial LPL deficiency, macrophages ingest excess triglyceride and transform into foam cells. Foam cells are specialized macrophages that attempt to deal with excess fat in the body and usually contain fatty materials. Foam cells in individuals with familial LPL deficiency abnormally accumulate in the bone marrow, liver and spleen.
Approximately 50 percent of affected individuals develop eruptive cutaneous xanthomas, which are skin lesions make up of certain fats (lipids). Xanthomas may appear as raised, reddish-yellow bumps or nodules on the skin. They often occur on the buttocks, knees and outer arms. Individuals lesions may measure about 1 millimeter in size, but xanthomas often cluster and may grow together (coalesce) to form larger lesions. Eruptive xanthomas are generally not painful or tender, unless they develop on an area of the body where they suffer repeated trauma or abrasion. Xanthomas usually appear within a few days after triglyceride levels in the plasma have begun to increase. They may contain a greasy, yellowish substance and sometimes a milky fluid. Xanthomas will disappear over a period of weeks to months as the amount of triglyceride in the plasma decreases. The persistent presence of xanthomas in individuals with familial LPL deficiency indicates inadequate therapy to lower triglyceride levels.
In the presence of excessive fatty substances in the circulation the small arteries (arterioles) and small veins (venules) in the outer parts of the retina and the back of the eyeball (fundus) may appear pale pink upon examination by an eye specialist (ophthalmologist). This condition may be referred to as “lipemia retinalis”. The change is related to the degree of fatty build up (i.e., large chylomicrons), which causes incoming light to scatter. This discoloration is reversible and does not affect the vision of individuals with familial LPL deficiency.
Additional symptoms have been reported in some individuals with familial LPL deficiency including a variety of reversible neuropsychiatric findings such as depression, memory loss and dementia.
Some individuals with familial LPL deficiency have developed premature atherosclerosis, which is characterized by thickening and obstruction of various blood vessels due to the accumulation of fatty material, potentially causing coronary heart disease or peripheral vascular disease. However, most researchers do not believe that individuals with familial LPL deficiency have an increased risk of developing atherosclerosis.