Familial Lipoprotein Lipase Deficiency (LPLD) is a rare inherited condition, in which the normal breakdown of fats in the body is disrupted due to defects in the lipoprotein lipase.
Fats in our diet are broken down in the small intestine into small fatty fragments, such as cholesterol and triglycerides. Within cells lining the intestines, these small fragments are immediately ‘re-assembled’ into particles called ‘chylomicrons’ allowing them to be transported in the bloodstream to other body parts to provide energy, maintain healthy cells, and build hormones. Lipoprotein lipase (LPL) is a key protein (enzyme) that ensures triglycerides are ‘unloaded’ from chylomicrons. Absence of this enzyme leads to increased blood triglyceride and chylomicron levels and, therefore, to most of the signs and symptoms of LPLD.
Alternative names are:
• Familial hyperchylomicronemia
• Familial fat-induced hypertriglyceridemia
• Familial LPL deficiency
• Hyperchylomicronemia, Familial
• Familial Hyperlipoproteinemia Type I
• Lipase D deficiency
• LIPD deficiency
• Lipoprotein Lipase Deficiency, Familial
Source: lpldeficiency; Genetics Home Reference
In children, signs and symptoms may include increased irritability and failure to thrive.
Children and adults may suffer:
• Abdominal pain (may appear as colic in infancy)
• A swollen abdomen because of an enlarged liver and/or spleen
• Loss of appetite
• Pain in the muscles and bones (musculoskeletal pain)
• Recurrent acute pancreatitis
• Reduced or absent lipoprotein lipase
• Skin xanthomas
• Increased cholesterol and/or triglyceride level
• Whitish-yellow nodules
• White fatty retinal deposits
Sources: lpldeficiency; Medlineplus
Familial LPLD is usually caused by a defective gene (the LPL gene), encoding for an enzyme called lipoprotein lipase. Persons with LPLD lack this enzyme and their body cannot break down fat from digested food. Fat particles called chylomicrons build up in the blood.
This condition is inherited in an autosomal recessive pattern, the parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.
Risk factors include a family history of lipoprotein lipase deficiency.
Sources: Source: lpldeficiency; Genetics Home Reference
Many of the symptoms of LPLD are unspecific, and may not immediately be recognized as being caused by LPLD. Patients with LPLD, therefore, may not be diagnosed for many years. There are a number of other closely related conditions, which involve raised blood fat levels (generally known as hyperlipidemia), which may be confused with LPLD. There are also other conditions, including inherited diseases, that may lead to (recurrent) acute pancreatitis, and more diseases that cause repeated abdominal pain, or an increase in the size of the spleen and liver. An accurate diagnosis is important in ensuring appropriate care and management of the disease.
Specific tests include:
• Genetic testing for alterations in the LPL gene
• Testing the activity of lipoprotein lipase (LPL) in the blood
• Blood fat profiling. Historically, diagnosis in individuals with raised blood fat levels (hyperlipidemia) has been based on profiling the types of fats and /or fat transporter proteins present in a blood sample. LPLD is associated with raised blood triglyceride, raised blood cholesterol and raised chylomicrons. Repeated profiling, may be used to assess whether a change in diet, or the administration of a lipid lowering drug, has any impact on blood lipids. This may provide the doctor with further clues as to whether LPLD is involved or not.
Persons with this condition who follow a very low-fat diet may live into adulthood.
• The standard treatment aims to control the symptoms and blood triglyceride levels with a very low-fat diet.
• The management of LPLD-related pancreatitis is generally the same as that for pancreatitis from other causes. This may include strong pain relief medication, nil-by-mouth, and ensuring that the patient remains well hydrated.
• Alternative approach for treatment of LPLD is a gene therapy.