MONDO_0009387 (familial lipoprotein lipase deficiency) is a rare genetic disorder is which a person lacks the enzyme lipoprotein lipase, a protein needed to break down fat molecules. Deficiency of this enzyme prevents affected individuals from properly digesting certain fats. This results in the accumulation of fatty droplets called chylomicrons in the blood and an increase in the blood concentration of triglycerides. Symptoms include episodes of abdominal pain, recurrent inflammation of the pancreas (pancreatitis), abnormal enlargement of the liver and/or spleen (hepatosplenomegaly), and the development of skin lesions known as erruptive xanthomas. Familial lipoprotein lipase deficiency is caused by changes (mutations) in the LPL gene. It is inherited in an autosomal recessive pattern. Treatment aims to control symptoms and blood triglyceride levels with a very low-fat diet. Treatment for individual symptoms (i.e. pancreatitis) involves following established treatment guidelines. Also known as: Fredrickson type I hyperlipoproteinemia, Fredrickson type I lipaemia, LPL deficiency, familial LPL deficiency, familial hyperlipoproteinemia type I, familial lipoprotein lipase deficiency (disorder) [ambiguous], familial lipoprotein lipase deficiency with type I phenotype, high density lipoprotein cholesterol level QTL 11.