Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (71 page)

   Familial hypertriglyceridemia is an autosomal dominant condition present in 1% of general population and 5% of survivors of AMI < 60 years of age. The distinction from familial combined hyperlipidemia is made only by extensive family screening.

   There is elevated TG (usually 200–500 mg/dL) and VLDL with normal LDL-C and decreased HDL-C.

ABETALIPOPROTEINEMIA (BASSEN-KORNZWEIG SYNDROME)

   Definition

   Abetalipoproteinemia is a rare autosomal recessive disorder in which the liver and intestine cannot secrete apo B.

   It should be ruled out in children with fat malabsorption, steatorrhea, failure to thrive, neurologic symptoms, pigmented retinopathy, and/or acanthocytosis.

   Laboratory Findings

   Hematology

   Abnormal RBCs (acanthocytes) are present in the PBS; may be 50–90% of RBCs and are characteristic. Decreased RBC life span may vary from severe hemolytic anemia to mild compensated anemia. Abnormal pattern of RBC phospholipids.

   ESR is markedly decreased (e.g., 1 mm/hour).

   Core laboratory

   Marked decrease in serum TG (<30 mg/dL) with little increase after ingestion of fat, and in TC (20–50 mg/dL). Chylomicrons, LDL-C, VLDL, apo B-48, and apo B-100 are absent; HDL-C may be lower than in normal persons.

   Low serum carotene levels.

   A variant is normotriglyceridemic abetalipoproteinemia in which patient can secrete apo B-48 but not apo B-100, resulting in normal postprandial TG values but marked hypocholesterolemia; associated with mental retardation and vitamin E deficiency.