Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (68 page)

   It occurs in 1 in 20 adults with mildly increased TC levels (240–300 mg/dL) secondary to increased HDL-C (>70 mg/dL). LDL-C is not increased, and TG is normal.

SEVERE HYPERTRIGLYCERIDEMIA (TYPE I) (FAMILIAL HYPERCHYLOMICRONEMIA SYNDROME)

   Definition

   Hypertriglyceridemia is a rare autosomal recessive trait due to deficiency of lipoprotein lipase (LPL) or apo C-II or circulating inhibitor of LPL.

   There is marked heterogeneity in causative molecular defects.

   Laboratory Findings

   Core laboratory: changes due to fatty liver (increased serum transaminase)

   Persistent very high TG (>1,000 mg/dL) with marked increase in VLDL and chylomicrons.

   Deficiency of apo C-II is shown by isoelectric focusing or two-dimensional gel electrophoresis of plasma.

FAMILIAL HYPERCHOLESTEROLEMIA (TYPE II)

   Definition

   Familial hypercholesterolemia is inherited as an autosomal dominant disorder. Homozygous patients are very rare (1 per million).

   Clinical manifestations include increased TC (xanthomata, corneal arcus, CAD that causes death usually before age 30 years). Heterozygous patients present with premature CAD; tendinous xanthomas and corneal arcus are often present.

   Laboratory Findings

   Homozygous