ASYMPTOMATIC HOMOZYGOUS HYPOBETALIPOPROTEINEMIA ASSOCIATED WITH APOLIPOPROTEIN B45.2

Familial hypobetalipoproteinemia is caused by apolipoprotein (ape) B g ene mutations and is frequently associated with a truncated apo-B prot ein in the plasma. Homozygosity for mutations yielding a truncated apo -B is extremely rare; fewer than five true homozygotes have been descr ibed in the world's literature. These patients typically have normal l evels of triglycerides and virtually absent low density lipoprotein (L DL) cholesterol. The clinical status of these patients is variable, ra nging from asymptomatic in two homozygotes who synthesized a truncated apo-B (apo-B87) to severe neurological disease resulting from vitamin E deficiency in a homozygote who synthesized a shorter apo-B (apo-B50 ). In this report, we describe a 48-year-old female homozygous for a n onsense mutation resulting in an even shorter apo-B, apo-B45.2. Althou gh this individual had virtually no LDL cholesterol, she was asymptoma tic and had normal plasma levels of vitamin E. This case demonstrates that homozygosity for an apo-B mutation associated with a relatively s hort apo-B truncation can be completely asymptomatic.