[Familial hypobetalipoproteinemia secondary to a mutation in the apolipoprotein B gene].

Familial hypobetalipoproteinemia (FHB) is a rare genetically heterogeneous disorder provoking abnormally low serum levels of apoprotein (apo) B, total cholesterol, and low-density lipoprotein (LDL-C). Patients carrying heterozygous mutations in the APOB (2p24) gene are usually asymptomatic, but homozygous mutations cause clinical disturbances as a result of intestinal fat malabsorption and fat-soluble vitamin deficiency. We present an asymptomatic boy, aged 8 years and 7 months, with low serum levels of apo-B, total cholesterol, triglyceride, LDL-C and very low-density lipoprotein (VLDL-C), as well as vitamin E deficiency. Three asymptomatic relatives also exhibited low apo-B, total cholesterol and LDL-C levels. The APOB (2p24) gene was fully sequenced, demonstrating a heterozygous mutation in exon 26 (G --> T) in all four members of this family. Familial genetic studies in FHB could be useful in the early detection and treatment of homozygous carriers.