Molecular diagnosis of hypobetalipoproteinemia: an ENID review.

Abstract Primary hypobetalipoproteinemia (HBL) includes a group of genetic disorders: abetalipoproteinemia (ABL) and chylomicron retention disease (CRD), with a recessive transmission, and familial hypobetalipoproteinemia (FHBL) with a co-dominant transmission. ABL and CRD are rare disorders due to mutations in the MTP and SARA2 genes, respectively. Heterozygous FHBL is much more frequent. FHBL subjects often have fatty liver and, less frequently, intestinal fat malabsorption. FHBL may be linked or not to the APOB gene. Most mutations in APOB gene cause the formation of truncated forms of apoB which may or may be not secreted into the plasma. Truncated apoBs with a size below that of apoB-3…

Clinical and biochemical characteristics of individuals with low cholesterol syndromes: A comparison between familial hypobetalipoproteinemia and familial combined hypolipidemia.

Background The most frequent monogenic causes of low plasma cholesterol are familial hypobetalipoproteinemia (FHBL1) because of truncating mutations in apolipoprotein B coding gene (APOB) and familial combined hypolipidemia (FHBL2) due to loss-of-function mutations in ANGPTL3 gene. Objective A direct comparison of lipid phenotypes of these 2 conditions has never been carried out. In addition, although an increased prevalence of liver steatosis in FHBL1 has been consistently reported, the hepatic consequences of FHBL2 are not well established. Methods We investigated 350 subjects, 67 heterozygous carriers of APOB mutations, 63 carriers of the p.S17* mutation in ANGPTL3 (57 heterozygotes and …

A Novel Loss of Function Mutation of PCSK9 Gene in White Subjects With Low-Plasma Low-Density Lipoprotein Cholesterol

Objectives— The PCSK9 gene, encoding a pro-protein convertase involved in posttranslational degradation of low-density lipoprotein receptor, has emerged as a key regulator of plasma low-density lipoprotein cholesterol. In African-Americans two nonsense mutations resulting in loss of function of PCSK9 are associated with a 30% to 40% reduction of plasma low-density lipoprotein cholesterol. The aim of this study was to assess whether loss of function mutations of PCSK9 were a cause of familial hypobetalipoproteinemia and a determinant of low-plasma low-density lipoprotein cholesterol in whites. Methods and Results— We sequenced PCSK9 gene in 18 familial hypobetalipoproteinemia subjects and i…

Corrigendum to "Molecular diagnosis of hypobetalipoproteinemia: An ENID review" [Atherosclerosis 195 (2) (2007) 19-27].

Mutations in MTP gene in abeta- and hypobeta-lipoproteinemia.

Abstract Familial hypobetalipoproteinemia (FHBL) and abetalipoproteinemia (ABL) are inherited disorders of apolipoprotein B (apo B)-containing lipoproteins that result from mutations in apo B and microsomal triglyceride transfer protein (MTP) genes, respectively. Here we report three patients with severe deficiency of plasma low-density lipoprotein (LDL) and apo B. Two of them (probands F.A. and P.E.) had clinical and biochemical phenotype consistent with ABL. Proband F.A. was homozygous for a minute deletion/insertion (c.1228delCCCinsT) in exon 9 of MTP gene predicted to cause a truncated MTP protein of 412 amino acids. Proband P. E. was heterozygous for a mutation in intron 9 (IVS9-1G>A),…