title: A tale of 2 cousins: An atypical and a typical case of abetalipoproteinemia.
abstract: Abetalipoproteinemia (ABL) is a rare recessive genetic disease caused by mutations of the MTTP gene. This disease is characterised by a defect in the lipidation of APO B and the absence of VLDL and chylomicron production. Patients affected by ABL present neurological, hemalogical and gastro-intestinal symptoms due to deficiency in lipophilic vitamins and fat malabsorption. We herein report the case of two cousins, one presenting classical symptoms of abetalipoproteinemia and one presenting a much attenuated phenotype. The proband carried a novel combination of MTTP mutations, the 1867+1G>A and the R540C mutations. This patient never received any vitamin supplements and was relatively free of symptoms despite an undetectable APO B concentration. Her cousin was homozygous for 1867+1G>A MTTP mutation and presented most of the classical symptoms of ABL. In conclusion we report a very unusual kindred where on affected member is strongly symptomatic of ABL whereas the other presents very mostly asymptomatic disease suggesting that ABL can present itself with a very incomplete clinical penetrance.
authors: Nutrition, Metabolism and Atherosclerosis Clinic, Institut de Recherches Cliniques de Montréal, Québec, Canada.
authors: Martine
authors: M
authors: Paquette
authors: Nutrition, Metabolism and Atherosclerosis Clinic, Institut de Recherches Cliniques de Montréal, Québec, Canada; Department of Nutrition, Université de Montréal, Québec, Canada.
authors: Robert
authors: R
authors: Dufour
authors: Department of Medicine, University of Western Ontario, Robarts Research Institute, Ontario, Canada.
authors: Robert A
authors: RA
authors: Hegele
authors: Nutrition, Metabolism and Atherosclerosis Clinic, Institut de Recherches Cliniques de Montréal, Québec, Canada; Division of Experimental Medicine, Department of Medicine, McGill University, Québec, Canada. Electronic address: alexis.baass@ircm.qc.ca.
authors: Alexis
authors: A
authors: Baass
mesh_terms: D000012:Abetalipoproteinemia / Q000235:genetics* / Q000378:metabolism; D000328:Adult; D002352:Carrier Proteins / Q000235:genetics; D005260:Female; D006801:Humans; D008297:Male; D009154:Mutation; D010375:Pedigree; D010641:Phenotype; D055815:Young Adult
chemical_list: D002352:Carrier Proteins; C106092:microsomal triglyceride transfer protein
keywords: Abetalipoproteinemia; Apo B; Low-density lipoprotein; MTTP; Vitamin A; Vitamin E