Volume 8, Issue 1, Page 33

European Journal of Human Genetics

January 2000, Volume 8, Issue 1, Pages 33 – 41

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Article

A linkage disequilibrium map of the MHC region based on the analysis of 14 loci haplotypes in 50 French families
Alicia Sanchez-Mazas^1,2, Sami Djoulah³, Marc Busson³, Isabelle Le Monnier de Gouville³, Jean-Claude Poirier³, Catherine Dehay³, Dominique Charron³, Laurent Excoffier^1,2, Stefan Schneider^1,2, André Langaney^1,2, Jean Dausset⁴ & Jacques Hors³
¹Laboratory of Genetics and Biometry, Department of Anthropology and Ecology, University of Geneva, Switzerland     ²Musée de l’Homme, Paris, France     ³LNH, Department of Immunology and INSERM U396, Saint-Louis Hospital, Paris, France     ⁴CEPH, Fondation Jean Dausset, Saint-Louis Hospital, Paris, France

Correspondence to: A Sanchez-Mazas , Laboratory of Genetics and Biometry, Department of Anthropology and Ecology, University of Geneva, 12 rue Gustave-Revilliod, CH-1227 Carouge, Geneva, Switzerland. Tel: +41 22 702 69 84; Fax: +41 22 300 03 51; E-mail: sanchez@sc2a.unige.ch.

Keywords

MHC;   linkage disequilibrium;   HLA haplotypes;   French population;   CEPH families;   population genetics

Abstract

A sample of 100 individuals from 50 French families of known pedigrees were typed for 14 loci of the HLA region (DPB1, DQB1, DQA1, DRB1, DRB3, 4, 5, C4B, C4A, Bf, C2, TNFa, TNFb, B, Cw, A). Linkage disequilibrium in each pair of loci was investigated by an exact test using a Markov chain algorithm. The results indicate no disequilibrium between DPB1 and the other loci, whereas the other class II genes are all significantly linked to each other. Linkage disequilibrium is also detected between some pairs of class I and class II-class I loci despite the long physical distance separating the loci (eg A-B, Cw-DRB1). On the other hand, some contiguous loci of the class III region are found to be in equilibrium with each other. Several hypotheses including selection, but also unequal allelic diversity at different MHC loci are discussed to explain this complex pattern of linkage disequilibrium. European Journal of Human Genetics (2000) 8, 33-41.

Received 3 February 1999; Revised 23 June 1999; Accepted 3 August 1999