GM AND KM IMMUNOGLOBULIN ALLOTYPES IN A SPANISH PYRENEAN POPULATION -VAL DARAN

Four hundred and thirteen unrelated individuals (202 autochthonous and 211 non-autochthonous) of Val d'Aran (Catalan Pyrenees) have been ana lysed for the GM and KM immunoglobulin genetic system using the inhibi tion haemagglutination method. This population was defined by eight GM haplotypes (GM3 23 5*, GM83 5*, GM*1, 17 21, 28, GM*1, 2, 17 21, 28, GM1, 17 5*, GM*1, 17 5, 6, 11, 24, GM*1, 17 10, 11, 13, 15 and GM*1, 17 10, 11, 13, 15, 16) inferred from the 17 observed phenotypes. The Val d'Aran population frequencies conform to Hardy-Weinberg expectatio ns. The frequencies of phenotypes and haplotypes show a definite homog eneity between the autochthonous and non-autochthonous people of Val d 'Aran and 11 other Pyrenean populations (Mauli on, Macaye, St. Jean Pi ed de Port, Vallee de L'Ouzom, Gavarnie, Bari,ges, Luz St. Sauveur, Es parros, Camurac, Capcir and Pays de Sault) that have already been stud ied for the same allotypes. A factorial correspondence analysis was pe rformed for the 12 autochthonous Pyrenean populations, showing a high frequency of the GM3 23 5* haplotype in the three Pyrenean regions (W estern, Central and Eastern), while the GM1,17 21,28 haplotype is mai nly found in the Central region, GM3 5* in the Eastern and Western zo nes, and the GM1,2,17 21,28 is mainly present in the Central and East ern populations. The results show a relative regional homogeneity, so there is no evidence of a frequency gradient in the Pyrenean populatio ns for the GM and KM genetic systems. It may, however, be noticed that the Central Pyrenean populations form a group, with one population (V allee de l'Ouzom) isolated from the rest, probably because of its part icular model of inheritance by which the heritage is passed to the fir st born without sex consideration. It has been possible to point out s ome differences in the genetic structure of the autochthonous and non- autochthonous Val d'Aran population and to place the autochthonous Ara nese group among its Pyrenean neighbours.