STRONG LINKAGE DISEQUILIBRIUM BETWEEN HLA-CW*0706 AND HLA-B*44032 IN THE BUBI POPULATION FROM EQUATORIAL GUINEA
Saskia van der Vlies, Christina EM Voorter, Rosario de Pablo, Carlos Vilches and Ella M van den Berg-Loonen. Tissue Typing Laboratory, University Hospital Maastricht, Maastricht, The Netherlands. 

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The Bubi are a population living on the Island of Bioko. They were studied for their HLA distribution and possible linkage between HLA and parasitic infections. 100 Unrelated Bubi's were typed by serology and PCR-SSP for HLA-A, -B and -C. Cw*02, Cw*04, Cw*0602, Cw*07, Cw*1601 and Cw*17 were found frequently and were associated with B*1503, B*53, B*58, B*44, B*45 and B*42, respectively. Since the recently described allele Cw*0706 was detected in a Bubi individual and was associated with B44, we studied the HLA subtypes of the B- and C-alleles of the B*44-Cw*07 positive individuals of the Bubi population (n=20). HLA-B was typed by SBT of exons 2 and 3 and for HLA-C exons 1, 2, 3 and 5 were included. Sequencing of exon 1 was necessary to distinguish the alleles Cw*1701/02 and exon 5 for distinction of Cw*1801/02 and Cw*0701/06. All 20 individuals typed Cw*0706 positive, 19 of which carried the B*44032 allele. The individual from which the allele Cw*0706 (X97321) was originally derived, was typed B*4407 positive. An association between Cw*0706 and B*4407 was suggested at the time, but in this study the linkage between Cw*0706 and B*44032 proved much more pronounced. The HLA-C subtype was also determined in 19 B44 negative Cw7 positive Bubi's. None of them typed Cw*0706 positive. To determine whether the linkage between Cw*0706 and B*44032 was limited to the Bubi population, we typed 9 Dutch families in which B44 and Cw7 segregated on one haplotype. None of the individuals showed the presence of Cw*0706 nor B*44032.