Linkage of Chido and HL-A.

Of 156 families who were HL-A typed and Chido-typed, 15 were found to be suitable for linkage analysis. It was calculated that the odds in favour of linkage of Chido and HL-A are 1,450,000:1. The maximum likelihood estimate of the Chido:1.HL-A recombination fraction is 2½% with 95% confidence limits, obtained graphically, of 0 and 12%; the estimate of the Chido:2.HL-A recombination fraction is 1½%, with limits of 0 and 9%. Among Chido negative subjects, the antigens HL-A12 and W5 occurred more frequently than in a control population.