The distributions of N and F: measures of HLA haplotype concordance.

Nonrandom inheritance of the two HLA haplotypes of Chromosome 6, available from each parent among siblings affected by certain diseases, has afforded evidence of HLA-linked disease-susceptibility genes. Two algebraically equivalent measures of HLA haplotype concordance (that is, the excessive sharing of certain haplotypes among affected siblings) are used for family studies designed to test whether or not there is significant evidence of the existence of an HLA-linked disease-susceptibility gene or for inferring the mode of inheritance when this is already believed to apply. The distributions of these measures are derived under the null hypothesis of random inheritance of HLA haplotypes, and there is a short discussion of the case in which inheritance of a diseased gene causes a change, from the purely random case, in the distribution of haplotype concordance among affected siblings.