Discriminating between allelic and interlocus differences among human immunoglobulin VH4 sequences by analyzing single spermatozoa.

To address the challenging issue of distinguishing allelic and interlocus differences among repetitive sequences, human immunoglobulin VH4 loci in the parental haplotypes of 13 donors were determined by analyzing single spermatozoa. VH4 sequences detected among these donors were assigned to their corresponding loci based on the fact that allelic sequences usually segregate into different gametes. Four out of the ten VH4 loci were shown to contain null alleles that are undetectable with diploid materials. The distribution of the allelic variation within the analyzed regions at the VH4 loci is highly biased.