Distribution of the GC (group-specific component) subtypes in cord bloods and blood donors.

The common allele, GC/1, was subtyped into GC*IF and GC*IS by isoelectric focusing, increasing the proportion of heterozygotes from 0.42 to 0.58. In a series of 200 blood donors and 200 cord bloods the allele frequencies were found to be: GC*IS = 0.59, GC*IF = 0.11, GC*2 = 0.30; and GC*IS = 0.54, GC*IF = 0.16, GC*2 = 0.30, respectively. These values were similar to frequencies obtained in studies of other Caucasian populations. The average probability of detecting non-paternity for this population is increased from 17% to 30% after subtyping GC 1.