Fisher and Race hypothesis Rh factor involves three different pairs of alleles located on three different closely linked loci on the chromosome pair. This system is more commonly in use today, and uses the 'Cde' nomenclature. C or c C or c D or d D or d E or e E or e Fig. .
Fischer and Race hypothesis In the above Fig. . , three pairs of Rh alleles (Cc, Dd and Ee) occur at different loci on homologous chromosome pair. The possible genotypes will be one C or c, one D or d, one E or e from each chromosome.
For e.g. CDE/ cde; CdE/cDe; cde/cde; CDe/CdE etc., All genotypes carrying a dominant ‘D’ allele will produce Rh positive phenotype and double recessive genotype ‘dd’ will give rise to Rh negative phenotype.