Question

If the alleles for the Rh factor are represented as D (for positive) and d (for negative), and anindividual has an Rh+ blood type, what is their possible genotype(s)?

Answer 1

The D allele represents a dominant allele, so whenever it is present in an individual, he/she will have Rh+. Because of this, for an individual to be Rh- it must necessarily have two "dd" alleles. Therefore, the possible genotypes for an Rh+ individual are DD and Dd.