Dominance in
genetics is a relationship between
alleles of one
gene, in which the effect on
phenotype of one allele masks the contribution of a second allele at the same
locus. The first allele is
dominant and the second allele is
recessive. For genes on an
autosome (any
chromosome other than a
sex chromosome), the alleles and their associated traits are
autosomal dominant or
autosomal recessive. Dominance is a key concept in
Mendelian inheritance and
classical genetics. Often the dominant allele codes for a functional
protein whereas the recessive allele does not.