recessive

describing a gene (or its corresponding characteristic) whose effect is shown in the individual only when its ALLELE is the same, i.e. when two such alleles are present (the double recessive condition). Many hereditary diseases (including cystic fibrosis) are due to the presence of a defective gene as a double recessive. They are said to show autosomal recessive inheritance, since the gene is carried on an autosome (any chromosome other than a sex chromosome). - recessive n.