Recessive Health Dictionary

A term used in genetics to describe one of the ways by which a gene is passed from parent to offspring. Many characteristics are determined by a single pair of genes, 1 of each pair being inherited from each parent. A recessive gene is overridden by an equivalent dominant gene. For example, the gene for blue eye colour is recessive; therefore, if a child inherits the gene for brown eyes from 1 parent and the gene for blue eyes from the other, the “blue eye” gene is overridden by the “brown eye” gene, and the child has brown eyes. The child must inherit the recessive blue eye gene from both parents in order to have blue eyes. Many genetic disorders are determined by a recessive gene. Examples include cystic fibrosis and sickle cell anaemia. The child will only have the disease if he or she inherits the gene from both parents.

Tending to recede. In genetic terms, a recessive gene is one whose expression remains dormant if paired with an unlike allele. The trait will only be manifest in an individual homozygous for the recessive gene. (See GENES.)

adj. 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). Compare dominant. —recessive n.