A “recessive gene” is the gene that is the less likely to manifest a trait in an allelic combination. For example, if there are two genes that determine a particular trait, and one is a “dominant gene” and the other is a “recessive gene,” the trait with the dominant gene is more likely to appear and the trait with the recessive gene is less likely to appear.Only when both genes are recessive will the trait be expressed.
Using the ABO blood type as an example, the type O gene is recessive to the type A and B genes, so you must inherit the type O gene from both parents to be type O.
Note that the expression “recessive” does not mean “inferior nature,” but simply refers to the fact that the trait is difficult to manifest. Therefore, to avoid misunderstanding, it is recommended to refer to “recessive genes” as “occult genes.”
Phenylketonuria is an example of a disease caused by a recessive gene. This disease is caused by a weak enzyme that breaks down the amino acid phenylalanine, which results in a buildup of phenylalanine in the body and can affect mental development.
