you inherit two mutated genes, one from each parent. These disorders are usually passed on by two carriers. Their health is rarely affected, but they have one mutated gene (recessive gene) and one normal gene (dominant gene) for the condition. recessive single-gene diseases often show a clear pattern in which the disease "skips" one or more generations. Phenylketonuria (PKU) is a prominent example of a single-gene disease with an autosomal recessive inheritance pattern.
