| − | A '''Genetic disease carrier''' is an individual who possesses one copy of a mutant [[allele]] that causes a disease only when two copies are present. Although carriers not affected by the disease, two carriers can produce a child who has the disease. | + | A '''Genetic disease carrier''' is an individual who possesses one copy of a mutant [[allele]] that causes a disease only when two copies are present. Although carriers not affected by the disease unless the gene is codominant with the "normal" gene, two carriers can produce a child who has the disease. |