A person with one recessive gene doesn't have the trait but is a carrier of the trait and can pass the gene on to his children. If an abnormal X-linked gene is dominant, affected males transmit the abnormality to all of their daughters but none of their sons. The sons of the affected male receive his Y chromosome, which doesn't carry the abnormal gene. Affected females with only one abnormal gene transmit the abnormality to half their children, male or female. If an abnormal X-linked gene is recessive, nearly everyone with the trait is male.
Men transmit the abnormal gene only to their daughters, all of whom become carriers.
Carrier mothers do not have the trait but transmit the gene to half their sons, who usually have the trait. None of their daughters have the trait, but half are carriers. It never comes from the father, who instead supplies the Y chromosome. In codominant inheritance, both genes are expressed. Abnormal Mitochondrial Genes Inside every cell are mitochondria, tiny structures that provide the cell with energy.