![]() ![]() Although these disorders can affect both males and females, only females can pass variants in mitochondrial DNA to their children. Disorders with mitochondrial inheritance result from variants in mitochondrial DNA. Mitochondrial inheritance: Mitochondria, which are the energy-producing centers inside cells, each contain a small amount of DNA. The chance of developing a genetic condition with codominant inheritance, and the characteristic features of that condition, depend on which versions of the gene are passed from parents to their child. All sons of a man with a Y-linked disorder will inherit the condition from their father.Ĭodominant inheritance: In codominant inheritance, each parent contributes a different version of a particular gene, and both versions influence the resulting genetic trait. Y-linked inheritance: Because only males have a Y chromosome, only males can be affected by and pass on Y-linked disorders. An affected daughter may have milder signs and symptoms than an affected son. Therefore, with each pregnancy, a woman with an X-linked disorder has a 50 percent chance of having a child with the altered gene. A woman passes on one or the other of her X chromosomes to each child. The sons of a man with an X-linked disorder will not be affected, but all of his daughters will inherit the altered gene and may develop signs and symptoms of the condition. X-linked: Because the inheritance pattern of many X-linked disorders is not clearly dominant or recessive, some experts suggest that conditions be considered X-linked rather than X-linked dominant or X-linked recessive.Īs above, the probability of passing on an X-linked disorder differs between men and women. Females with one gene variant associated with an X-linked recessive disorder typically have no or very mild signs or symptoms of the condition. With each pregnancy, a woman who carries an altered gene for X-linked recessive has a 50 percent chance of having sons who are affected and a 50 percent chance of having daughters who carry one copy of the altered gene. The sons of a man with an X-linked recessive disorder will not be affected, and his daughters will carry one copy of the altered gene. X-linked recessive inheritance: Because of the difference in sex chromosomes, the probability of passing on an X-linked recessive disorder also differs between men and women. Therefore, a woman with an X-linked dominant disorder has a 50 percent chance of having an affected daughter or son with each pregnancy. Therefore, the sons of a man with an X-linked dominant disorder will not be affected, but all of his daughters will inherit the condition. A man passes on his Y chromosome to all of his sons and his X chromosome to all of his daughters. X-linked dominant inheritance: The chance of passing on an X-linked dominant condition differs between men and women because men have one X chromosome and one Y chromosome, while women have two X chromosomes. If only one parent is a carrier of the altered gene and the other parent does not carry the variant, none of their children will develop the condition, and the chance with each pregnancy of having an unaffected child who is a carrier is 50 percent. The chance with each pregnancy of having an unaffected child who is a carrier of the disorder is 50 percent, and the chance that a child will not have the disorder and will not be a carrier is 25 percent. In these cases, the child's parents are unaffected, but the child may pass on the condition to his or her own children.Īutosomal recessive inheritance: Two unaffected people who each carry one copy of the altered gene for an autosomal recessive disorder (carriers) have a 25 percent chance with each pregnancy of having a child affected by the disorder. However, in some cases an autosomal dominant disorder results from a new (de novo) variant that occurs during the formation of egg or sperm cells or early in embryonic development. The chance that a child will not inherit the altered gene is also 50 percent. For example:Īutosomal dominant inheritance: A person affected by an autosomal dominant disorder has a 50 percent chance of passing the altered gene to each child. One important factor is how the condition is inherited. This can be difficult to predict in some cases because many factors influence a person's chances of developing a genetic condition. When a genetic disorder is diagnosed in a family, family members often want to know the likelihood that they or their children will develop the condition. ![]()
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