<unk>  is caused by a mutation occurring in the<unk> q13.1 locus of the<unk> -chromosome. Most often, this disease affects males whose mother is a carrier (heterozygous) for the disorder. Because females have two<unk> -chromosomes, the mother will not be affected by carrying only one abnormal<unk> -chromosome, but any male children will have a 50% chance of being affected with the disorder by inheriting the faulty gene. Likewise, her female children will have a 50% chance of being carriers for the immunodeficiency.<unk>  can also arise through de novo mutations and can be prevented in females by<unk> -inactivation. In<unk> -inactivation the preferential selection of the non-mutant<unk>  chromosome during development results in the outcome that none of the mature female cells actively express the<unk>  mutation, they are immunologically unaffected and have no carrier burden. A de novo mutation is an alteration in a gene caused by the result of a mutation in a germ cell (egg or sperm) or in the fertilized egg itself, rather than having been inherited from a carrier. Since only 1/3 of all<unk>  patients have a positive family history of<unk> , it is hypothesized that de novo mutations account for a significant percentage of cases.<unk> -inactivation occurs in a completely random manner, in females, very early in embryonic development. Once an<unk>  is inactivated, it remains inactivated throughout the life of that cell and any of its daughter cells. It is important to note that<unk> -inactivation is reversed in female germline cells, so that all new oocytes receive an active<unk> . Regardless of which<unk>  is inactivated in her somatic cells, a female will have a 50% chance of passing on the disease to any male children.
X-linked severe combined immunodeficiency
Severe combined immunodeficiency
Common variable immunodeficiency
X-linked agammaglobulinemia
Combined immunodeficiencies
Adult-onset immunodeficiency syndrome
Primary immunodeficiency
Chronic granulomatous disease