Is Swyer syndrome inherited ?
Most cases of Swyer syndrome are not inherited; they occur in people with no history of the condition in their family. These cases result either from nongenetic causes or from new (de novo) mutations in a gene that occur during the formation of reproductive cells (eggs or sperm) or in early embryonic development.  SRY-related Swyer syndrome is usually caused by a new mutation. However, some individuals with Swyer syndrome inherit an altered SRY gene from an unaffected father who is mosaic for the mutation. Mosaic means that an individual has the mutation in some cells (including some reproductive cells) but not in others. In rare cases, a father may carry the mutation in every cell of the body but also has other genetic variations that prevent him from being affected by the condition. Because the SRY gene is on the Y chromosome, Swyer syndrome caused by SRY gene mutations is described as having a Y-linked inheritance pattern.  When Swyer syndrome is associated with an MAP3K1 or NR5A1 gene mutation, the condition is also usually caused by a new mutation. In the rare inherited cases, the mutation may be inherited from either parent, since these genes are not on the Y chromosome. In these cases, the condition has an autosomal dominant pattern of inheritance, which means one copy of the altered gene in each cell is sufficient to cause the condition.  Swyer syndrome caused by mutations in the DHH gene is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition are carriers of one copy of the altered gene. Female carriers of a DHH gene mutation generally have typical sex development. Male carriers of a DHH gene mutation may also be unaffected, or they may have genital differences such as the urethra opening on the underside of the penis (hypospadias).