How is Aicardi syndrome inherited?
Almost all of the reported cases of Aicardi syndrome have been sporadic or random meaning that they were not passed down from one generation to the next. New mutations are thought to be the cause of the condition. Parents of children with Aicardi syndrome are generally unaffected and other family members are not at increased risk.
Aicardi syndrome is classified as an X-linked dominant condition. While the gene associated with this disorder is not known, it is believed to be located on the X chromosome. In females (who have two X chromosomes), a mutation in one of the two copies of the gene in each cell is sufficient to cause the disorder. In males (who have only one X chromosome), a mutation in the only copy of the gene in each cell is nearly always lethal very early in development, so almost all babies with Aicardi syndrome are female. However, a few affected males with an extra copy of the X chromosome in each cell (47,XXY) have been identified. Males with a 47,XXY chromosome pattern also have a condition called Klinefelter syndrome.