In the early stages of choroideremia, the choroid and the retinal pigment epithelium initially deteriorate. Eventually, photoreceptor cells also degenerate. As a result, vision is lost. Inheritance Choroideremia is genetically passed through families by an X-linked pattern of inheritance. In this type of inheritance, the gene for the disease is located on the X chromosome.
Females have two X chromosomes, only one of which generally carries the disease gene.
Because they have a healthy version of the gene on their other X chromosome, females ordinarily are not affected by X-linked diseases such as choroideremia. Males cannot be carriers of X-linked diseases. Males affected with an X-linked disease always pass the gene on the X chromosome to their daughters, who then become carriers. Affected males never pass an X-linked disease gene to their sons because fathers pass the Y chromosome to their sons. Treatment Scientists discovered the exact location of the choroideremia gene on the X chromosome in the early 1990's.