How Fabry Disease is Inherited

The X chromosome tells the story

Since the genetic defect responsible for Fabry disease is located on the X chromosome, the way it gets passed down through families depends on whether the affected parent is male or female.

Affected fathers pass the altered gene to all of their daughters and none of their sons

  • Because men have one X and one Y chromosome, they can pass either one to their children.
  • If a man with Fabry disease passes his X chromosome (with the altered gene) to a child, the child will be a daughter (XX) - remember, the X and Y chromosomes determine whether a person is male or female - and the daughter will have the altered gene.
  • If he passes his Y chromosome to a child, the child will be a son (XY) and will not have Fabry disease.
  • Therefore, men with Fabry disease have a 100% chance of passing the altered gene to their daughters and a 0% chance of passing it to their sons. All the daughters and none of the sons of a man with Fabry disease have a chance of developing symptoms of Fabry disease.

Affected mothers can pass the altered gene to both their daughters and their sons

  • Because women have two X chromosomes, they always pass an X chromosome to their children.
  • A woman with Fabry disease has a 50% chance of passing the altered gene to each daughter and son.
  • If a woman with Fabry disease passes the X chromosome with the altered gene, her child (son or daughter) may develop symptoms of Fabry disease
  • If she passes along her normal X chromosome, her child (son or daughter) will not have Fabry disease.