A woman who is a carrier for Fabry disease has children with a man who does not have the disorder. Their son has the disease, and their daughter also has somesymptomsof Fabry disease even though she could only have inherited one affected allele. What is the explanation for the daughter having some symptoms of Fabry disease?

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Quizplus · Accepted Answer

Although the girl may be seeking attention, she can have real symptoms of Fabry disease. In order to prevent a "double dose" of alleles on the X chromosome, one X chromosome in all somatic cells of a female is inactivated. Although Fabry disease is much more common among males, female carriers may have significant symptoms of the disorder as a result of skewed X-chromosome inactivation in different tissues, which results in greater expression of the maternal X (with the mutated allele) than the paternal X (with the normal allele). It is possible that the son's father is not the daughter's father, but the more likely explanation is the presence of greater inactivation of the father's X chromosome than the mother's X chromosome. A somatic mutation does not affect the expression of this enzyme.

A Woman Who Is a Carrier for Fabry Disease Has