Inheritance of Fabry
We all inherit genes from our parents. These genes are contained in 46 chromosomes arranged in 23 pairs. One of these pairs determines whether an individual is male or female. Females have two x chromosomes and males have one x chromosome and one y chromosome. The x chromosome is inherited from the mother and the y chromosome is inherited from the father. In Fabry, the defective gene is located on the x chromosome. The disease, therefore, follows an x-linked inheritance pattern. X-linked recessive inheritance usually causes the disease to be expressed in males. However, in Fabry, both males and females can be affected. The inheritance pattern is called x-linked semi-dominant inheritance.
Women may have less severe disease manifestation than men but this is not always the case. The reason for this is that females have two x-chromosomes, one of which will be active and one inactive. It is a matter of chance which chromosome is active in a particular cell. If the pattern of activation is skewed in favour of the x-chromosome with the gene alteration, then a female is likely to have more severe symptoms.