Fabry

People probably carry from 5 to 10 genes with mutations in each of their cells. Genes are the unique set of instructions inside our bodies that make each of us an individual. They are the blueprint for our growth and development, as well as controlling how our bodies function. Genes are carried on structures called chromosomes and it is usual to have 23 pairs.

A child will inherit half of the chromosomes from the mother and the other half from the father resulting in 23 pairs. 22 of these pairs look the same in both males and females. Pair 23 are the sex chromosomes, and this is the pair that differ between females and males. The X chromosome is inherited from the mother and the Y chromosome is inherited from the father. More information about inheritance is available in our publication.

The inheritance pattern for Fabry is called X linked semi-dominant inheritance. Males only have one X chromosome, if it contains the faulty gene which cannot make enough enzyme alpha-GAL they are more likely to develop Fabry symptoms. Males can only pass the faulty gene to the daughters, so the daughters will be carriers of the disease, sons will not be affected by Fabry.

Females may have less severe Fabry symptoms than males but this is not always the case. This is because females have two X chromosomes, one of which will be active and one inactive. It is a matter of chance which chromosome is active or inactive in a particular cell. If the X chromosome with the faulty gene is active then a female is likely to show many of the classic features of Fabry. There is a 1 in 2 chance that that faulty gene will be passed on to the children, regardless of whether they are male or female.

All parents of children with Fabry can benefit from genetic counselling, the counsellor can provide advice on the risk to close relatives and to suggest whether the wider family should be informed. To find out during a pregnancy, if the baby is affected by Fabry, screening tests can be arranged early on during a pregnancy for those families who already have a child with Fabry. Where only one parent is a carrier, they can opt for carrier screening but it is not 100% reliable or accurate and is not possible in all cases. Amniocentesis and chorionic villus sampling are both available during the pregnancy to find out if the baby is affected by Fabry.

It is also possible to have Pre-implantation genetic diagnosis (PGD) screening to avoid passing Fabry to the baby. PGD is an assisted fertility treatment that involves checking the chromosomes of embryos before they are transferred in the womb using IVF techniques.