Barth Syndrome Foundation Inc

Barth syndrome (BTHS) is an X-linked genetic condition, usually transmitted from mother to son (although there is a relatively high incidence of new mutations in Barth syndrome and one confirmed case report of a female Barth syndrome patient). A mother who is a carrier of a Barth syndrome mutation (the gene is named tafazzin — also called TAZ or G4.5) shows no signs or symptoms of this disorder herself, probably due to skewed X-chromosome inactivation.

There is a 50% chance that a boy born to a female carrier will have Barth syndrome, whereas girls born to a carrier have a 50% risk of being carriers themselves. All daughters of a male with Barth syndrome will be carriers, however no sons will be affected. Because there are proven non-carrier mothers, all mothers of Barth syndrome children should be tested in order to define the genetic risk in each family.

Any male child related through the female line to a Barth syndrome individual should be tested for the disorder, as there can be great variation in phenotype even among affected siblings.

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