AAADMJ – Associação Atlântica de Apoio aos Doentes de Machado-Joseph

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Genetic Testing for DMJ

DMJ is hereditary in nature and the transmission of the disease follows what geneticists call a ‘dominant pattern’. This means that patients usually carry one copy of the disorder and that this copy is sufficient, if passed on to a child, for the disease to manifest. The identification of chromosome 14 as the chromosome where the gene responsible for DMJ is found (called ATXN3), as well as knowledge of the gene itself, discoveries that took place between 1993 and 1994, have made it possible to offer families with DMJ various types of genetic testing:

Diagnostic test:

Test carried out on a person with alterations compatible with DMJ and usually with a family history of the disease, to confirm the diagnosis of DMJ, made by a Neurologist.

Predictive Testing:

A test that involves a system of consultations (neurology, medical genetics, psychology) in which a person ‘at risk’ for DMJ (i.e. who has a direct relative, father or mother, with the disease) will have their molecular analysis done to find out whether or not they have the alteration (mutation).

Prenatal testing:

Test carried out during pregnancy, allowing couples in which one of the people carries the mutation to find out if the foetus also has the alteration.

Pre-implantation genetic testing:

A test that detects a genetic alteration in the embryo before it is implanted in the uterus, so that the baby is born without the alteration. This test is carried out in the context of in vitro fertilisation/embryo biopsy.

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