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Testing the disease-causing gene for mutations that are common in a specific ethnic
group – X-linked diseases
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It is preferable to start by testing patients in the family, if there are any. If
the defects (mutations) are found using this method, it is possible:
- To allow a couple that has had an affected child to undergo prenatal diagnosis to
determine with a high degree of reliability whether subsequent fetuses (especially
male ones) are healthy or affected.
- To establish which females in the family carry the mutation and who are therefore
considered to be carriers but not affected. Women found to be carriers can undergo
prenatal tests in every pregnancy in order to establish whether or not the fetus
is affected.
If a patient cannot be examined:
Women in the family, preferably starting with those who are closely related to the
patient, such as the mother, (or male fetuses), may be tested directly for the presence
of the common mutations. However, the reliability of the test in such cases is reduced
depending on the percentage of patients with these mutations in the particular ethnic
group (degree of coverage or percentage of detection of the mutations tested).
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