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:
If a patient cannot be examined:
Family members, or a fetus, may be directly tested 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). In such
cases, it is recommended that partners of family members found to be carriers also
undergo tests for carrier status.
- 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 are healthy
- To establish which family members carry the mutation and are therefore considered
to be carriers but not affected. Family members found to be carriers will be at
risk for having an affected child if their partners are also carriers, and therefore
their partners should also undergo testing for carrier status.