Definition
A diagnostic genetic test that makes use of fetal DNA circulating in the maternal blood to test the fetus for particular genetic variants.
Use in clinical context
Non-invasive prenatal diagnosis (NIPD) can be used when there is a known genetic condition in the family and the mother does not have the genetic variant for it. It works by testing for the variant in the blood sample taken from the mother and is not invasive to the pregnancy.
This type of testing is performed for:
- autosomal dominant conditions when the father is affected;
- conditions where there is an affected sibling, but the parents do not have the variant; and
- when both parents are carriers of different variants of an autosomal recessive condition, the father’s variant is tested for, if found to be present invasive testing may subsequently be performed to establish if the baby has also inherited the maternal variant
NIPD is also widely used for rhesus typing, and to determine to the sex of a fetus in families affected by serious X-linked conditions, such as Duchenne muscular dystrophy.
As part of the NHS Genomic Medicine Service, the national genomic test directory includes NIPD tests for a range of conditions including CAH, cystic fibrosis, Apert syndrome, Crouzon syndrome and several musculoskeletal conditions.
