diagnosis of CdLS prenatally (before birth)

diagnosis of CdLS prenatally (before birth)


Can CdLS be diagnosed prenatally (before birth)?

There are several indicators that can lead to diagnosis of CdLS prenatally (before birth). Indicators may include parents with an earlier child with CdLS, or a new pregnancy in a family with a known genetic change in a gene associated with CdLS.

Another indicator may be no family history but features suggestive of CdLS on an ultrasound scan of an unborn baby.

Prenatal features suggestive of CdLS may include:

  • Intrauterine growth restriction (IUGR)
    IUGR is a condition in which a baby’s growth slows or stops during pregnancy. It is the most common suggestive feature of CdLS in a developing baby and typically begins in the second trimester (months 4 to 6) of pregnancy (50).
  • Prenatal limb differences
    E.g. Small hands and feet and/or missing portions or shortening of limbs.
  • Abnormal facial profile
    E.g. An undersized jaw (micrognathia) or protruding upper jaw (prominent maxilla) (51).
  • Increased nuchal thickness
    A collection of fluid under the skin at the back of a baby’s neck.
  • Diaphragmatic hernia
    A hole in the diaphragm, the muscles under the lungs that is responsible for breathing. The hole allows organs from the abdomen to move into the chest.
  • Cardiac malformation
    Heart defects (50).

If an ultrasound scan reveals features suggestive of a genetic disorder, a midwife or doctor will discuss the possible benefits and risks of prenatal genetic testing with the baby’s parents. The midwife or doctor will help parents to make a decision about the investigations that are available (R7).

If parents have a previous child with CdLS or there is a family member with a known change in a gene associated with CdLS, a midwife or doctor will discuss the possible benefits and risks of prenatal genetic testing.
Prenatal genetic testing can be carried out using DNA from samples of cells from the placenta (the organ linking the mother’s blood supply with the developing baby) or amniotic fluid (the fluid that surrounds the developing baby in the womb). Genetic testing can identify changes in any of the seven genes that are associated with CdLS (R8).

The tests can help parents make choices about further tests, care or treatment during the pregnancy or after the baby is born. It is important to remember that any prenatal test offered is optional. It is up to the family to decide whether any tests that are offered would be helpful or wanted.

The newest prenatal screening test, non-invasive cell-free foetal DNA (also called non-invasive prenatal screening or NIPS) can screen for various genetic changes in the developing baby in the mother’s blood. This might detect changes in genes that could cause CdLS. In families with a previous child with CdLS and a known mutation, this test may be a useful way to examine the specific gene that may be affected. However, in families without a previous child with CdLS, the result would be difficult or impossible to determine with accuracy, and would likely need extensive interpretation. Mosaicism also cannot be assessed using this testing method. This means this type of testing may not be useful for CdLS.

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