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Clinical scenario: a family affected by a genetic disease

Sonia Jamieson is 34 years old in the final trimester of her second pregnancy. Her first child Daniel presented with severe adrenal crisis
Sonia is a 34 year old woman who is in the final trimester of her second pregnancy. Her five-year-old son was diagnosed with congenital adrenal hyperplasia soon after his birth, and Sonia has been treated with dexamethasone since the first trimester of this pregnancy. Here are some notes from her obstetric and family history. Sonia is married to Adrian and she’s in her second pregnancy. Her son presented in the adrenal crisis as a new-born. Soon after this, he was diagnosed with congenital adrenal hyperplasia. Sonia and her husband were shown to be carriers for the causative mutation in the cytochrome p450 gene, and Daniel has two copies of the mutation.
Sonia knew that her next child could also be affected, and so, early in her current pregnancy, she had a simple, non-invasive genetic test to determine the sex of her unborn child. This just involved having a blood sample which was tested for circulating fetal DNA. The test is sensitive enough to reliably detect y-chromosome material. Sonya’s unborn child is a female, and because she’s still at risk of congenital adrenal hyperplasia, Sonya is being treated with dexamethasone to prevent female viralisation.
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This clinical case introduces genetic disease and non-invasive preimplantation test (NIPT).

The clinical scenario

Sonia Jamieson is 34 years old and is in the final trimester of her second pregnancy (G2, P1). Her first child Daniel was born in 2010 and presented with severe adrenal crisis. Sonia is anxious to prevent similar health problems for her next child. Genetic tests revealed that she and her husband carry a faulty gene variant (CYP21A2 deletions; see and that Daniel has 2 copies of this gene variant.
Sonia attends the obstetrics outpatient clinic and is under the care of a fetal medicine specialist. She had a non-invasive prenatal genetic test (NIPT) to determine the sex of her fetus because of a family history of Congenital Adrenal Hyperplasia (CAH). These tests showed that Sonia’s unborn child is a girl and she has been treated with dexamethasone since her pregnancy was confirmed. Sonia chose not to have subsequent chorionic villus sampling or amniocentesis to check the genotype of her unborn child.
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