DMD carrier with heart failure has healthy pregnancy: Case study
Genetic counseling, prenatal testing can help parents make informed decisions
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A woman who developed heart failure due to Duchenne muscular dystrophy (DMD) was diagnosed and treated before she got pregnant, which led to a healthy outcome for her and her baby girl, according to researchers in Japan.
The woman’s case was reported in “Successful Pregnancy Outcome With Preconception Care in a Symptomatic Carrier of Duchenne Muscular Dystrophy: Case Report and Literature Review,” which was published in the American Journal of Medical Genetics. The researchers called for genetic counseling and prenatal testing to help parents make informed decisions before and during pregnancy.
DMD is a type of muscular dystrophy caused by a mutation in DMD, a gene in the X chromosome. In men, who have only one X chromosome, one mutated copy of the gene in each cell is sufficient to cause the disease, which results in progressive muscle weakness and wasting. Women with one mutated gene copy are called carriers. Women have two X chromosomes so they usually show little to no symptoms because the the X chromosome that carries the mutation is made inactive. They can still pass the disease to their offspring, however.
For some carriers, symptoms show up for the first time — or become worse — during pregnancy. Here, researchers described the case of a woman who began manifesting DMD symptoms before getting pregnant, allowing her to receive genetic counseling to understand what being a carrier could mean.
“Diagnosing DMD carrier status before pregnancy contributes to … shared decision making,” wrote the researchers, who claim “this is the first report of a DMD symptomatic carrier who was managed continuously from preconception through pregnancy for symptoms recognized before conception.”
Risk of complications in pregnancy
The woman had a history of irregular heartbeats and blood tests two years before she became pregnant showed high levels of creatine kinase, a sign of muscle tissue damage. Her ejection fraction, a measure of how much blood the heart’s left ventricle (lower chamber) pumps out with each heartbeat, indicated heart failure.
Genetic testing revealed a deletion of part of the DMD gene, indicating she was a carrier and that her symptoms were due to the disease. The woman had no family history of heart problems, suggesting a de novo mutation, meaning it wasn’t passed down from her parents.
The woman decided to postpone getting pregnant after her doctors warned her of the risk of complications from heart failure. She was started on bisoprolol and flecainide to increase her ejection fraction and restore the heart’s rhythm, and her cardiac condition improved. “Genetic counseling was provided concurrently with the treatment for heart failure,” the researchers wrote.
The woman became pregnant at age 31.
Despite being informed about prenatal testing, the family chose amniocentesis during her pregnancy to check for DMD in the baby. Amniocentesis involves removing a small sample of cells from the amniotic fluid that surrounds the baby in the womb. They planned to test for DMD later if the baby was a girl, but would have considered an abortion if it had been a boy.
The baby was a girl and “potentially a symptomatic carrier,” the researchers wrote. During the second trimester, the baby’s heart showed irregular beating, but improved as the pregnancy continued. The mother’s heart function remained stable and the baby’s heart function returned to normal after she was born.
“It was possible to provide treatment for heart failure and genetic counseling before pregnancy, leading to the successful delivery of a healthy baby without major complications,” the researchers wrote. “A carrier diagnosis will be considered after further genetic counseling as the child grows.”
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