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Genetics

22 May 2018

Medical first: Twins treated for rare condition while still in the womb

Doctors have managed to successfully correct a genetic disorder in twin boys, while they were still in the womb.

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Maarten and Linus were the first set of twins in the world to be treated, in utero, for a genetic disorder which could have resulted in a life-threatening condition – hyperthermia.

Mom of the twins, Corinna, already has a son who suffers from the genetic disorder, which was only discovered when he was two years old because he hadn't grown any teeth.

When she found out that she was pregnant again, with twins, her doctors confirmed that both twins had the genetic disorder.

The disorder is known as a genetic deficiency of ectodysplasin A (EDA), which causes X-linked hypohidrotic ectodermal dysplasia (XLHED). This results in irreversibly impaired development of the sweat glands.

The National Institutes of Health (NIH) describes hyperthermia as being "too hot for your health". It includes having abnormally high temperatures due to the failure of the heat-regulating mechanism in the body.

Regulating body temperature

If your body is unable to regulate temperature and you have an elevated temperature more often than not, it could result life-threatening conditions like heat exhaustion and heat stroke.

The corrective treatment was conducted by doctors and professors at University Hospital Erlangen, Germany, and was documented in the New England Journal of Medicine. The study abstract states that two pregnant women were treated – Corrina and the mother of a single baby.

Doctors treated the twins by administering the protein intra-amniotically at the 26th week and then again at the 31st week, which was two weeks before they were born.

Protein replacement therapy

CNN reports that doctors used a "fusion protein" or "protein-replacement therapy" which contained the fundamental part of the EDA protein. It is important that it be administered at the right time in the development of the foetus.

The doctors who had been investigating the treatment had been treating mice and dogs with an adaptation of the disorder by injecting a protein into the amniotic fluid. This is the first time that they had tried the treatment on human beings.

After confirmation of the pregnancy and the genetic disorder, Corinna contacted Dr Holm Schneider, who was conducting the study and treating mice and dogs.

The German mom told CNN that they realised that the treatment had worked after doing a "sweat test" – they found wet car seats during the first summer and were excited that the treatment had worked.

The, now, two-year-old twins have never become overheated and sweat "normally" like any other two-year-old toddlers and they have more teeth than their older brother, who suffers from the genetic disorder.

Critical factors need addressing

A few health professionals around the world weighed in on the result of the study and said that while the success story of the twins is remarkable, a larger clinical trial is still required.

Schneider said that they are hoping to embark on a larger study with 15 to 20 pregnancies for their follow up clinical trial.

Dr Susan Klugman, a professor of obstetrics and gynaecology at the Montefiore Medical Center in New York raised a few concerns about the dangers around diagnosis, reports CNN.

Klugman mentioned that injecting substances into the amniotic fluid may be harmful and have serious consequences, such as preterm birth or loss of the foetus.

"Timing is also crucial because doctors' ability to treat genetic disorder in the womb is limited by how and when a foetus is screened. Genetic disorders in particular are not often tested for in a prenatal screen, but some families might test for a specific disorder, if they know it runs in the family. Even then, it can take time to get results back, leaving little time to act," said Klugman.