Doctors have successfully treated a genetic condition in an unborn fetus

Pregnancy can be a time of intense emotions for everyone involved. Just revisit knocked up, Judd Apatow’s 2007 romantic comedy, as an example. Seeing that little line on an at-home test or having your first ultrasound can be among the happiest and most stressful times in a person’s life. It can also be one of the scariest, especially if you find out that your unborn child is suffering from a fatal disease.

This was the situation of two parents from Ottawa. Twice before, they had had children who died young – one at two years old and the other at 8 months old – from a rare genetic condition known as Infantile-Onset Pompe. Now they had another child on the way and a recent diagnosis that he also had Pompe. They were looking at another tragedy unless someone could step in to save the day. That person was Dr. Tippi MacKenzie, a pediatric surgeon at the University of California, San Francisco.

Dr. MacKenzie had previously treated fetuses with a hemoglobin disorder by giving them blood transfusions through the umbilical cord. The success of this practice led her to think that a similar method could be used to treat fetal enzyme disorders. After the success of using the method in rats, the FDA suggested that Dr. MacKenzie begin a clinical trial in humans, targeting fetuses with enzyme disorders who had approved enzyme treatments.

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Due to the family history, two previous children with Pump, they knew to seek him out and were listed for trial. The results of this trial were recently published in The New England Journal of Medicine. The baby was born healthy and is around 16 months old at the time of this writing. Her parents named her Ayla and she is developing normally, seemingly unperturbed by the enzyme disorder that could have sent her down a very different path.

To understand how doctors pulled off a biological antics to save a life, we first need to talk about Infantile Onset Pompe. It affects less than 1 in 100,000 babies, although it has obviously given this particular family more than its fair share. People with Pompe have low levels of certain enzymes, if they have measurable levels, which leads to a buildup of a type of sugar called glycogen. The result is weakened muscles and an enlarged heart, which can stunt development and ultimately lead to death.

In cases of Pompe that appear after birth, doctors can treat patients by providing them with the missing enzymes. It won’t undo damage that has already happened, but it can prevent things from getting worse. But when it strikes early, before a person is even born, the disease tears muscle fibers and thickens the heart before anyone knows there is a problem. In the case of Pompe and other lysosomal storage diseases, early diagnosis and treatment are crucial.

With this in mind, doctors decided to try enzyme replacement therapy while the fetus is still in the womb, in an effort to prevent the disease from causing harm. When Ayla’s mother was 24 weeks pregnant, they received their first dose of the enzyme, delivered directly to Ayla through the umbilical cord. Ayla and her mother received six doses in total, each spaced two weeks apart.

By all accounts, the treatment seems to have worked. Ayla was born without the characteristic heart problems associated with other Pump babies, and she had no delays in motor development that can be attributed to muscle damage.

Meanwhile, Ayla and her mother weren’t the only participants in the trial. At the time of publication, two more fetuses had been treated with this method and doctors reported that another of the babies was born on October 27 following prenatal treatment for Hunter syndrome. Doctors are monitoring his condition, according to The New York Times.

Admittedly, the sample size is small and it will take years to see how the treatment will perform in the long term. But if it works, and it looks like it has so far, it could be a breakthrough for a collection of debilitating or life-threatening disorders.