Montreal Gazette

MUHC researcher­s pinpoint cause of molar pregnancie­s

- AARON DERFEL

Isabelle Lafond will never forget the day she was told that even though she was pregnant, she wasn’t carrying a fetus. “It was horrible, like a death,” she recalled of that day two years ago. “I didn’t understand what was happening, what the problem was, why me. Today, it’s still hard to accept.” Lafond, who is 27, has had two complete molar pregnancie­s. Instead of a fetus growing inside the uterus, a mole grows inside, and in up to 15 per cent of cases, that mole turns malignant and can cause cancer. Now scientists at the Research Institute of the McGill University Health Centre have discovered three genetic mutations that are likely to cause a recurrent type of molar pregnancy. The discovery paves the way for better genetic screening, says the lead researcher of a study just published in the American Journal of Human Genetics. “We’re now in a better position to provide accurate genetic counsellin­g,” said Rima Slim, a geneticist at the MUHC’s research institute. “This is precision medicine,” Slim added. “We can test patients who have recurrent molar pregnancie­s of this type, and if they have mutations in any of the three genes, we can advise them based on the exact defects.”

Every year in Quebec, about a hundred women learn that they have either a partial or complete molar pregnancy. In a complete molar pregnancy — the kind Lafond experience­d — no fetus develops at all and the placental tissue grows into an abnormal mass. In up to 15 per cent of such cases, that mass is malignant and requires chemothera­py following curettage. (By comparison, during a partial molar pregnancy an incomplete embryo and an abnormal placenta may start to form.) In Lafond’s case, she tried to have another baby two years later. There was reason to be confident since the Mirabel resident had given birth to a healthy girl, Raphaëlle Deshaies, on June 6, 2015. But in August 2017, a sonogram revealed another complete molar pregnancy. Lafond was devastated. “What people have to understand is that I was pregnant both of those times,” she explained. “But in the end, we didn’t have a child. For my husband and I, it was like losing a child two times.” “Often I will hear people say, ‘But you already have a child who is healthy,’ ” Lafond continued. “I know I’m fortunate because there are women who can’t have children at all, at all, at all. But I have the desire to have more children. ” Lafond was among 68 patients who had their genomes sequenced, leading to the discovery of the three genes with mutations. Slim and her colleagues took their research a step further, reproducin­g one of the genetic defects in a lab mouse. To their surprise, they ended up solving a 40-year-old scientific mystery. There is a type of molar pregnancy — the scientific name is androgenet­ic complete hydatidifo­rm mole — in which there are no maternal chromosome­s. What the MUHC team found is that a defective gene (at least in the mouse model) causes the egg to lose all its chromosome­s, rather than half, rendering the egg empty. Thus, no embryo ever forms. “Somehow we answered a question that was open for the last 40 years,” Slim said. For Lafond, though, she faces what she calls a “big question mark” in her future, whether to try again to have another baby. There’s also the possibilit­y of adoption. “My doctor said it’s worth trying again, but the risks are very present,” she said. “My husband and I are discussing it. But I can’t hide that it’s been hard on us.”

 ??  ?? Isabelle Lafond, who gave birth to daughter Raphaëlle Deshaies in 2015, also experience­d two complete molar pregnancie­s, in which no fetus develops and the placental tissue grows into an abnormal mass.
Isabelle Lafond, who gave birth to daughter Raphaëlle Deshaies in 2015, also experience­d two complete molar pregnancie­s, in which no fetus develops and the placental tissue grows into an abnormal mass.

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