Case report suggests signs of Prader-Will syndrome during pregnancy

During pregnancy, Prader-Willi syndrome (PWS) can manifest as excess fluid around the developing fetus associated with restricted fetal growth and decreased fetal movement, according to a new report.

These signs should alert clinicians to consider testing for the possibility of a diagnosis of PWS, the researchers wrote.

The report, “Cardiac rhabdomyoma as a possible new prenatal ultrasound feature of Prader-Willi syndrome, ”Was published in the Obstetrics and Gynecology Research Journal.

Thai scientists have described the case of a 40-year-old woman referred to their center. It was the woman’s third pregnancy. The first was normal, with a cesarean delivery, due to an uneasy fetal heartbeat. The second ended with an elective abortion after the fetus had trisomy 21 (also known as Down syndrome).

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Due to advanced maternal age and a history of genetic defects, she underwent genetic amniocentesis, a test that looks for large genetic abnormalities in the developing fetus. The results were normal and the pregnancy seemed to go off without incident for the first few months.

At week 28 of pregnancy, a routine ultrasound revealed hydramnios, an abnormally large amount of fluid around the developing fetus.

Another ultrasound screening three weeks later again showed hydramnios. Although the fetus had normally shaped extremities, it was abnormally small (weight estimated at the 10th percentile) and no fetal movement was observed over one hour of observation.

Additionally, imaging revealed a small rhabdomyoma – a rare type of tumor – on the unborn baby’s heart.

The woman and her partner were counseled to discuss these results. Ultimately, because the fetus had no obvious deformities and the pregnancy was quite advanced, they decided to wait until the baby was born to perform further genetic testing.

During the remainder of her pregnancy, the woman had regular tests to check for potential problems. Aside from a continued lack of fetal movement, the pregnancy was normal and at 38 weeks the baby was born by elective cesarean section.

The woman gave birth to a boy weighing 2,420 grams (5.3 pounds), placing him in the 8th percentile. Several abnormalities were noted, including hypotonia (poor muscle tone), a thin upper lip, and underdeveloped genitals.

“The newborn survived, although [he] had several clinical problems, especially a difficult diet, ”the researchers reported.

The combination of signs and symptoms before and after birth led the baby’s healthcare team to suspect PWS, so a genetic test was ordered. The results were positive for PWS, confirming the diagnosis. Even though the baby had poor muscle tone and poor sucking, breastfeeding was successful with special care from the mother.

Mental and physical impairments were not evident at two months. Growth was somewhat retarded, but was within the normal range. Still, the baby was scheduled for close follow-up.

The researchers concluded that “the prenatal ultrasound features of hydramnios, decreased fetal movement, and restriction of fetal growth should alert doctors to mention PWS” as a possible diagnosis.

The team also noted that, since PWS and rhabdomyoma are extremely rare individually, finding them both in the same patient indicates a potential link.

Although they recognized that this “could be a chance finding,” the team said it would be useful to document whether the two conditions tend to coexist, as rhabdomyoma may be “a possible new prenatal ultrasound marker of SPW “.

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