Babies with Prader-Willi Syndrome Have Higher Rate of Perinatal Complications

Perinatal complications, including hypotonia (low muscle tone) and feeding difficulties, are clinical features more common among newborns with Prader-Willi syndrome, compared with the general population, according to a new study.

The study with that finding, “Multicentre study of maternal and neonatal outcomes in individuals with Prader-Willi syndrome,” was published in the Journal of Medical Genetics.

A lack of expression of genes located on one part of chromosome 15 is responsible for the development of Prader-Willi syndrome (PWS). There are three different genetic subtypes responsible for PWS: paternal deletion of 15q11-q13, maternal uniparental disomy (UPD), when two copies of a chromosome come from the mother and none from the father, and; imprinting defects, in which the paternal chromosome is improperly silenced.

Babies with PWS tend to exhibit hypotonia, poor sucking ability, and feeding difficulties, dysmorphic features and hypogonadism (reduction or absence of hormone secretion).

Features of PWS in the perinatal period (the time immediately before and after birth) include decreased fetal movements, polyhydramnios (excessive accumulation of amniotic fluid), malpresentation, and fetal heart rate abnormalities.

However, most perinatal features that have been described in literature are part of clinical reports or small case series. Increased awareness on such features among obstetricians and healthcare providers could allow for earlier diagnosis and treatment of PWS.

That’s why researchers set out to identify and compare frequencies of prenatal and neonatal clinical features of PWS among the three genetic subtypes of the disease. This was a large-scale study that included 355 subjects enrolled in the National Institutes of Health (NIH) Rare Disease Clinical Research Network (RDCRN) PWS registry.

In the study group, 61% of the patients had paternal deletions, 36% had UPD, and 3% had imprinting defects.

Pre-birth, fetal movements were reduced in 72% of the fetuses. Post-birth, all babies were hypotonic, and 99% had feeding difficulties. The use of a feeding tube was required in most babies, with 25% requiring gastrostomy tube placement.

Babies with PWS also were found to be at a high risk for low birth weight (less than 2500 grams).

When comparing the different PWS subtypes, researchers determined there were no significant differences (with the exception of the UPD group) in which mothers tended to be significantly older and weigh more in the pre-pregnancy period.

In summary, researchers concluded: “We found a higher rate of perinatal complications in PWS syndrome compared with the general population. No significant differences in the genetic subtypes were noted except for a higher maternal age and pre-pregnancy weight in the UPD subgroup.”