Noonan syndrome: A cryptic condition in early gestation

Reuwen Achiron*, J. Heggesh, Dan Grisaru, Boleslav Goldman, Shlomo Lipitz, Simcha Yagel, Moshe Frydman

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Noonan syndrome is one of the most common of genetic syndromes and manifests at birth, yet it is usually diagnosed during childhood. Although prenatal diagnosis of Noonan syndrome is usually not possible, in a few cases the ultrasonographic findings suggested the diagnosis in utero. Reported sonographic clues include septated cystic hygroma, hydrothorax, polyhydramnios, and cardiac defects, such as pulmonic stenosis and hypertrophic cardiomyopathy. During a 6-year period, 46,224 live-born infants were delivered at the Chaim Sheba Medical Center. Seven newborn infants and four fetuses were found to have Noonan syndrome. One fetus showed transient nuchal translucency of 4 mm and bilateral neck cysts at the 13th gestational week. Both findings resolved spontaneously by the 18th gestational week, but during the third trimester this fetus developed hydrothorax, skin edema, and polyhydramnios. In the three other fetuses, first- and second-trimester ultrasonographic findings were normal, and the diagnosis of Noonan syndrome was suggested only during the third trimester. All three fetuses had polyhydramnios and skin edema. A cardiac malformation, hydrothorax, and a large head were present in one fetus. Sonographic facial findings were investigated. In all four fetuses posteriorly angulated, apparently low-set ears and depressed nasal bridge were identified. Wide nasal base was seen in two fetuses. In two fetuses, persistent opening of the fetal mouth was interpreted as fetal hypotonia. One fetus developed progressive postnatal hypertrophic cardiomyopathy and in one case, pulmonic stenosis became apparent at age 6 months. This small series suggests that Noonan syndrome has an evolving phenotype during in utero and postnatal life. Amelioration of early nuchal region findings and late onset of the more 'typical' ultrasonographic changes may limit early prenatal detectability. (C) 2000 Wiley-Liss, Inc.

Original languageEnglish
Pages (from-to)159-165
Number of pages7
JournalAmerican Journal of Medical Genetics
Issue number3
StatePublished - 29 May 2000


  • Noonan syndrome
  • Nuchal
  • Prenatal diagnosis
  • Ultrasonographic studies


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