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Noonan syndrome: a cryptic condition in early gestation
R Achiron1, J Heggesh, D Grisaru
1Department of Obstetrics and Gynecology, The Chaim Sheba Medical Center, Tel Hashomer, Israel.
American Journal of Medical Genetics
|May 19, 2000
Summary
Noonan syndrome, a common genetic disorder, often presents subtly in utero. Early ultrasound findings may resolve, with typical signs appearing later, complicating prenatal diagnosis of Noonan syndrome.
Area of Science:
- Medical Genetics
- Prenatal Diagnosis
- Pediatric Cardiology
Background:
- Noonan syndrome is a common genetic disorder with variable presentation.
- Prenatal diagnosis is challenging, often missed in early pregnancy.
- Typical features may evolve during gestation and after birth.
Purpose of the Study:
- To investigate the spectrum of ultrasonographic findings suggestive of Noonan syndrome in fetuses.
- To assess the reliability of early and late-term ultrasound markers for prenatal diagnosis.
- To understand the evolving in utero and postnatal phenotype of Noonan syndrome.
Main Methods:
- Retrospective analysis of ultrasonographic data from four fetuses diagnosed with Noonan syndrome.
- Review of medical records for clinical and postnatal follow-up.
- Correlation of in utero findings with postnatal diagnoses and outcomes.
Main Results:
- Early transient findings (nuchal translucency, neck cysts) resolved in one fetus.
- Later-onset findings (hydrothorax, edema, polyhydramnios) were observed in the third trimester for three fetuses.
- Facial features (low-set ears, depressed nasal bridge) and cardiac defects (pulmonic stenosis, cardiomyopathy) were noted.
- Postnatal diagnosis was often delayed despite suggestive in utero signs.
Conclusions:
- Noonan syndrome exhibits an evolving phenotype, impacting prenatal detection.
- Amelioration of early signs and late onset of typical features limit early diagnosis.
- Further research is needed to improve prenatal identification of Noonan syndrome.