Spinal Muscular Atrophy: Inheritance, Screening, and Counseling for the Obstetric Provider.

IMPORTANCE: Spinal muscular atrophy (SMA) confers significant risk of neonatal and infant morbidity and mortality. Screening women during or before pregnancy for carrier status of SMA presents an opportunity to identify pregnancies at risk for this potentially devastating condition. OBJECTIVE: The objective of this review is to describe the different forms of SMA and their inheritance. In addition, this review guides obstetric providers in interpreting results of carrier screening. EVIDENCE ACQUISITION: A MEDLINE search of "prenatal genetic testing," "spinal muscular atrophy," and "inheritance of spinal muscular atrophy" in the review was performed. RESULTS: The evidence cited in this review includes 4 medical society committee opinions and 14 additional peer-reviewed journal articles that were original research or expert opinion summaries. CONCLUSIONS AND RELEVANCE: Spinal muscular atrophy is a severe, heterogeneous neurodegenerative disorder. The American College of Obstetricians and Gynecologists recommends that obstetricians offer carrier screening for SMA to all pregnant women. Given the different types and inheritance of SMA, understanding of the disease and interpreting carrier screening results is of paramount importance to the prenatal care provider.