The role of genetic testing in small for gestational age infants.

Small for gestational age (SGA) infants face increased morbidity, mortality, and long-term health risks, yet causes of SGA remain unclear. While placental insufficiency and environmental factors contribute, genetic disorders play a significant role. Syndromes like Silver-Russell and Noonan are linked to SGA, but the overall genetic contribution remains uncertain. We reviewed literature on genomic sequencing in SGA and fetal growth restriction (which often precedes SGA) and identified 161 single-gene disorders. The top ten genes explained one-third of cases, but half were attributable to unique genes. Genetic disorders were frequently accompanied by congenital anomalies (often skeletal dysplasia) and developmental delays. Current guidelines for genetic evaluation of SGA are limited. Our findings support consideration of exome or genome sequencing, particularly in the setting of congenital anomalies or developmental delays. Early identification of genetic disorders can enable tailored therapy. Given the complexity of the SGA genetic landscape, prospective genomic studies are urgently needed.