First-trimester Diagnosis of Nager Syndrome by Prenatal Sonography with Confirmatory SF3B4 Gene Deletion on Chromosomal Microarray: A Case Report

Abstract Nager syndrome is characterized by craniofacial features like those observed in Treacher Collins syndrome. The associated craniofacial and limb abnormalities include slanted eyelids, midface retrusion, micrognathia, small or absent thumbs, triphalangeal thumbs, radial hypoplasia, and radioulnar synostosis. This report outlines a case of Nager syndrome identified through prenatal ultrasound between 12 and 13 weeks of gestation. The findings included increased nuchal translucency, retrognathia, a single outflow tract with a centrally placed inflow tract (indicative of a common arterial trunk), echogenic kidneys with a prominent pelvicalyceal system, and shortened radius and ulna at 13+1 weeks of gestation. The cytogenomic microarray analysis showed a loss at chromosome 1, specifically at regions 1q21.1 and 1q21.2, including the SF3B4 gene. This report confirms that high-resolution chromosomal microarray analysis (CMA) can diagnose Nager syndrome (NS) genetically in early pregnancy and supports SF3B4 whole gene deletion as a cause of NS. It emphasizes that precise prenatal genetic diagnosis through CMA is achievable when fetal abnormalities are detected via ultrasonography.