Prenatal Diagnosis of Arthrogryposis Multiplex Congenita (AMC): Ultrasound and Genetic Findings in 69 Fetuses From 67 Unrelated Families

ABSTRACT Objective To investigate the ultrasound features and genetic etiology of fetuses with arthrogryposis multiplex congenita (AMC) to improve prenatal counseling. Methods This retrospective study included 69 fetuses from 67 unrelated families diagnosed prenatally with AMC who underwent genetic testing between 2020 and 2024. Clinical data, including prenatal ultrasound findings, genetic testing results (conventional chromosome analysis, chromosomal microarray analysis CMA/copy number variation sequencing CNV‐seq, CNV‐seq‐PLUS, and exome sequencing ES) were systematically reviewed as well as pregnancy outcomes. Results The most common prenatal ultrasound finding was clubfoot, observed in 50.7% (35/69) of fetuses. Abnormalities in other systems occurred in 84.06% of cases (58/69), with an abnormal facial profile being the most frequent, detected in 30.43% (21/69). Aneuploidy and pathogenic copy number variations (CNV) were identified in 10.45% (7/67) of the unrelated families. By exome sequencing, we identified causative variants in 14 of 42 families with negative karyotype and CNV results, yielding a diagnostic rate of 33.33% (14/42) Pregnancy outcomes were available for 62 cases, with a high rate of termination (95.16%, 59/62). Among the three newborns, two died in the neonatal or infantile period, and only one survived with persistent arthrogryposis. Conclusion A comprehensive joint and movement assessment is essential when clubfoot is detected. AMC can occur at any stage of pregnancy and exhibits phenotypic heterogeneity. Regular follow‐up ultrasounds are essential. ES significantly improves the diagnostic yield by providing key information for genetic counseling.