Prenatal diagnosis of a novel pathogenic variation in the ACAN gene presenting with isolated shortening of fetal long bones in the second trimester of gestation: a case report.

Heterozygous mutations of the ACAN gene are a major cause of different evolutive growth defects in the pediatric population, but were never described as a cause of fetal skeletal dysplasia. A G1 at 21w + 3d came to our institution for the second-trimester ultrasound and a skeletal dysplasia with prevalent involvement of limb’s rhizomelic tracts was suspected. Amniocentesis followed by CGH-array was performed, with normal results. An examination by NGS of some genes associated with skeletal dysplasias showed a novel pathogenic variant of the ACAN gene: c.2677delG. Sequence variations of ACAN were never described as a possible cause of fetal skeletal anomalies to date. In this case report, we describe the first prenatal diagnosis of skeletal dysplasia associated with a pathogenic variant of ACAN.