Prenatal Diagnosis of X-Linked Chondrodysplasia Punctata 2 Presented with Calcific Stippling in Ribs and Postaxial Polydactyly Identified in the First Trimester: A Case Report.

X-linked chondrodysplasia punctata 2 (CDPX2) is a genetic disorder characterized by skeletal, cutaneous, and ophthalmic abnormalities. In this study, we present with a fetal case of CDPX2 which was identified in the first trimester by ultrasound and was confirmed by molecular diagnosis. The 12-week ultrasound revealed that nearly the entire thorax exhibited irregular rib-like stippling in the four-chamber view with postaxial polydactyly in the right hand. A follow-up ultrasound at 16+1 weeks demonstrated persistent findings along with evidence of a narrow thorax and shortened limbs. Trio exome sequencing identified a de novo pathogenic EBP variant c.146T>A, p.(Leu49Ter). Our case serves as further evidence that first-trimester ultrasounds can detect structural anomalies, thus offering opportunities for early diagnosis of genetic syndromes and allowing timely management decisions regarding pregnancy.