Mid-trimester absent nasal bone and transient unilateral hydronephrosis associated with 16p13.3 microduplication.

Characteristic phenotypic features of 16p13.3 microduplication include impaired mental development, arthrogryposis-like musculoskeletal anomalies (club-feet, congenital hip dislocation, and camptodactyly of fingers and toes), facial dysmorphology, and at times congenital cardiac disease. Most of the described affected individuals have microduplications involving the CREBBP gene. Findings indicate this gene to be dosage-sensitive and likely involved in the phenotypes of 16p13.3 microduplication syndrome. We describe the incidental finding of 16p13.3 microduplication in a fetus with mid-trimester sonographic examination showing absent nasal bone and transient unilateral hydronephrosis.