Abstract
We report the sonographic features of a fetus affected with Jacobsen syndrome that led to prenatal cytogenetic diagnosis. Among the observations include a *trigonocephalic cranium with marked hypotelorism; micrognathia and prominent anteverted nares; an echogenic protuberance in the midsternum suggestive of a fleshy mass; unusually short femur; and presence of polyhydramnios. The case presented demonstrates that partial monosomy for the distal long arm of chromosome 11 (Jacobsen syndrome), may be suspected on detection of associated prenatal sonographic findings. Ultimately, however, cytogenetic analysis is required for diagnosis. Identification of an unbalanced translocation in the fetus warrants genetic counseling and parental chromosomal analysis.