Prenatal diagnosis of mosaicism 46,XX/46,XX,-21,+t(21q21q)

Mosaicism for a structural chromosome abnormality in amniotic cell cultures indicative of true fetal mosaicism is a rare event. In addition to the laboratory findings the clinical interpretation for counseling in such cases is based on observation of the same abnormality in liveborns as well as previous experience with prenatal diagnosis of the same or similar abnormalities. We report here the prenatal diagnosis of 46,XX/46,XX,-21,+t( 21q21q ) which was confirmed in fetal skin cell and amnion cell cultures.