Mosaicism for the Wolf-Hirschhorn syndrome, del(4)(p16), is extremely
rare and has not been reported in association with a numerical chromos
ome abnormality. We report the prenatal diagnosis of mosaic del(4)(p16
) and non-mosaic trisomy 21 in a 16-week female fetus. The pregnancy e
nded in spontaneous abortion at 34 weeks secondary to fetal demise. Th
e fetus had features of both 4p - and trisomy 21.