Monosomy 20p due to a de novo del(20)(p12.2). Clinical and radiological delineation of the syndrome.

A 16 year-old boy with monosomy 20p was studied. The clinical and radiological data compared with those from the three previously reported cases, permit the delineation of a distinct syndrome of low birthweight, flat face, low nasal bridge, long philtrum, short neck, small overfolded ears, chest deformity, kyphoscoliosis, congenital heart defect, hypoplastic or absent ribs and rachischisis (butterfly-shaped vertebral bodies). The critical chromosome segment causing this syndrome is tentatively defined as 20p13.