Partial deletion of the short arm of chromosome 20: 46,XX,del(20)(p11)/46,XX mosaicism.

A 46,XX/46,XX,del(20)(p11) mosaicism was identified in a 10-month-old female infant with multiple congenital anomalies, development retardation and failure to thrive. The 20p partial deletion was observed in 50% of the cells examined. Both parents had normal phenotype and karyotype. Only four other patients with partial 20p deletion are known and they are not mosaics. Their clinical findings are similar to those of our patient; in particular, they share anomalies of the vertebral column such as segmentation errors and "butterfly-shaped" vertebrae.