A rare chromosomal disorder in which the tip of the short arm (p arm) of chromosome 10 is deleted resulting in a variable phenotype depending on the size of the deletion. The deletion may involve only the terminal 10p15 band, or extend towards the centromere to bands 10p14 or 10p13. Around 50 cases of pure distal monosomy 10p have been reported. The phenotype remains unclear: low birth weight, persistent growth delay, mild psychomotor retardation and hypotonia have been reported, together with single reports of ventricular septal defect, hydrocephalus and hypogenitalia. Distal monosomy 10p generally occurs de novo or may be associated with a parental translocation.