1p36 deletion syndrome (monosomy 1p36)

Monosomy 1p36 is caused by a loss of genetic information on the short arm of chromosome 1. It occurs in about two of every 10,000 births. Most of the children affected by 1p36 deletion syndrome have severely delayed development accompanied by behavioural problems and self-destructive behaviour. General hypotonia and feeding difficulties are common, as are cerebral seizures. In addition to distinctive physical features, vision problems and loss of hearing, about 40 per cent of the affected children also have heart defects. The ductus botalli frequently remains open; tetralogy of Fallot is a common occurrence, as are cardiac septal defects, known as Ebstein’s anomaly, and dilated cardiomyopathy.