Chromosome abnormality caused by a small deletion on the short arm (p) of chromosome 1.
People with 1p36 deletion syndrome have intellectual disabilities and about half have some form of behavioural disorder. Motor development is delayed and many have low muscle tone (muscular hypotonia) and hypermobility of the joints. Epilepsy is very common. Both hearing and vision may be affected. Some individuals with the syndrome have anomalies of the central nervous system, such as hydrocephalus or cerebral atrophy. In new-born babies, closing of the fontanelles is often delayed. Other deformities may occur, the most common being heart defects of different types and severity (approx. 50%), cleft lip and palate (approx. 30%) and abnormalities in the kidneys and urinary tract (approx. 20%). Other relatively common symptoms are poor function of the thyroid gland, skeletal abnormalities and skin changes. Many infants with this syndrome show stunted growth from birth onwards. There is a gradual improvement in motor skills, communication and behavioural problems as they grow up.
Partial monosomy 1p36 syndrome.
Characteristic facial features are associated with the diagnosis. Cleft lip and palate is common. Malocclusion may occur. Oral-motor development is often delayed and the associated muscles are inactive and hypotonic. Difficulties in sucking, eating and drinking and reduced saliva control are common. Speech, language and communication skills are generally affected.