Mental health articles

Within each syndrome there is a degree of variability. Given that behavioural phenotypes involve probability statements, not everyone with a given syndrome will exhibit that syndrome’s characteristic behaviours.

For example, studies have found that patients with Down syndrome (both children and adults) are more likely to show specifi c deficits in grammar, expressive language and articulation, than other people with ID, but do not do so invariably. Similarly, those with fragile X syndrome or with Williams syndrome are more likely to be hyperactive, and those with Prader–Willi syndrome to have obsessions and compulsions.

Sometimes a particular behaviour is characteristic of, although not necessarily unique to, a particular genetic aetiology, for example: hyperphagia in Prader–Willi syndrome; extreme self-mutilation in Lesch–Nyhan syndrome; schizophrenia in adults with velocardiofacial syndrome; the insertion of foreign objects into bodily orifi ces (along with the ‘self-hugging’) in Smith Magenis syndrome.

Tags: behavioural, phenotypes