General information

The TRIO-related intellectual disability syndrome (or Mental retardation autosomal dominant 44 -MIM #617061) is a genetic neurodevelopmental disorder caused by mutations in the TRIO gene, located on chromosome 5.

Main clinical features

The subsequent clinical phenotypes are typically feeding difficulties, microcephaly, global developmental delays affecting both language and motor development, as well as variable degrees of intellectual disability. Behavioural problems including attention deficit – hyperactivity disorder,  autistic traits and/or aggressive behaviour may be part of the clinical spectrum. Most individuals present with minor hand abnormalities.


The exact prevalence of the disorder is unknown.


The disorder is inherited in an autosomal dominant manner. A large subset of the individuals reported has the disorder as a result of a de novo pathogenic mutation but some from a (mildly affected) parent.