ASD is an umbrella term for a collection of pervasive developmental disorders. This term replaces previously used diagnostic terminology, including autistic disorder, Asperger syndrome, Rett syndrome, childhood disintegrative disorder and pervasive developmental disorder – not otherwise specified.2
ASD is characterised by impaired social communication and interaction, limited interests, and repetitive behaviours. Markers of ASD usually appear during the first two years of life, in particular, problems with language development and social relatedness.3
Some rare genetic conditions show clinical features that are characteristic of ASD. These include:
- tuberous sclerosis (TSC1 or TSC2 genes)
- Fragile X syndrome (FXS; FMR1 gene)
- chromosomal abnormalities (eg inversions, duplications)
- metabolic conditions
- Rett syndrome (MECP2 gene in many cases).