Clinical: Deletions and duplications at chromosome 16p11.2 appear to be associated with ~1% of unexplained, idiopathic and nonsyndromic autism. Developmental regression which affects ~40% of children with late-onset autism was not seen in Weiss' study indicating that 16p11.2 deletion or duplication events are mostly associated with autism of early onset. The penetrance of autism in individuals with this deletion is unknown since in Weiss studied families with autism. Indeed there is a suggestion that autism is not an obligatory consequence of this deletion since a case report by Ghebranious describes a child with the same deletion who had aortic valve disease, seizures and mild mental retardation.

Size of deletion/duplication: The deletion measures ~600kb and the breakpoints appeared identical in all 8 children studied by Weiss and the same as for the 11 individuals with the duplication. There are more than 25 genes or transcripts in the critical interval as well as rapidly evolving genes in the flanking duplications.

Origin of deletion/duplication: Of the 13 indiviudals reported by Weiss, the rearrangements arose de novo in 10, was inheirted from parents with ADHD or mental retardation in 2 and was unkown in one. Interspersed duplicaion blocks (12 and 13) on 16p11.2 promote unequal crossing over during meiosis (NAHR).

Expert advisor:

Links to support groups:

www.rarechromo.org

Links to further information:

CNV Syndromes / 16p11.2 microduplication syndrome