Chromosome 17q21.31 Microdeletion in a Patient with Autism

Background: Recent findings suggest that microdeletions/microduplications of chromosomal regions involved in mental retardation also play an important role in autism. A new 17q21.31 microdeletion syndrome, caused by non-homologous recombination mediated by low copy repeats, was recently described in 11 individuals after screening large cohorts of patients with mental retardation. The subjects had overlapping deletions between 500 kb and 650 kb and they all had developmental delay, hypotonia and characteristic facial features.

Objectives: The purpose of this study was to ascertain the involvement of 17q21.31 microdeletions in autism by screening a large group of patients with autism spectrum disorders.

Methods: A total of 374 patients with an autism spectrum disorder belonging to 305 families recruited by the Paris Autism Research International Sibpair (PARIS) study were screened for deletions and duplications associated with mental retardation syndromes using multiplex ligation-dependent probe amplification (MLPA). Positive findings were confirmed with quantitative PCR.

Results: We identified one patient with a microdeletion at 17q21.31. Characterization of the breakpoints with qPCR showed that the deletion had an approximate size of 700 kb, and comprised six known genes, including MAPT and CRHR1. The deletion was not present in the mother; the father was deceased and no DNA was available. The girl had delayed motor and speech development, as well as mild dysmorphic features similar to the ones described previously, including long face, blepharophimosis, bulbous nasal tip, broad chin and long fingers. At 11 years of age, she fulfilled diagnostic criteria for autistic disorder and had a global IQ of 40.

Conclusions: This is the first report of a 17q21.31 microdeletion associated with autism. Although the prevalence appears to be low, this observation adds to the increasing list of genomic disorders involved in the etiology of autism.