Autism genes have been difficult to identify, despite the high heritability of autism spectrum disorders. Up to 10% of autism cases may be due to rare sequence and gene dosage variants, for example, mutations in NRXN1, NLGN3/4X, SHANK3, and copy number variants at 15q11–q13 and 16p11.2. A number of diseases of known etiology, including Rett syndrome, fragile X syndrome, neurofibromatosis type I, tuberous sclerosis, Potocki-Lupski syndrome, and Smith-Lemli-Opitz syndrome are also associated with autism 1,13. However, the remaining 90% of autism spectrum disorders, while highly familial, have unknown genetic etiology. A genome-wide linkage study using the Affymetrix 10K SNP array to genotype over 1,000 families found no genome-wide significant linkage signals, but documented suggestive linkage at 11p12–p13 and 15q23–q25 and reinforced a modest role for rare copy-number variants 14.
