Yield of Standard Genetic Testing in a Large Autism Diagnostic Clinic

Background: Children with possible ASD routinely undergo genetic testing as part of a diagnostic assessment.  Reports vary regarding the diagnostic yield of genetic testing. Objectives: Review yield of genetic testing in a large diagnostic clinic for children with ASD. Methods:   Records of 360 children (316 male) diagnosed with ASD via ADOS and clinical evaluation were reviewed (group 1).  Frequency of genetic testing being obtained was assessed, and abnormal results were tallied.  Records of 52 additional children, referred for expanded cytogenetic microarray testing because of a formal or suspected diagnosis of autism were also reviewed (group 2).

Results: 61.4% of group 1 underwent routine chromosome analysis, with a yield of one abnormal result.  57% of group 1 underwent DNA probe for FX syndrome, with one abnormal result. Four patients in group 2 (7.6%) had abnormal results on expanded cytogenetic microarray, including 22q13 deletion,15q11.2 duplication,10q23 duplication and 1q12q21.3 duplication.  One of these patients was found to not have autism according to ADOS.  Remaining 3 patients had final diagnoses of autism based on ADOS and/or clinical evaluation.  Additional cases to be added at time of presentation.

Conclusions: Yield of routine chromosome analysis and DNA probe for FX in children with ASD may be lower than that of expanded cytogenetic microarray.