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New Genetic Test for Autism Found Superior to Current Tests

A large study from Children's Hospital Boston and the Boston-based Autism Consortium, and collaborating institutions, has found that a genetic test known as chromosomal microarray analysis (CMA), which samples the entire genome, has about three times the detection rate for genetic changes related to autism spectrum disorders (ASDs) than standard tests. The authors urged that CMA become part of the first-line genetic work-up for ASDs. Because of the dramatic increase in variations identified using CMA, the Autism Consortium recommends that CMA should be included in the first tier of diagnostic testing for children with ASD symptoms that have no clear genetic cause. Expectant parents who have family members with ASDs, as well as families who already have an affected child, often request genetic testing. However, there is still only limited knowledge about actual causative genes. The currently recommended tests (karyotyping to look for chromosomal abnormalities and testing for Fragile X syndrome, the single most frequent known genetic cause of ASDs), often come up negative. CMA is a genome-wide assay that examines the chromosomes for tiny, sub-microscopic deletions or duplications of DNA sequences, known as copy-number variants. CMA offers about 100-fold greater resolution than standard karyotyping. However, because it is new, it is often considered a second-tier test. Depending on where a person lives, or what insurance he or she has, CMA may not be covered by health insurance. "Based on our findings, CMA should be considered as part of the initial clinical diagnostic evaluation of patients with ASDs," said Dr. Bai-Lin Wu, co-senior author of the report and Director of Children's Hospital Boston’s DNA Diagnostic Lab, which has offered CMA to families since 2006. "CMA clearly detects more abnormalities than other genetic tests that have been the standard of care for many years," said Dr. David Miller, of Children’s Hospital Boston’s Division of Genetics and Department of Laboratory Medicine and also a co-senior author of the report. "We're hoping this evidence will convince insurance companies to cover this testing universally." This research was published online on March 15, 2010 in Pediatrics. [Press release 1] [Press release 2] [Pediatrics abstract]