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Saliva Testing Can Reveal Mosaic CNVs Important in Intellectual Disability

Researchers in the European Journal of Human Genetics recommend salivary microarray as a first-tier test for syndromic intellectual disability. In their study, they compared the yield of chromosomal microarray testing of both blood and saliva samples from 370 individuals, 224 with syndromic ID and 146 with isolated ID. Within this cohort, they found that the diagnostic yield for mosaic pathogenic CNVs was higher in saliva than blood samples. For instance, testing uncovered 20 samples with clinically relevant mosaicism when saliva was tested as compared to one when blood was tested. Mosaicism levels within saliva ranged, the researchers note, between 5 percent and 40 percent for CNVs. Meanwhile, they also found that for non-mosaic CNVs, the results were consistent between blood and saliva samples. "We suggest that in individuals with syndromic ID, saliva or buccal genomic testing be performed as the first-tier test over blood testing," researchers led by Meaghan Wall from Murdoch Children's Research Institute write in their paper.