18. Trisomy 18p detected in DNA from saliva but absent in DNA from blood

Abstract

Molecular diagnostic testing using DNA from saliva specimens markedly increased recently due to the ease of sample collection, compared to peripheral blood, during the COVID-19 pandemic. Published literature suggests that DNA from saliva is primarily composed of epithelial cells (70-90%), with the remainder being primarily leukocytes (10-30%). Here, we describe a case followed by our clinicians since 2007 characterized by developmental delay, autism, a somewhat coarse face with full cheeks, up-slanting palpebral fissures, thin corpus callosum, and a full-scale IQ of 60.