Beyond chromosome analysis: Additional genetic testing practice in a Down syndrome clinic.

Down syndrome (DS) and other genetic conditions have been reported to co-occur in the same person. This study sought to examine the genetic evaluation beyond chromosome analysis of individuals with DS at one DS specialty clinic. Retrospective chart review of genetic testing performed beyond chromosome analysis, the indication for the genetic testing, and the result of the genetic testing from the electronic health record was performed. Demographic information was collected and summary statistics, including mean and frequency, were calculated. The charts of 637 individuals with DS were reviewed. Overall, 146 genetic tests in addition to routine chromosome analysis were performed on 92 individuals with DS. Tests included chromosomal microarray, gene panels, and whole exome sequencing. Tests were performed for the indication of: autism spectrum disorder, celiac disease, dementia, hematologic diseases, and others. Eleven individuals with DS were found to have a second genetic diagnosis. Individuals with DS in one multidisciplinary clinic for DS had a variety of genetic tests beyond chromosomes completed, for varied indications, and with some abnormal results leading to additional diagnoses. Additional genetic testing beyond chromosome analysis is a reasonable consideration for patients with DS who have features suggestive of a secondary diagnosis.