Genetic testing for autism spectrum disorders is not just about finding the gene.  So many genes have been found that genetic testing allows families who have a rare genetic disorder to find each other, support one another, raise money for research and train physicians to better help their community.  While genetic testing isn’t always pushed, it should be.  Autism Science Foundation has organized an initiative called AGENDA (www.alliancegenda.org) to bring together rare diseases associated with ASD.  This is important in moving from discovery to development faster.
https://www.ncbi.nlm.nih.gov/pubmed/31542846
https://www.ncbi.nlm.nih.gov/pubmed/31548702