SOS2 and Noonan syndrome: Although the KRAS gene is not linked to ASD, ASD was observed in Patient 040110, presumed compound heterozygous variants in LZTR1 in Patient 029623, and a de novo variant in SOS2 in Patient 023509, are a probably causative in all three patients since ADHD and behavioral problems are reported in the Noonan syndrome phenotype (Roberts, 2001).