Washington D.C. [USA] Sep 9 (ANI): When an individual develops a neurodevelopment disorder like autism the severity of that disorder depends on genetic changes beyond a single supposedly disease-causing mutation. The total amount of rare mutations - deletions duplications or other changes to the DNA sequence in a person's genome can explain why individuals with a disease-associated mutation can have vastly different symptoms. Senior author of the paper Santhosh Girirajan said Genetic sequencing tools can reveal a large number of mutations in a person's genome but diagnosis typically focuses on identifying one primary mutation as the cause of a disorder.