Researchers have long suspected that genetics plays a role in autism(自閉症), observing that many families have multiple children with the disorder, and have now identified a rare chromosomal(染色体の)defect that accounts for 1% of all autism cases.
While in some cases this defect is inherited, it is more often the result of a random genetic mutation(突然変異). Until now, about 10% of autism cases have been attributed to known causes like Fragile X syndrome(フラジャイルエックス症候群)or congenital(先天的な)rubella(風疹). This new discovery leaves another 89% of cases to be explained.