Some men who have an autistic child carry mutations linked to the condition only in their sperm, according to a new study. In these men, genetic tests of sperm, rather than of blood, may help estimate their chances of passing the mutations to future children.
The study involved 20 families with an autistic child; most of the children carry mutations strongly linked to the condition. Previous studies did not detect these mutations in the blood of the parents, so researchers assumed that the mutations occurred spontaneously in the parents’ egg or sperm.
[Researcher Joseph] Gleeson and his colleagues used sensitive sequencing methods to analyze the fathers’ sperm.
Spontaneous mutations found in a child are thought to have about a 1 percent chance of appearing in later-born siblings.
The new results suggest that these odds are much higher for children of men who carry mutations in their sperm. The exact odds may depend on the proportion of sperm cells that carry the mutation.
“We need to be able to separate the few families with high risk from the others that have a negligible risk, and for that you can use sperm,” says [geneticist] Anne Goriely.