While the causes of autism spectrum disorder (ASD) are not fully understood, researchers believe both genetics and environment play a role.
In some cases, the disorder is linked to de novo mutations that appear only in the child and are not inherited from either parent’s DNA.
In a new study, researchers found that a new sperm test may reveal the risk of autism in future children.
They report a method to measure disease-causing mutations found only in the sperm of the father, providing a more accurate assessment of ASD risk in future children.
The research was conducted by an international team led by the University of California San Diego.
Autism afflicts one in 59 children and a big portion is caused by these de novo DNA mutations.
De novo mutations occur spontaneously in parents’ sperm or eggs or during fertilization. The mutation is then present in each cell as the fertilized egg divides.
Recent studies suggest gene-damaging de novo mutations are involved in at least 10% to 30% of autism cases, with the number of mutations rising with the father’s age at the time of conception.
Studies now point to male sperm as a particularly important source of these mutations, with the chance of the mutation recurring within the same family generally estimated at 1% to 3%.
However, such estimates are not based on actual knowledge of the risk in an individual family but instead are based on frequencies in the general population.
In the study, the team used the Comet supercomputer based at the San Diego Supercomputer Center to align the whole genome sequences.
They analyzed the sperm of eight fathers who were already parents of children with autism.
Using deep whole-genome sequencing, the team found variants in offspring that were matched only in the fathers’ sperm.
They determined that disease-causing mutations were present in up to 15% of the fathers’ sperm cells, information that could not be determined through other means, such as blood tests.
The team says with the new study, scientists can trace some of these mutations back to the father, and they can directly assess the risk of these same mutations occurring again in future children.
One author of the study is Jonathan Sebat, a professor and chief of the Beyster Center for Molecular Genomics of Neuropsychiatric Diseases.
The study is published in Nature Medicine.
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