Biomarkers in human sperm have been discovered that may specify whether a father is likely to have a child with autism.
Scientists at Washington State University, Valencia Clinical Research Centre and Valencia University in Spain investigated sperm epigenetics and discovered a set of genomic features, called DNA methylation regions, in sperm samples from men who had autistic children. With this information the scientists conducted a series of blind tests to determine whether they could predict which men had autistic children. The results of these tests showed that they were able to predict men who had fathered autistic children with 90 percent accuracy.
'We can now potentially use this to assess whether a man is going to pass autism on to his children,' said Professor Michael Skinner, corresponding author on the study. 'It is also a major step toward identifying what factors might promote autism.'
The researchers examined 26 men: 13 who had sons with autism, and 13 who had children without the disorder. They discovered 805 different DNA methylation regions that they believe can potentially act as epigenetic biomarkers for a predisposition to father children with autism. In the blind tests that followed, the researchers looked at whether sperm samples had these key DNA methylation regions and correctly identified whether men had fathered autistic children in 16 of the 18 samples.
The scientists state in their paper, published in the journal Clinical Epigenetics, that although significantly more validation with larger clinical test sets is needed, the current study provides the proof of concept that epigenetic biomarkers potentially exist and may be used to diagnose that a father may have a child with a susceptibility for autism. Professor Skinner and his colleagues are currently working on a more extensive study involving over 100 men.
Autism spectrum disorder prevalence has increased from 1 in 5000 people in 1975, to 1 in 68 in 2014. Better awareness of the disorder and improved diagnosis can explain some of this increase, but some scientists believe that the increase may be due to molecular and environmental factors. Furthermore, studies have shown that autism can be passed down to future generations and this transmission is higher from fathers than mothers.
'With further research, this biomarker could also be used to trace how the epigenetic changes occurred in the first place', said Professor Skinner. 'We found out years ago that environmental factors can alter the germline, the sperm or the egg epigenetics... With this tool we could do larger population-based studies to see what kinds of environmental factors may induce these types with epigenetic changes.'