A “snip” (SNP) mutation consists of a one nucleotide change in the DNA strand that makes up a gene. Most such changes have no effect. Some increase risk for a disorder such as autism. Still others decrease risk. Image courtesy of Lauren Solomon, the Broad Institute
Researchers have developed a gene-based test that shows promise for estimating the risk that a child will develop autism before any symptoms appear. Their study appears in the journal Molecular Psychiatry.
“This test could assist in the early detection of the condition in babies and children and help in the early management of those who become diagnosed,” says lead researcher Stan Skafidas, Ph.D., director of the Centre for Neural Engineering at the University of Melbourne. “It would be particularly relevant for families who have a history of autism or related conditions.”
The authors add, however, that their test represents only the first step in the development of a diagnostic test for the future.
In developing the test, the researchers used genetic material and clinical information from Autism Speaks Autism Genetic Resource Exchange (AGRE) and the Simons Foundation Autism Research Initiative databases.
Research suggests that autism results, in part, from a broad array of genetic differences that increase or decrease the risk that a child will develop the disorder. Scientists have struggled to develop a diagnostic test that captures these genetic differences. For this study, the researchers investigated the prevalence of genetic changes called single-nucleotide polymorphisms (SNPs). Each SNP represents a single nucleotide change in the DNA sequence that spells out a gene. SNPs occur often. Most prove harmless. However, they can also increase or decrease susceptibility to developmental disorders such as autism spectrum disorders (ASD).
“Changes in SNPs contribute to our individual differences,” says senior author Christos Pantelis, M.D., of the Melbourne Neuropsychiatry Centre at the University of Melbourne. “The question that we were trying to address in our study is whether a collection of such SNPs are able to act as biomarkers for autism spectrum disorder.”
The new test measures 146 genetic markers of both risk and protection for ASD. The risk markers increase the test score. The protective markers decrease it. The higher the overall score, the higher the individual’s risk.
The test identified ASD with 86 percent accuracy from the genetic samples of a group of families from Utah. It accurately identified ASD in 84 percent of samples from families in Italy. However, it accurately identified only 56 of those of Han Chinese background.
“The use of genetic testing to identify children who may be at risk for developing an ASD as early as possible is promising,” adds Clara Lajonchere, Ph.D. Dr. Lajonchere oversees the AGRE program as Autism Speaks vice president of clinical programs. “Given the extreme heterogeneity of the disorder, however, further research is needed on larger and more diverse samples,” she says. “Only then can we determine whether these estimates of autism risk will prove reasonably accurate to broader segments of the population.”
Importantly, Dr. Lajonchere adds, the use of genetics in clinical practice has the potential to lead to more targeted and personalized approaches for the development of medicines and effective therapeutics.
Next the researchers plan to assess their test among babies born into high-risk families that already have an affected child. In this way, they hope to assess whether their test can discern risk among closely related individuals.
Autism Speaks funds a wealth of cutting-edge research into the genetics and early diagnosis of autism. You can explore these and other studies using our Grant Search.
Reported by Autism Speaks science writer Laurie Tarkan