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Genetic factors may influence autism risk

Autism may be caused by genetic and moderate nonshared environmental influences, according to data published in JAMA Psychiatry.

The study included data from the Twins Early Development Study, including all twins born in England and Wales from January 1994 through December 1996.

Emma Colvert, PhD, of King’s College London, and colleagues used the Childhood Autism Spectrum Test (CAST) to assess 6,423 pairs (mean age, 7.9 years); the Development and Well-being Assessment (DAWBA) to assess 359 pairs (mean age, 10.3 years); the Autism Diagnostic Observation Schedule (ADOS) for 203 pairs (mean age, 13.2 years); the Autism Diagnostic Interview–Revised (ADI-R) for 205 pairs (mean age, 13.2 years); and a best-estimate diagnosis to estimate outcomes among 207 pairs, according to data.

When the researchers considered all measures, (ie, probandwise concordance rates, diagnostic agreements, twin correlations and bivariate genetic models) they observed significantly greater correlations among monozygotic twins (range: 0.77-0.99) compared with dizygotic twins (range: 0.22-0.65).

When considering DAWBA, ADOS and best-estimate diagnosis measures, the covariance of CAST and ASD status were significantly attributed to additive genetic factors (76%- 95%), according to data. However, shared environmental influences were significant for the ADI-R only (30%; 95% CI, 8%- 47%) compared with genetic influences (56%; 95% CI, 37% to 82%).

“Our findings also confirm that the heritability of the liability to ASD is high when incorporating subclinical cases with high trait scores into the model, extending support for the notion that the genetic liability to autism confers a risk for a broader autism phenotype,” the researchers wrote.

These apparent findings among UK twins 8 years or older suggest genetic and moderate nonshared environmental influences, they added. – by Samantha Costa

Disclosure: The researchers report no relevant financial disclosures.