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Brief report: parental age and the sex ratio in autism

Alene Anello1, Abraham Reichenberg, Xiaodong Luo

  • 1Harvard University, Cambridge, MA, USA.

Journal of Autism and Developmental Disorders
|May 20, 2009
PubMed

Insights

The male-to-female ratio in autism spectrum disorders (ASD) decreases as fathers age. This finding suggests paternal age influences ASD sex ratios, potentially due to genetic factors.

Area of Science:

  • Genetics
  • Neurodevelopmental Disorders
  • Reproductive Health

Background:

  • Autism spectrum disorder (ASD) affects males more than females, with a typical male-to-female ratio of 4:1.
  • The influence of parental age on the sex ratio of ASD has not been systematically investigated.

Purpose of the Study:

  • To examine the relationship between paternal age and the male-to-female ratio in autism spectrum disorder.
  • To investigate the association between maternal age and the male-to-female ratio in ASD.

Main Methods:

  • Analysis of 393 autism spectrum disorder cases from families with multiple affected siblings.
  • Categorization of paternal age into five groups: <30, 30-34, 35-39, 40-44, and 45+.
  • Statistical adjustment for maternal age in the analysis of paternal age effects.

Main Results:

  • A significant decrease in the male-to-female ratio for autism spectrum disorder was observed with increasing paternal age groups.
  • This association remained significant after adjusting for maternal age.
  • No significant relationship was found between maternal age groups and the autism spectrum disorder male-to-female ratio.

Conclusions:

  • Increasing paternal age is associated with a reduced male-to-female ratio in autism spectrum disorder.
  • This finding supports the hypothesis that de novo genetic or genomic anomalies, which increase with paternal age, may influence the sex ratio of ASD.
  • Paternal age is a significant factor in the sex distribution of autism spectrum disorder.

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