Telomere Length and Autism Spectrum Disorder Within the Family: Relationships With Cognition and Sensory Symptoms.

Telomeres are repetitive noncoding deoxynucleotide sequences that cap chromosomes to protect DNA. Telomere length (TL) is affected by both genetic and environmental factors, and shortening of telomeres is associated with multiple neuropsychiatric disorders, early life stress, and age-related cognitive dysfunction. Two previous studies associated shorter TL with autism spectrum disorder (ASD). We aimed to replicate this finding, describe TL in unaffected siblings, and explore novel relationships with symptoms and cognitive function in families with ASD. Participants were 212 male children and adolescents ages 1-17 years (86 with ASD, 57 unaffected siblings, and 69 typically developing [TD]) and 64 parents. TL was measured from blood leukocytes with quantitative real-time polymerase chain reaction and results are expressed by relative ratios with a single copy gene. We replicated that children and adolescents with ASD have shorter TL, compared to TD, and show that unaffected siblings have TL in between those of TD and ASD. We present novel associations between TL and sensory symptoms in ASD. Finally, we demonstrate cognitive functions, but not autistic traits, are related to TL in parents of children with ASD. Cognitive function and TL were not related in children and adolescents. As the third replication, our results elicit confidence in the finding that ASD is associated with shorter TL. Our novel sensory investigation suggests that shortened TL may be a biological mechanism of sensory symptoms in ASD. Furthermore, results highlight the need to better understand relationships between cognition, aging, and TL in families with ASD. Autism Res 2020, 13: 1094-1101. © 2020 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: Telomeres cap chromosomes to protect DNA. They progressively shorten as people age and are related to health outcomes. We replicated previous findings that children and adolescents with autism spectrum disorder (ASD) have shorter telomeres, compared to typically developing (TD), and show that unaffected siblings have telomere length (TL) in between those of TD and ASD. We find shortened TL is related to more severe sensory symptoms. This may mean families with ASD, especially those with elevated sensory symptoms, are at risk for worse age-related health outcomes.