Shorter Telomeres and Faster Telomere Attrition in Individuals With Five Syndromic Forms of Intellectual Disability: A Systematic Review and Meta-Analysis.

Heterogeneity was very high (I² = 95%), meaning the individual studies disagreed substantially and the pooled estimate is uncertain. The funnel plot suggested possible publication bias, with 11 of 15 studies deviating from the centre. Individual studies were small; some had as few as 4 or 5 participants per group. The rate of telomere shortening was estimated by linear regression across age groups, not by measuring the same cells over time. Telomere length is reported as a mean across all chromosomes; the shortest telomeres, which drive cellular senescence, were not measured in most studies. Data could not be obtained from all eligible studies; some were included using digitised values from published figures. The severity of intellectual disability within each syndrome was not reported. Biological sex was unclear in the majority of included studies. Only five specific genetic syndromes are represented; the findings cannot be extended to all intellectual disability.

The authors declare no conflicts of interest.

Do not read the pooled result as a uniform finding across all intellectual disability. The five syndromes have different genetic causes, the Down syndrome subgroup did not reach significance, and heterogeneity was very high. This is a cellular measurement in specific genetic conditions, not evidence that any treatment works or that all people with intellectual disability age faster at the cellular level.