Epigenetic age acceleration in Turner and Klinefelter syndrome: Correlations with clinical aging markers.

Background: The sex chromosome aneuploidies Turner syndrome (45,X; TS) and Klinefelter syndrome (47,XXY; KS) are associated with aging-related comorbidities, reduced life expectancy and genome-wide DNA methylation changes. This indicates that biological aging, reflecting physiological function rather than chronological age, is increased in both syndromes. To investigate whether DNA methylation patterns linked to physiological decline could contribute to the comorbidity patterns and reduced lifespan in TS and KS, we applied so-called epigenetic clocks to DNA methylation data from cohorts of TS (n = 57) compared to female controls (n = 33) and KS (n = 65) compared to male controls (n = 63).