Sex-related differences in length and erosion dynamics of human telomeres favor females.

Telomeres are repetitive DNA sequences at chromosomal ends contributing to genomic integrity. In somatic cells, telomeres are shortened during DNA reduplication. Thus, telomere erosion has been regarded as a biological clock. Applying the telomere/centromere (T/C)-FISH technique to human peripheral blood lymphocytes, we showed that pangenomically, telomere shortening is linear in centenarians and that this attrition is delayed in females. Statistics reveal a greater skewness in telomere length distribution in females. As the morphological correlate, we find abnormally long telomeres distributed at random. This "erratic extensive elongation" (EEE) of telomeres is a hitherto unrecognized phenomenon in non-neoplastic cells, and females are more successful in this respect. As evidenced by endoreduplication, EEE is transmitted to the cells' progeny. The mechanism involved is likely to be the alternative pathway of telomere elongation (ALT), counteracting erosion and already known to operate in neoplastic cells.