The shortening of telomeres with ageing is a well-documented observation; however, the reported number of
nucleotides in telomeres varies between different laboratories and studies. Such variability is likely caused by ethnic differences
between the populations studied. Until now, there were no studies that investigated the variability of telomere
length in a senescent Latvian population of the most common mitochondrial haplogroups, defined as H (45%), U (25%),
Y chromosomal N1c (40%) and R1a1 (40%). Telomere length was determined in 121 individuals in different age groups,
including a control group containing individuals of 20-40 years old and groups of individuals between 60-70 years old,
71-80 years old, 81-90 years old, and above 90 years old. Telomere length was determined using the Southern blot telomeric
restriction fragment assay (TRF). Decreased telomere length with ageing was confirmed, but a comparison of centenarians
and individuals between 60-90 years of age did not demonstrate a significant difference in telomere length.
However, significant variability in telomere length was observed in the control group, indicating probable rapid telomere
shortening in some individuals that could lead up to development of health status decline appearing with ageing. Telomere
length measured in mononuclear blood cells (MNC) was compared with the telomere length measured in whole peripheral
white blood cells (WBC) using TRF. Telomere length in MNC was longer than in WBC for the control group with individuals
20 to 40 years old; in contrast, for the group of individuals aged 65 to 85 years old, measured telomere length was
shorter in MNC when compared to WBC.