Table I.

Effect of demographic characteristics and hTERT genotype on mean TL in peripheral lymphocytes of study subjects

Variable	Number of subjects	TL (kb)a (group mean ± SD)
All	56	6.0 ± 1.0
Age (years)
≤56b	23	6.5 ± 1.0
>56	33	5.7 ± 0.9**
Gender
Males	25	5.9 ± 1.0
Females	31	6.1 ± 1.0
Smoking habits
Current	9	6.4 ± 0.6
Ex/never-smokers	47	5.9 ± 1.1
hTERT genotype
TT	18	6.2 ± 1.2
TC	28	6.0 ± 0.7
CC	10	5.5 ± 1.4

^aTL, individual mean telomere length, as determined by TRF analysis (see Methods).

^bMean population age.

**P value = 0.005 (non-parametric Mann–Whitney U test).