Table 2.
Results for telomere length and sperm parameters.
| Studies | Samples | Method of Telomere Measurement | Results—Main Findings | p |
|---|---|---|---|---|
| Ferlin et al., 2013 [21] | Sperm et leukocytes | qPCR | Significant positive correlation between STL and sperm count: rS = 0.33 | 0.0029 * |
| No significant positive correlation between LTL and sperm count: rS = 0.003 | 0.9780 | |||
| Oligozoospermic men: STL = 0.95 ± 0.22 | 0.0001 * | |||
| Normozoospermic men: STL = 1.24 ± 0.25 | ||||
| No difference was observed in LTL between the 2 groups | ||||
| Turner et al., 2013 [23] | Sperm | Q-FISH | No association between semen parameters or male fertility and STL | >0.05 |
| Antunes et al., 2015 [24] | Sperm | qPCR | Normal semen parameters: STL = 16.63 ± 22.29 | 0.0001 * |
| Abnormal semen parameters: STL = 6.92 ± 18.13 | ||||
| Morphologically normal spermatozoa: STL = 12.40 ± 19.77 | 0.991 | |||
| Morphologically abnormal spermatozoa: STL = 13.11 ± 22.56 | ||||
| Yang et al., 2015 [26] | Sperm | qPCR | Significant positive correlation between STL and total sperm number: rp = 0.53 | <0.01 * |
| Yang et al., 2015 [25] | Sperm | qPCR | Significant correlation between STL and sperm count: rp= 0.28 | 0.001 * |
| Cariati et al., 2016 [27] | Sperm | qPCR | Normozoospermic group: STL = 1.4 ± 0.1 | 0.0024 * |
| Oligozoospermic group: STL = 0.9 ± 0.1 | ||||
| Significant positive correlation between STL and sperm count: r = 0.325 | 0.006 * | |||
| Rocca et al., 2016 [29] | Sperm | qPCR | STL is positively associated with: | |
| Progressive motility rp = 0.46 | 0.004 * | |||
| Sperm vitality rp = 0.340 | 0.007 * | |||
| Heidary et al., 2018 [31] | Leukocytes | qPCR | Azoospermic men: LTL = 0.54 Fertile men: LTL = 0.84 | <0.05 * |
| Lafuente et al., 2018 [32] | Sperm | Q-FISH | Significant positive correlations between: | |
| STL and sperm concentration: r = −0.308 | 0.049 * | |||
| STL and progressive motility: r = −0.353 | 0.028 * | |||
| STL and immotile sperm: r = 0.446 | 0.007 * | |||
| No significant correlation between STL and sperm DNA fragmentation | >0.05 | |||
| Torra-Massana et al., 2018 [13] | Sperm | qPCR | No relevant correlation between STL and sperm motility | 0.34 |
| Significant correlation between STL and sperm concentration | 0.03 * | |||
| Yang et al., 2018 [33] | Leukocytes | qPCR | Controls + OA: LTL = 0.96; NOA: LTL = 0,81 [OR 0.172; 95% CI 0.107–0.279] No significant difference between OA and normozoospermic controls | <0.001 * |
| Lopes et al., 2020 [37] | Selected sperm | qPCR | No relation between STL and total sperm count | 0.590 |
| No relation between STL and sperm motility | 0.354 | |||
| No relation between STL and normal morphology | 0.169 | |||
| Amirzadegan et al., 2021 [38] | Leukocytes and sperm | qPCR | Oligozoospermic men: LTL = 0.61 ± 0.30 | 0.01 * |
| Fertile men: LTL = 1.22 ± 0.71 | ||||
| Oligozoospermic men: STL = 0.65 ± 0.25 | 0.02 * | |||
| Fertile men: STL = 1.04 ± 0.46 | ||||
| Gentiluomo et al., 2021 [39] | Sperm | qPCR | No significant association between STL and sperm parameters | >0.05 |
| Balmori et al., 2022 [41] | Sperm and PBMC | Q-FISH | In NZ ≤ 25 years, significant positive correlation between STL and | |
| Sperm count: r = 0.641 | 0.009 * | |||
| Motility: r = 0.639 | 0.007 * | |||
| OAZ men ≤ 25 years: TL shorter than NZ men ≤ 25 years; NZ men ≥ 40 years; | 0.0081 * | |||
| OAZ men ≥ 40 years | 0.0116 * | |||
| 0.009 * |
PBMC, peripheral blood mononuclear cells. Results are expressed as mean STL ± standard deviation of the mean. STL determined by a qPCR-based method could be expressed as absolute or relative mean telomere length or correlation coefficient. * p values < 0.05 are significant.