Loss of Chromosome Y in Leukocytes and Major Cardiovascular Events

Sex differences in neuroimmunoendocrine communication. Involvement on longevity

Endocrine, nervous, and immune systems work coordinately to maintain the global homeostasis of the organism. They show sex differences in their functions that, in turn, contribute to sex differences beyond reproductive function. Females display a better control of the energetic metabolism and improved neuroprotection and have more antioxidant defenses and a better inflammatory status than males, which is associated with a more robust immune response than that of males. These differences are present from the early stages of life, being more relevant in adulthood and influencing the aging trajectory in each sex and may contribute to the different life lifespan between sexes.

Mosaic chromosome Y loss is associated with alterations in blood cell counts in UK Biobank men

Mosaic loss of Y chromosome (mLOY) is the most frequently detected somatic copy number alteration in leukocytes of men. In this study, we investigate blood cell counts as a potential mechanism linking mLOY to disease risk in 206,353 UK males. Associations between mLOY, detected by genotyping arrays, and blood cell counts were assessed by multivariable linear models adjusted for relevant risk factors. Among the participants, mLOY was detected in 39,809 men. We observed associations between mLOY and reduced erythrocyte count (−0.009 [−0.014, −0.005] × 10¹² cells/L, p = 2.75 × 10⁻⁵) and elevated thrombocyte count (5.523 [4.862, 6.183] × 10⁹ cells/L, p = 2.32 × 10⁻⁶⁰) and leukocyte count (0.218 [0.198, 0.239] × 10⁹ cells/L, p = 9.22 × 10⁻⁹⁵), particularly for neutrophil count (0.174 × [0.158, 0.190]10⁹ cells/L, p = 1.24 × 10⁻⁹⁹) and monocyte count (0.021 [0.018 to 0.024] × 10⁹ cells/L, p = 6.93 × 10⁻⁵⁷), but lymphocyte count was less consistent (0.016 [0.007, 0.025] × 10⁹ cells/L, p = 8.52 × 10⁻⁴). Stratified analyses indicate these associations are independent of the effects of aging and smoking. Our findings provide population-based evidence for associations between mLOY and blood cell counts that should stimulate investigation of the underlying biological mechanisms linking mLOY to cancer and chronic disease risk.

Mosaic Y Loss Is Moderately Associated with Solid Tumor Risk

Mosaic loss of the Y chromosome (mLOY) in peripheral leukocytes is a somatic event in which a fraction of leukocytes have lost the entire Y chromosome. The frequency of mLOY increases with age and may reflect poor genomic maintenance as well as clonal imbalances in normal immune function, making mLOY an attractive candidate marker for cancer risk. Here, we investigated the relationship between mLOY and incident cancer in a large sample of 207,603 cancer-free men from the UK Biobank, in which 13,895 men developed an incident solid tumor during follow-up. We identified mLOY by scanning for deviations in genotyping array log R intensity ratios across the male-specific chromosome Y region. Overall, we detected low proportions of cells with mLOY in 3,358 (1.6%) men and high proportions of mLOY in 524 (0.3%) men. We found an association of mLOY with overall solid tumor incidence using both low and high mLOY thresholds [HR_low = 1.18; 95% confidence interval (CI)_low, 1.07-1.30; P _low = 0.001; HR_high = 1.36; 95% CI_high, 1.09-1.71; P _high = 0.007] and more specifically we observed an association with lung cancer (HR_high = 2.25; 95% CI_high, 1.36-3.71; P _high = 0.002). Stronger associations were observed without adjustment for smoking, suggesting that smoking is an important confounder of tumor incidence. It is unlikely that mLOY is a major mediator of the effect of cigarette smoking on cancer risk, as mLOY was observed in only a small fraction of smokers who developed cancer. In summary, mLOY was modestly associated with incidence of solid tumors in the UK Biobank, although for some cancer subtypes these findings may reflect residual confounding by smoking. SIGNIFICANCE: Evidence from the UK Biobank indicates mosaic chromosome Y loss in leukocytes is moderately associated with increased incidence of select solid tumors.

Predictors of mosaic chromosome Y loss and associations with mortality in the UK Biobank

Mosaic loss of the Y chromosome (mLOY) is the most commonly reported large structural somatic event. Previous studies have indicated age and cigarette smoking increase the risk of mLOY, but the relationship of other exposures with mLOY and mLOY with disease has not been adequately investigated. We characterized mLOY in a large cohort of 223,338 men from the UK Biobank by scanning for deviations in genotyping array median log₂ intensity ratios (mLRR) of the Y chromosome using a standard algorithm. A total of 3,789 (1.7%) men showed evidence for mLOY (mLRR < −0.15). In multivariable-adjusted logistic regression models, we found that mLOY increases exponentially with age (overall P-value < 4.9 × 10⁻³²⁴; p-value for the quadratic term = 2.1 × 10⁻⁷), and observed a strong association with current smoking (P-value = 7.8 × 10⁻¹⁸⁴). We observed less mLOY in men of African ancestry (0.4%) compared to men of European ancestry (1.8%, P-value = 0.003). Although mLOY was not associated with prevalent cancer (P-value = 0.61), associations were observed for diabetes (P-value = 0.003) and cardiovascular disease (P-value = 0.01). Using Cox proportional hazards regression models, mLOY was associated with all-cause mortality among men with a high proportion of cells affected (mLRR < −0.40; HR = 1.35, 95% CI = 1.08–1.70, P-value = 0.009). In conclusion, mLOY was associated with several health-related factors as well as with all-cause mortality. Further functional studies are warranted to understand how and in what way mLOY could influence adult male health.