Women who had not conceived naturally showed significantly higher levels of blood cells missing one X chromosome than women who had, according to a study led by Associate Professor Takuya Misugi and Professor Daisuke Tachibana at Osaka Metropolitan University's Graduate School of Medicine. The team extracted white blood cells from women aged 20 to 45 - 123 who had conceived naturally and 381 who had not - and compared rates of what geneticists call loss of the X chromosome, or LOX. Once LOX cells exceeded roughly 0.9 percent of white blood cells, the likelihood of natural pregnancy dropped.
The finding is of interest to readers following dementia research because of LOX's male counterpart. With age, men can lose the Y chromosome from some of their cells, and that loss of the Y chromosome, or LOY, has been associated with Alzheimer's disease, diabetes and heart disease. LOX, by contrast, has been tied mainly to acute myeloid leukemia and pneumonia, and its effects on reproduction had barely been examined. Both phenomena describe the same underlying process: cells accumulating chromosomal losses over a lifetime, with consequences that appear to reach well beyond the tissues where the loss is measured.
The researchers also compared LOX with anti-Mullerian hormone, a standard marker of ovarian reserve, and found no association between the two. That independence is the practical point. If LOX carries information AMH does not, the two measures used together could sharpen predictions about whether natural conception is realistic. The authors suggest that measuring LOX in people experiencing infertility might eventually help clarify whether to pursue treatments such as in vitro fertilization sooner rather than later.
This was an observational comparison in a single group of women, so it establishes an association rather than a cause, and the 0.9 percent figure is a first estimate rather than a clinical cutoff. Still, the study adds to a growing line of work suggesting that age-related loss of sex chromosomes in blood cells is a measurable marker of biological aging with links to conditions ranging from infertility to neurodegeneration.