Clinical significance of low-frequency mosaic thresholds (45,X/46,XX/47,XXX) in adulthood: A case report

We present a distinction between age-related X chromosome loss and true mosaicism in women over 50 years of age and the clinical course in adulthood due to the low frequency of X chromosome dual aneuploidy. Clinical reports of adult women with the 45,X/46,XX/47,XXX karyotype are extremely rare. In a 51-year-old woman with short stature and schizophrenia with secondary amenorrhea shortly after the onset of her early menstrual period, the proportion of 45,X cell lines was 10 % by G-band and fluorescence in situ hybridization in the peripheral blood. The presence of 45,X in buccal mucosa cells and 47,XXX in peripheral blood suggests true mosaicism due to non-segregation in the early embryo rather than age-related X chromosome loss. This case supports the recent reports that a possible phenotypic effect exists at a 45,X cell threshold of 5 %.