Incidence, prevalence, age at diagnosis, and mortality in individuals with 45,X/46,XY mosaicism: A population-based registry study

Purpose: To assess the population-based incidence, prevalence, and age at diagnosis of individuals with 45,X/46,XY mosaicism (and associated variants) and describe the associated mortality pattern. In addition, a systematic literature review of papers providing prevalence data of 45,X/46,XY mosaicism was performed.Methods: A population-based epidemiological study of all individuals diagnosed with 45,X/ 46,XY mosaicism between 1960 and 2019. Mortality was analyzed using data from the Danish Causes of Death Register. One-hundred randomly age-and sex-matched general population controls per case were identified for comparison.Results: One-hundred-thirty-seven males and 46 females with 45,X/46,XY mosaicism were identified. The apparent prevalence was 5.6 per 100,000 liveborn males and 2.1 per 100,000 liveborn females. The incidence of males with 45,X/46,XY increased during the study (P > .0001) but was stable for females (P = .4). Males were significantly older than females when diagnosed (median age = 29.1, interquartile range: 3.4-41.3) years versus 13.3 (interquartile range: 2.1-19.1) years, P = .002). All-cause mortality was doubled in males with 45,X/46,XY (Hazard Ratio = 2.0, 95% confidence interval: 1.2-3.3) and quadrupled in females (Hazard Ratio = 4.0, confidence interval: 2.0-7.9).Conclusion: The apparent population-based prevalence of males and females with 45,X/46,XY is 5.6 and 2.1 per 100,000 liveborn males and females, respectively. Diagnosis of males with 45,X/46,XY males is increasing. 45,X/46,XY mosaicism is associated with an increased all-cause mortality.(c) 2023 The Authors. Published by Elsevier Inc. on behalf of American College of Medical Genetics and Genomics. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).