Accumulating evidence suggests that nearly all human diseases have sex-specific differences in prevalence, age of onset, and/or severity. Classic examples include the predominance of men with cardiovascular disease throughout adult life but a higher rate of occurrence in post-menopausal women compared to men6, the higher prevalence of asthma among boys in childhood and higher occurrence of new cases among girls around and following puberty7, and the increased prevalence of autoimmune diseases in women throughout life but particularly for diseases that onset during or immediately following the reproductive years8 (Figure 3). In addition to those diseases highlighted in Figure 3, significant sex differences have been described for many common birth defects, neurological and psychiatric disorders, as well as for some common cancers. For example, in infancy or childhood, neural tube defects, congenital dislocation of the hip, and scoliosis are more common among girls whereas autism, stuttering, and pyloric stenosis are more common among boys9. In adulthood, major depression and Alzheimer disease are more common in women10,11 whereas schizophrenia, Parkinson disease, and colorectal cancer are more common in men12-14.
