ABSTRACT
The sex chromosomes, X and Y, are discussed. Each chromosome is illustrated with the mental health–related genes located. The X-linked disorders, i.e. Turner syndrome, Klinefelter syndrome, superwoman syndrome and fragile X syndrome are all explained in terms of chromosome counts, pathophysiology, signs and symptoms. The Y chromosome is discussed with reference to the SRY gene. The concepts of immediate early genes and late response genes are explained. The epigenome (epigenetics) and genetic imprinting inheritance are explained, with imprinting disorders Prader-Willi and Angelman syndromes discussed. The pathophysiology of the lissencephalic disorders (types I and II), including Walker-Warburg syndrome, is identified and discussed.
