special subjects
Factors Affecting Gene Expression
Sex limited inheritance
A trait that appears in only one sex is called sex-limited. Sex-limited inheritance is distinct from X-linked inheritance, which refers to traits carried on the X chromosome. Sex-limited inheritance, perhaps more correctly called sex-influenced inheritance, refers to special cases in which sex hormones and other physiologic differences between males and females alter the expressivity and penetrance of a gene. For example, premature baldness (known as male-pattern baldness) is an autosomal dominant trait, but such baldness is rarely expressed in females and then usually only after menopause. 