The oestrogen receptor α gene is linked and/or associated with age of menarche in different ethnic groups

he first menstrual period, menarche, is one of the most significant milestones in a woman’s life. The age at menarche is an important anthropological variable which may influence the overall duration of tissue oestrogen exposure and then affect health in later life. Early menarche is a well established risk factor for the development of breast cancer 1 and endometrial cancer. 2 Women with a menarcheal age of 10 or 11 years have a 2.2 times greater risk of breast cancer than women who had their first menstrual period at the age of 12 years or more. 1 Those with a menarcheal age of 17 years or more have a 45% lower risk of endometrial cancer. 2 Early age at menarche is also associated with a risk for obesity 3 and depression in later life. 4 On the other hand, late menarche is associated with lower bone mass and an increased risk of osteoporotic fractures 5 and Alzheimer’s disease. 6 Therefore an understanding of potential factors responsible for the age of menarche is of considerable interest and may shed light on our understanding of these diseases. Age at menarche is a complex trait that is determined by multiple environmental factors, including nutrition, exercise, socioeconomic conditions, psychosocial stimuli, childhood experience, general health, 6–10