Menarche, age at

Menarche refers to a female's first menstrual period or bleeding, and the 'age at menarche' is a oft-studied parameter potentially influencing subsequent health issues. The average age at menarche (AAM) in the US is about 12.5 years of age.Wikipedia

AAM is of interest because of a wide variety of correlations between it and various diseases as well as height, as well as for its reproductive significance. Linked to earlier AAM are obesity, and to some extent, higher risk for breast, ovarian and endometrial cancers. Linked to later AAM are increased height and also risk of osteoporosis.

Age at menarche shows reasonably high heritability, but the genetic variations influencing it are only just beginning to be elucidated. SNPs reported to be associated with earlier or later age at menarche include:

• SNPs in the SPOCK1 gene, including:
  • rs13357391
  • rs1859345

• SNPs from 2 chromosomal regions, reported by deCode:
  • rs2090409, ch 9q31.2
  • rs7759938, ch 6q21

23andMe blog

• rs7861820 C about five weeks earlier menarche.
• rs314276 or the equivalent rs314263(T) yields
  • menarche about six weeks earlier
  • 1.2x accelerated breast development and a faster rate of increase in height and weight.
  • a reduction in adult height of about 0.15 inches.