Age of Puberty in Girls Influenced by Which Parent Passes on Genes.

The age at which girls reach sexual maturity is influenced by imprinted genes, a small subset of genes with differing activity depending on which parent passes them on, according to new research published in the journal Nature.

The findings come from an international study of more than 180,000 women involving scientists from 166 institutions worldwide, including the Boston University schools of public health and medicine. The researchers identified 123 genetic variations that were associated with the timing of when girls experienced their first menstrual cycle by analyzing the DNA of 182,416 women of European descent from 57 studies. Six of the variants were found to be clustered within imprinted regions of the genome.

The activity of imprinted genes differs depending on which parent the gene is inherited from. Some genes are only active when inherited from the mother; others are only active when inherited from the father. Both types of imprinted genes were identified as determining puberty timing in girls, indicating a possible biological conflict between the parents over their child’s rate of development.

Further evidence for the parental imbalance in inheritance patterns was obtained by analyzing the association between these imprinted genes and timing of puberty in a study of over 35,000 women in Iceland, for whom detailed information on their family trees was available.

This is the first time that it has been shown that imprinted genes can control the rate of development after birth. Kathryn Lunetta, a biostatistics professor at the BU School of Public Health, was a co-author.

Senior author Dr Joanne Murabito of the BU School of Medicine and Framingham Heart Study, said the findings “demonstrate a complex network of genetic factors underlying the timing of menarche. Menarche is associated with the development of health conditions later in life in women, such as diabetes, cardiovascular disease, and breast cancer. By studying genetic factors, we hope to better understand how puberty timing in girls is linked to important health conditions in women.”