The age at which girls reach sexual maturity is influenced by ‘imprinted’ genes, a small sub-set of genes whose activity differs depending on which parent passes on that gene, according to new research published today 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 University of Cambridge. The researchers identified 123 genetic variations that were associated with the timing of when girls experienced their first menstrual cycle by analysing the DNA of 182,416 women of European descent from 57 studies. Six of these variants were found to be clustered within imprinted regions of the genome.
Lead author Dr John Perry at the Medical Research Council (MRC) Epidemiology Unit, University of Cambridge says: “Normally, our inherited physical characteristics reflect a roughly average combination of our parents’ genomes, but imprinted genes place unequal weight on the influence of either the mother’s or the father’s genes. Our findings imply that in a family, one parent may more profoundly affect puberty timing in their daughters than the other parent.”
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 analysing 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 were available.
Puberty timing varies from 8 to 13. This is said to be the first demonstration of a role for imprinted genes after birth, though some were known to control growth before birth.
While not strictly epigenetics, this is another example of the variability of the inheritance process (compared to how many researchers thought it worked decades ago).
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