Early puberty could increase a girl's chance of diabetes, heart disease and breast cancer, scientists warn

The age at which a girl reaches puberty could affect her risk of developing diabetes, heart disease and breast cancer later in life, scientists believe.
A new study carried out at the University of Cambridge has found the age at which a girl reaches sexual maturity is determined by which parent they inherit specific genes from.
Imprinted genes are a set inherited from just one parent, and as such their activity differs depending on which parent passes the gene on.
And the discovery could pave the way for genetic studies into the links between puberty and the likelihood of developing a range of disease later in life, the researchers said.
Dr John Perry at the Medical Research Council (MRC) epidemiology unit at Cambridge said: '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.'

'We knew that some imprinted genes control antenatal growth and development - but there is increasing interest in the possibility that imprinted genes may also control childhood maturation and later life outcomes, including disease risks.'
The discovery was made by studying more than 180,000 women and their DNA to find out which genetic variations determined when a girl reaches sexual maturity.
Researchers identified 123 genetic variations that were associated with the timing of when girls experienced their first menstrual cycle. Six of these variants were found to be clustered within imprinted regions of the genome.

 

The study published in the journal Nature found 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.

Senior author and paediatrician Dr Ken Ong at the MRC epidemiology unit said scientists could use the study into imprinted genes to find out how they might affect a girl’s development in later life.

'There is a remarkably wide diversity in puberty timing - some girls start at age 8 and others at 13, Dr Ong said.
'While lifestyle factors such as nutrition and physical activity do play a role, our findings reveal a wide and complex network of genetic factors.
'We are studying these factors to understand how early puberty in girls is linked to higher risks of developing diabetes, heart disease and breast cancer in later life - and to hopefully one day break this link,' he said.
Dr Anna Murray, a co-author from the University of Exeter Medical School, added: 'We found that there are hundreds of genes involved in puberty timing, including 29 involved in the production and functioning of hormones, which has increased our knowledge of the biological processes that are involved, in both girls and boys.'