Scientists from the Medical Research Council have identified the first genetic variant associated with the start of puberty in humans. During puberty the body undergoes changes from childhood to adult including rapid growth and sexual maturation. The researchers performed a "genome wide association study", published in Nature Genetics, and found that a variation in the human gene "LIN28B" was associated with the age at which a girl starts her menstrual cycles. They went on to show that this genetic variation is associated with the timing of many other characteristics of early puberty in both girls and boys.

Lead author Dr Ken Ong of the MRC Epidemiology Unit, Cambridge says, "The LIN28B gene is closely related to a gene (lin-28) that controls the rate of maturation in the nematode worm, Caenorhabditis elegans. It is remarkable that the human system of growth and development appears to be the same as that in very primitive creatures like the nematode worm."

Genetic studies in thousands of volunteers from studies in the UK ( including the MRC National Survey of Health and Development) and other European countries showed that this genetic variation was associated with early breast development in girls. In boys, it was associated with early voice breaking and early growth of pubic hair. Both girls and boys with this genetic variant grew faster between the ages of 7 and 11 years, but adults with this variant were relatively short. These findings illustrate that many early developers are often tall children but become short adults because they stop growing early.

Dr Ken Ong says, "Early puberty is seen in some overweight and obese children. These important findings now allow us to study how genetic factors like LIN28B work together with diet and physical activity to influence the timing of growth and maturation in children."