Reykjavik, ICELAND, May 17 /PRNewswire-FirstCall/ -- In a paper published today in the online edition of Nature Genetics, scientists from deCODE genetics (Nasdaq:DCGN) and academic colleagues from Iceland, Denmark and the Netherlands present the discovery of single letter variations in the sequence of the human genome (SNPs) that influence the age of girls at menarche, the first menstrual period. Age at menarche (AAM) is influenced by both genetic and environmental factors, though the SNPs reported today are the first genetic factors to be found. AAM is of interest not only because it heralds the beginning of a woman's reproductive life, but because it is also linked with susceptibility to disease later in life. Obesity in particular is linked to earlier AAM, and earlier AAM is in turn associated with risk of breast, ovarian and endometrial cancers. Later AAM increases risk of osteporosis.

Through the analysis of more than 300,000 SNPs across the genomes of more than 15,000 Icelandic women, and confirmed through genotypic analysis of some 10,000 Danish and Dutch women, the deCODE team identified two common SNPs on chromosome 6q21 that are associated with between one and two months later AAM per copy carried. This was encouraging, as last year deCODE had linked the same SNPs to greater adult height, and increased aldult height has been shown to correlate with later AAM. Indeed, looking at height measurements from 38,000 Icelandic women, those carrying these SNPs were 0.3 cm taller per copy carried.

Furthermore it appears that it is AAM that is having the impact on height, and not the other way around. This is in keeping with the fact that the 6q21 variants also confer greater adult height in men, and also suggests that these SNPs should be involved in the onset of puberty in boys as well. The deCODE team also demonstrated that several known genetic variants linked to overweight and obesity also correlated with earlier AAM.

'The findings presented today are evidence of how our approach of bringing together vast amounts of genetic and health information can shed light on the processes driving complex human traits. These SNPs offer a first step toward understanding the genetic component of AAM, and probably the timing of the onset of puberty in boys as well. But we have also been able to use them to confirm that overweight and obesity is linked to earlier AAM, and to suggest that later AAM contributes to greater height.