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Steve Horvath is a UCLA professor known for developing the Horvath aging clock, which is a highly accurate molecular biomarker of aging, and for developing weighted correlation network analysis. The recipient of several research awards, including an Allen Distinguished Investigator award, he has studied genomic biomarkers of aging, the aging process, and many age related diseases/conditions.

Background
Horvath was born in Frankfurt, Germany. He received his Ph.D. in mathematics at the University of North Carolina in 1995 and his Sc.D. in biostatistics at Harvard in 2000. In 2000 Horvath joined the faculty of the University of California, Los Angeles, where he is a Professor of human genetics at the David Geffen School of Medicine at UCLA and of biostatistics at the UCLA Fielding School of Public Health.

Work on the epigenetic clock
Horvath's development of the DNA methylation based age estimation method known as epigenetic clock was featured in Nature magzine. In 2011 Horvath co-authored the first article that described an age estimation method based on DNA methylation levels from saliva. In 2013 Horvath published a single author article on a multi-tissue age estimation method that applies to call nucleated cells, tissues, and organs. This discovery, known as the Horvath clock, was unexpected because cell types differ in terms of the their DNA methylation patterns and age related DNA methylation changes tend to be tissue specific. In his article, he demonstrated that estimated age, also referred to as DNA methylation age, has the following properties: it is close to zero for embryonic and induced pluripotent stem cells, it correlates with cell passage number; it gives rise to a highly heritable measure of age acceleration; and it is applicable to chimpanzees. Since the Horvath clock allows one to contrast the ages of different tissues from the same individuals, it can be used to identify tissues that show evidence of accelerated age due to disease. Horvath co-authored the first articles demonstrating that DNAm age predicts life-expectancy  and is positively associated with obesity, HIV infection, Alzheimer's disease, Down syndrome, cognitive decline, Huntington's disease, early menopause, Werner syndrome. Using genome-wide association studies, his team identified the first genetic markers (SNPs) that exhibit genome-wide significant associations with epigenetic aging rates.

Weighted correlation network analysis
Horvath and members of his lab developed a widely used systems biological data mining technique known as weighted correlation network analysis. He published a book on weighted network analysis and genomic applications.