Determination of the obesity-associated gene variants within the entire FTO gene by ultra-deep targeted sequencing in obese and lean children

Background: The Fat mass and obesity-associated gene ( FTO ) was the first gene reliably associated with body mass index in genome-wide association studies on a population level. At present, the genetic variations within the FTO gene are still the common variants that have the largest influence on body mass index. Methods: In the current study, we amplified the entire FTO gene, in total 412 Kbp, in over 200 long-range PCR fragments from each individual, from 524 severely obese and 527 lean Swedish children, and sequenced the products as two DNA pools using massive parallel sequencing (SOLiD). Results: The sequencing achieved very high coverage (median 18 000 reads) and we detected and estimated allele frequencies for 705 single nucleotide polymorphisms (SNPs) (19 novel) and 40 indels (24 novel) using a sophisticated statistical approach to remove false-positive SNPs. We identified 19 obesity-associated SNPs within intron one of the FTO gene, and validated our findings with genotyping. Ten of the validated obesity-associated SNPs have a stronger obesity association ( P