title: Lack of association between leukocyte telomere length and genetic variants in two ageing-related candidate genes.
abstract: BACKGROUND
  Leukocyte telomere length, a putative marker of ageing, is a highly variable and heritable complex trait. In order to determine the possible underlying genetic variants for leukocyte telomere length variation, we conducted an association study of leukocyte telomere length and two candidate genes for ageing-related traits, TGFB1 and KLOTHO, in a female Caucasian dizygotic twin population.
  
  
  METHODS
  Terminal restriction fragment (TRF) length, an index of telomere length, was measured using Southern Blotting. Six and four single nucleotide polymorphisms (SNP) were genotyped in TGFB1 and KLOTHO gene, respectively, and tested for association. When there is strong LD between SNPs (r(2) > 0.5), haplotypic association was investigated using haplotype trend regression approach.
  
  
  RESULTS
  All SNPs were in Hardy-Weinberg equilibrium (p > 0.05). No significant association was detected for individual SNPs (p > 0.101), or two-locus haplotypes (p = 0.7497) with TRF variation.
  
  
  CONCLUSIONS
  We failed to find any significant association between leukocyte telomere length and 10 SNPs in two ageing-related candidate genes, TGFB1 and KLOTHO. This result suggests that while we could not exclude minor effects, none of 10 SNPs in these two candidate genes showed significant association with the variation of leukocyte telomere length in our cohort. But as it is unclear whether telomere length dynamics is the cause or the effect of the ageing process, it is still possible the genes are associated with ageing via alternate mechanisms.
authors.affiliation: Twin Research and Genetic Epidemiology Unit, St. Thomas' Hospital, King's College London, United Kingdom. feng.zhang@kcl.ac.uk
authors.forename: Feng
authors.initials: F
authors.lastname: Zhang
authors.forename: Bernet S
authors.initials: BS
authors.lastname: Kato
authors.forename: Jeffery P
authors.initials: JP
authors.lastname: Gardner
authors.forename: Masayuki
authors.initials: M
authors.lastname: Kimura
authors.forename: Tim D
authors.initials: TD
authors.lastname: Spector
authors.forename: Kourosh R
authors.initials: KR
authors.lastname: Ahmadi
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging / Q000235:genetics*; D005260:Female; D014644:Genetic Variation; D005966:Glucuronidase / Q000235:genetics*; D006239:Haplotypes; D006801:Humans; D000090265:Klotho Proteins; D007962:Leukocytes / Q000502:physiology; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide; D016615:Telomere / Q000502:physiology*; D053773:Transforming Growth Factor beta1 / Q000235:genetics*; D014429:Twins, Dizygotic; D044465:White People / Q000235:genetics
chemical_list: D053773:Transforming Growth Factor beta1; D005966:Glucuronidase; D000090265:Klotho Proteins