title: Variable number of tandem repeats polymorphism in parathyroid hormone-related protein as predictor of peak bone mass in young healthy Finnish males.
abstract: OBJECTIVE
  Mice with osteoblast-specific deletion of parathyroid hormone-related protein (PTHrP) exhibit impaired recruitment and increased apoptosis of osteogenic cells resulting in decreased bone formation and premature osteoporosis. The PTHrP levels within the bone microenvironment are therefore critical in influencing bone mass acquisition. Whether this is applicable in humans has not been established. Here, we studied the association of a variable number of tandem repeats (VNTR) polymorphism in PTHrP with peak bone mass.
  
  
  METHODS
  Enrolled in the study were 234 young Finnish males, with median age of 19.6 years (range 18.3-20.6 years). Lifestyle factors, serum bone markers, osteodensitometric measurements (lumbar spine and hip) and calcaneal quantitative ultrasound readings were obtained. The PTHrP VNTR length was determined by the PCR amplification of genomic DNA extracted from peripheral blood and correlated to bone parameters by the multiple regression models.
  
  
  RESULTS
  The presence of at least one 252 bp allele was associated with increased lumbar spine bone mineral density (BMD; P<0.0034), broadband ultrasound attenuation (BUA; P<0.0012) and speed-of-sound (SOS; P<0.0023) measurements. The correlation with increased lumbar spine BMD (P=0.0008), BUA (P=0.005) and SOS (P=0.001) was further strengthened by the pairing of the 252 bp allele with a 460 bp allele in comparison with those without any 252 bp allele. Electrophoretic mobility shift assays were used to illustrate the potential transcriptional functionality of the VNTR sequence.
  
  
  CONCLUSIONS
  The results indicate that the PTHrP VNTR sequence likely modulates local PTHrP expression within the skeletal microenvironment and could serve as a diagnostic predictor of peak bone mass acquisition.
authors.affiliation: Osta Biotechnologies Inc., Pointe Claire, Québec, H9A 3H2 Canada.
authors.forename: Ajay
authors.initials: A
authors.lastname: Gupta
authors.forename: Ville-Valtteri
authors.initials: VV
authors.lastname: Välimäki
authors.forename: Matti
authors.initials: M
authors.lastname: J Välimäki
authors.forename: Eliisa
authors.initials: E
authors.lastname: Löyttyniemi
authors.forename: Marilyn
authors.initials: M
authors.lastname: Richard
authors.forename: Prasanna
authors.initials: P
authors.lastname: L Bukka
authors.forename: David
authors.initials: D
authors.lastname: Goltzman
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Karaplis
mesh_terms: D000293:Adolescent; D000328:Adult; D000483:Alleles; D000818:Animals; D001483:Base Sequence; D015519:Bone Density / Q000235:genetics*; D019556:COS Cells; D002522:Chlorocebus aethiops; D005387:Finland; D014644:Genetic Variation; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging; D008297:Male; D008969:Molecular Sequence Data; D010006:Osteoblasts / Q000166:cytology / Q000502:physiology; D010024:Osteoporosis / Q000453:epidemiology / Q000235:genetics*; D044162:Parathyroid Hormone-Related Protein / Q000235:genetics*; D011110:Polymorphism, Genetic; D011237:Predictive Value of Tests; D012307:Risk Factors; D020080:Tandem Repeat Sequences; D014463:Ultrasonography
chemical_list: D044162:Parathyroid Hormone-Related Protein