Genetically determined phenotype covariation networks control bone strength

Karl J. Jepsen, Hayden William Courtland, Joseph H. Nadeau

Research output: Contribution to journalArticlepeer-review

25 Scopus citations

Abstract

To identify genes affecting bone strength, we studied how genetic variants regulate components of a phenotypic covariation network that was previously shown to accurately characterize the compensatory trait interactions involved in functional adaptation during growth. Quantitative trait loci (QTLs) regulating femoral robustness, morphologic compensation, and mineralization (tissue quality) were mapped at three ages during growth using AXB/BXA Recombinant Inbred (RI) mouse strains and adult B6-iA Chromosome Substitution Strains (CSS). QTLs for robustness were identified on chromosomes 8, 12, 18, and 19 and confirmed at all three ages, indicating that genetic variants established robustness postnatally without further modification. A QTL for morphologic compensation, which was measured as the relationship between cortical area and body weight, was identified on chromosome 8. This QTL limited the amount of bone formed during growth and thus acted as a setpoint for diaphyseal bone mass. Additional QTLs were identified from the CSS analysis. QTLs for robustness and morphologic compensation regulated bone structure independently (ie, in a nonpleiotropic manner), indicating that each trait may be targeted separately to individualize treatments aiming to improve strength. Multiple regression analyses showed that variation in morphologic compensation and tissue quality, not bone size, determined femoral strength relative to body weight. Thus an individual inheriting slender bones will not necessarily inherit weak bones unless the individual also inherits a gene that impairs compensation. This systems genetic analysis showed that genetically determined phenotype covariation networks control bone strength, suggesting that incorporating functional adaptation into genetic analyses will advance our understanding of the genetic basis of bone strength.

Original languageEnglish
Pages (from-to)1581-1593
Number of pages13
JournalJournal of Bone and Mineral Research
Volume25
Issue number7
DOIs
StatePublished - Jul 2010

Keywords

  • Biomechanics
  • Bone
  • Chromosome substitution strains
  • Growth
  • Morphology
  • Phenotypic covariation
  • QTL
  • Recombinant inbred mouse strains
  • Strength
  • Systems genetics

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