Faculty Collaboration Database

Low bone strength is a manifestation of phenylketonuria in mice and is attenuated by a glycomacropeptide diet. PLoS One 2012;7(9):e45165

Date

10/03/2012

Pubmed ID

23028819

Pubmed Central ID

PMC3445501

DOI

10.1371/journal.pone.0045165

Scopus ID

2-s2.0-84866509174 (requires institutional sign-in at Scopus site)   54 Citations

Abstract

PURPOSE: Phenylketonuria (PKU), caused by phenylalanine (phe) hydroxylase loss of function mutations, requires a low-phe diet plus amino acid (AA) formula to prevent cognitive impairment. Glycomacropeptide (GMP), a low-phe whey protein, provides a palatable alternative to AA formula. Skeletal fragility is a poorly understood chronic complication of PKU. We sought to characterize the impact of the PKU genotype and dietary protein source on bone biomechanics.

PROCEDURES: Wild type (WT; Pah(+/+)) and PKU (Pah(enu2/enu2)) mice on a C57BL/6J background were fed high-phe casein, low-phe AA, and low-phe GMP diets between 3 to 23 weeks of age. Following euthanasia, femur biomechanics were assessed by 3-point bending and femoral diaphyseal structure was determined. Femoral ex vivo bone mineral density (BMD) was assessed by dual-energy x-ray absorptiometry. Whole bone parameters were used in principal component analysis. Data were analyzed by 3-way ANCOVA with genotype, sex, and diet as the main factors.

FINDINGS: Regardless of diet and sex, PKU femora were more brittle, as manifested by lower post-yield displacement, weaker, as manifested by lower energy and yield and maximal loads, and showed reduced BMD compared with WT femora. Four principal components accounted for 87% of the variance and all differed significantly by genotype. Regardless of genotype and sex, the AA diet reduced femoral cross-sectional area and consequent maximal load compared with the GMP diet.

CONCLUSIONS: Skeletal fragility, as reflected in brittle and weak femora, is an inherent feature of PKU. This PKU bone phenotype is attenuated by a GMP diet compared with an AA diet.

Author List

Solverson P, Murali SG, Litscher SJ, Blank RD, Ney DM

MESH terms used to index this publication - Major topics in bold

Absorptiometry, Photon
Animals
Biomechanical Phenomena
Bone Density
Caseins
Diet, Protein-Restricted
Elastic Modulus
Female
Femur
Male
Mice
Mice, Inbred C57BL
Mice, Transgenic
Peptide Fragments
Phenotype
Phenylalanine
Phenylalanine Hydroxylase
Phenylketonurias