Genetic modifiers of ambulation in the Cooperative International Neuromuscular Research Group Duchenne Natural History Study.

ABSTRACT: We studied the effects of LTBP4 and SPP1 polymorphisms on age at loss of ambulation (LoA) in a multiethnic Duchenne muscular dystrophy (DMD) cohort.We genotyped SPP1 rs28357094 and LTBP4 haplotype in 283 of 340 participants in the Cooperative International Neuromuscular Research Group Duchenne Natural History Study (CINRG-DNHS). Median ages at LoA were compared by Kaplan-Meier analysis and log-rank test. We controlled polymorphism analyses for concurrent effects of glucocorticoid corticosteroid (GC) treatment (time-varying Cox regression) and for population stratification (multidimensional scaling of genome-wide markers).Hispanic and South Asian participants (n?=?18, 41) lost ambulation 2.7 and 2 years earlier than Caucasian subjects (p?=?0.003, <0.001). The TG/GG genotype at SPP1 rs28357094 was associated to 1.2-year-earlier median LoA (p?=?0.048). This difference was greater (1.9 years, p?=?0.038) in GC-treated participants, whereas no difference was observed in untreated subjects. Cox regression confirmed a significant effect of SPP1 genotype in GC-treated participants (hazard ratio?=?1.61, p?=?0.016). LTBP4 genotype showed a direction of association with age at LoA as previously reported, but it was not statistically significant. After controlling for population stratification, we confirmed a strong effect of LTBP4 genotype in Caucasians (2.4 years, p?=?0.024). Median age at LoA with the protective LTBP4 genotype in this cohort was 15.0 years, 16.0 for those who were treated with GC.SPP1 rs28357094 acts as a pharmacodynamic biomarker of GC response, and LTBP4 haplotype modifies age at LoA in the CINRG-DNHS cohort. Adjustment for GC treatment and population stratification appears crucial in assessing genetic modifiers in DMD.

SUBMITTER: Bello L 

PROVIDER: S-EPMC4403971 | biostudies-literature | 2015 Apr

REPOSITORIES: biostudies-literature