The COL1A1 SP1 polymorphism is associated with lower bone mineral density in patients treated with valproic acid.

OBJECTIVE

The aim of this study was to determine the possible relationship between the Sp1 polymorphism of gene COL1A1 and bone metabolism disorder in individuals with epilepsy.

METHODS

To this end, we carried out an observational cross-sectional study on 64 patients in monotherapy with an antiepileptic drug. The patients were classified on the basis of the presence of the 's' allele of the COL1A1 Sp1 polymorphism.

RESULTS

In the patients with SS, the standardized bone mineral density (sBMD) in the left femoral neck was 1024.9±206.1 mg/cm, whereas in the patients with Ss or ss, the density was significantly lower, 917±141.4 mg/cm (P=0.027), as was the femoral t-score (0.72±1.67 vs. -0.29±1.15, P=0.01). The values in the lumbar spine were equally greater in those with SS: 1219.1±236.3 versus 1090.5±142.7 mg/cm for the sBMD (P=0.018) and 0.67±1.98 versus -0.34±1.16 for the lumbar t-score (P=0.023). The bone biomarkers showed no significant differences nor did the 25-OH vitamin D and parathormone values. In the patient group treated with valproic acid (VPA), the densitometric values were significantly lower in the Ss or ss patients compared with SS homozygotes: 887.1±142.6 versus 1120.6±198.2 mg/cm for femoral sBMD (P=0.02), 990±98.1 versus 1417±251.2 mg/cm for lumbar sBMD (P=0.001). Of the patients who were carriers of the 's' allele and who were treated with VPA, 86% achieved osteopenia values.

CONCLUSION

In our study, the presence of the 's' allele of the COL1A1 Sp1 polymorphism in individuals with epilepsy was related to lower bone BMD (lumbar and femoral). This relationship seemed to be further apparent in the patients undergoing treatment with VPA.