ASSOCIATION OF BONE TURNOVER MARKERS WITH APOE4 ALLELE IN SUBJECTS WITH OSTEOPOROTIC FRACTURES.

The available reports on the association of APOE4 allele with osteoporosis are not consistent. Also, there are limited studies on the association of APOE genotypes with bone turnover markers. Therefore, the present study aims to test the hypothesis; whether there is an association of APOE4 allele with osteoporosis and bone turnover markers. The current study involved 130 individuals of ≥50 years of age with osteoporotic fractures as cases and; age and gender-matched individuals without osteoporotic fractures as controls. The BMD was tested by ultrasound bone (heel) densitometry. The serum calcium, phosphorus & ALP were measured using automated chemistry analyzer. Serum β-crosslaps and osteocalcin were measured using automated immunoassay analyzer. APOE genotypes were determined by sequencing blood DNA using Sanger method. The results showed significantly reduced BMD in cases when compared to the controls (T-score of -3.05 vs. -1.57). Though, all the biochemical parameters except β-crosslaps were in clinically normal range, a statistically significant decrease in calcium and an increase in osteocalcin and β-crosslaps in cases were observed at p<0.05. There was no significant difference in frequency of APOE alleles (E2, E3 and E4) between cases and controls. Also, there was no association of osteoporosis (BMD) with APOE4 allele whereas, β-crosslaps and osteocalcin showed a significant increase in subjects with APOE4 allele among cases but not in controls. In conclusion, though there is no association of APOE4 allele with osteoporosis, the present study found a significant association of APOE4 allele with bone turnover markers (osteocalcin and β-crosslaps) in osteoporotic subjects.