Apolipoprotein E 4 allele is associated with low bone density in postmenopausal women

Apolipoprotein E (Apo E) genotypes have been associated with a number of involutional disorders. Recently some studies have examined whether the Apo E 4 allele might play a role in the pathophysiology of postmenopausal osteoporosis. However, association analysis between Apo E genotypes, BMD, bone loss or fracture risk have not brought universal findings. The aim of this study was, therefore, to determine the relationship between the presence or absence of Apo E 4 allele and BMD in postmenopausal women of Caucasian origin. We studied 113 women, age 62.5 +/- 8.9 yr, who underwent measurement of hip and spine BMD by dual-energy absorptiometry (DXA, g/cm2). Apo E genotypes were assessed by PCR amplification and by restriction typing with Cfol enzyme. The Apo E allele frequencies in the study population were as follows: E2 0.084, E3 0.845, E4 0.071. Because the Apo E 4 allele was associated with osteoporosis in previous studies, the probands were dichotomized by the presence or absence of Apo E 4 allele. After adjustment for BMI and years since menopause BMD at the lumbar spine varied significantly by Apo E 4 status. Women with Apo E 4 allele had significantly lower BMD at the lumbar spine than women with no Apo E 4 allele (p<0.003, ANCOVA). In contrast, there were no significant differences in BMD at the hip comparing women with or without the Apo E 4 allele. To conclude, these data may support the importance of Apo E 4 allele in determining postmenopausal spine bone mass.