Relationship between the Apolipoprotein AI, B gene polymorphism and the risk of non-traumatic osteonecrosis

Ji-Min Yin 0 2 Zhao Liu 1 Shi-Chang Zhao 0 2 Yan-Jie Guo 0 2 Zhong-Tang Liu 0 2 0 Department of Orthopedic Surgery, Shanghai Sixth People's Hospital, Shanghai Jiaotong University , No.600 Yishan Road, Shanghai 200233 , China 1 Department of hematology, Shanghai Rui Jin Hospital, Shanghai Jiao Tong University School of Medicine , Shanghai , China 2 Department of Orthopedic Surgery, Shanghai Sixth People's Hospital, Shanghai Jiaotong University , No.600 Yishan Road, Shanghai 200233 , China Background: Previous studies suggested that Apolipoprotein AI (ApoAI) and apolipoprotein B (ApoB) gene polymorphisms may result in lipid metabolism disorders. Genetic polymorphisms in these genes may be associated with the occurrence of osteonecrosis. Methods: We designed a case-control study including 429 patients of osteonecrosis and 368 age- and sex-matched control subjects. Polymerase chain reaction was used to amplify the DNA fragments in promoter -75 G > A of ApoAI gene and EcoR I, Xba I and 3-VNTR of ApoB gene in osteonecrosis patients and healthy controls. We utilized polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method to genotype these four single nucleotide polymorphisms (SNPs). Results: For -75 G > A polymorphism of ApoAI, AA genotype frequency (0.501) was significantly higher in patients with osteonecrosis than that in control (0.462) subjects (P <0.001), GA genotype frequency (0.170) was significantly lower than that in the control (0.310) group (P <0.0001). In osteonecrosis patients, the odds ratio (OR) of A allele was 3.932 (95% CI: 3.0847 ~ 5.0123), which suggested that subjects carrying A allele of promoter region -75 G > A of ApoAI gene had higher susceptibility to osteonecrosis than G allele carriers. The genotype and allele frequency distributions showed no significant difference in EcoR I, Xba Iand 3-VNTR loci of ApoB gene between the osteonecrosis group and control group. Conclusion: Our study suggested that ApoAI gene -75G > A polymorphism may be associated with susceptibility to osteonecrosis in Chinese population. However, our results need further investigation with large sample size and various populations. - Introduction Osteonecrosis is one kind of orthopedic refractory disease and is divided into traumatic and non-traumatic one. Non-traumatic osteonecrosis, with rapid progression, is common seen in young people [1]. Currently, the whole population of osteonecrosis is about 7 million people in China, and new cases have reached 100-200 thousand each year [2]. Previous studies indicated that the abnormal lipid metabolism is known to be the main pathogenesis of osteonecrosis [3]. Heavy drinking and excessive use of corticosteroids may result in abnormal lipid metabolism in general populations [4]. Therefore, among the etiologies of osteonecrosis, both of them were commonly considered to have the same pathogenesis. Studies showed that the incidence of coronary heart disease (CHD) was associated with abnormal ApoAI and ApoB levels resulting from apoAI and apoB gene polymorphisms [5-7]. However, the relationship between these polymorphisms and non-traumatic osteonecrosis has not been systematically studied. In 2007, Hirata et al. [8] performed a case-control study to reveal the relation between ApoAI and ApoB genetic polymorphisms and osteonecrosis in a Japanese population. In their study, four SNPs including C7623T and G12619A for the ApoB gene and G75A and C83T for the ApoAI gene were analyzed using PCR-RFLP and TaqMan realtime PCR method. The authors found C7623T polymorphism of ApoB gene was associated with osteonecrosis. Subsequently, Wang et al. [9] found -75 G > A polymorphism was associated with osteonecrosis in Chinese population. However, the sample sizes of these two studies were very small. Up to date, a number of SNPs of ApoAI and ApoB were reported, such as -75 G > A, +75 bp and +83 bp loci of Apo AI gene, Eco RI loci, Xba I loci and 3-VNTR of Apo B gene, which were reported to be associated with several disease [8-13]. To further clarify the association of ApoAI and ApoB genetic polymorphism and osteonecrosis, we designed a larger sample-size case-control study. Subjects and methods Ethics The present study has been performed with the approval of the ethics committee of Shanghai Jiaotong University and was in compliance with the Helsinki Declaration. The informed consents of the study were collected from all the candidate subjects. Subjects All the patients were selected from November 2001 to September 2013 in Shanghai Sixth Peoples Hospital. All the patients were consistent with the diagnostic criteria of osteonecrosis proposed in 1995 by Mont et al. [14]. They were all confirmed by clinical diagnosis, double hip X-ray image, CT scan or MRI examination. A total of 429 cases including 326 male and 103 female with the average age of 44.6 11.3 years were included. Exclusion criteria: 1) Primary disease in serious condition which required hormone (...truncated)