Received: 26 August 2018 | Accepted: 31 October 2018 DOI: 10.1002/jcb.28120 RESEARCH ARTICLE Association study of copy number variation in BMP8A gene with the risk of ankylosing spondylitis in Iranian population Sara Shahba 1,2 | Reza Jafari Shakib 3 | Ahmadreza Jamshidi 2 | Mahdi Vojdanian 2 | Maryam Akhtari 2 | Saeed Aslani 2 | Shiva Poursani 2 | Iraj Nikokar 4 | Mahdi Mahmoudi 2 1 Medical Biotechnology Research Center, School of Paramedicine, Guilan University of Medical Sciences, Rasht, Iran 2 Rheumatology Research Center, Tehran University of Medical Sciences, Tehran, Iran 3 Department of Immunology, School of Medicine, Guilan University of Medical Sciences, Rasht, Iran 4 Laboratory of Microbiology and Immunology of Infectious Diseases, School of Paramedicine, Guilan University of Medical Sciences, Rasht, Iran Correspondence Jafari‐Shakib Reza, Department of Microbiology and Immunology, Faculty of Medicine, Guilan University of Medical Sciences, Rasht P.O. Box 41635‐3363, Iran. Email: shakib@gums.ac.ir Mahdi Mahmoudi, Rheumatology Research Center, Shariati Hospital, Kargar Ave., Tehran P.O. Box 1411713137, Iran. Email: mahmoudim@tums.ac.ir Funding information Tehran University of Medical Sciences and Health Services, Grant/Award Number: 94‐04‐41‐31178; Guilan University of Medical Sciences, Grant/ Award Number: 95012102 Abstract Background: Copy number variation (CNV) of DNA segments has been considered as an important component of genetic variation, affecting the quality and quantity of gene expression. Bone morphogenic protein 8A (BMP8A) has been reported to function in bone formation. With respect to the bone and joint complications in ankylosing spondylitis (AS), this investigation aimed to study the role of BMP8A gene CNV in impressing the gene expression as well as the disease risk. Methods: A total of 900 individuals, including 450 patients with AS and 450 healthy controls were enrolled. The copy numbers of BMP8A gene were detected by TaqMan real‐time polymerase chain reaction (PCR) method. BMP8A messenger RNA (mRNA) transcript level in peripheral blood mono- nuclear cells (PBMCs) was also measured by SYBR Green real‐time gene expression PCR method. Results: No significant association of BMP8A copy number was detected with the risk of AS. BMP8A mRNA expression level was significantly downregulated in patients compared with controls. mRNA expression level of BMP8A in both AS patients with and without syndesmophyte was significantly lower than the healthy control group. There was no correlation between the mRNA expression level of BMP8A and both demographic and clinical data of the patients. Conclusions: Although BMP8A gene expression was downregulated in patients with AS, its copy number could not affect the transcript level of BMP8A gene in PBMCs and was not associated with susceptibility to AS in Iranian population. BMP8a may take into account as an indicator of bone formation process in AS, but it seems that mechanisms other than CNV may regulate this protein. KEYWORDS ankylosing spondylitis (AS), bone morphogenic protein 8A, copy number variations (CNVs) J Cell Biochem. 2018;1-7. wileyonlinelibrary.com/journal/jcb © 2018 Wiley Periodicals, Inc. | 1