Objectives. We have previously investigated an association between the genome copy number variation (CNV) and acetabular dysplasia (AD). Hip osteoarthritis is associated with a genetic polymorphism in the aspartic acid repeat in the N-terminal region of the asporin (ASPN) gene; therefore, the present study aimed to investigate whether the CNV of ASPN is involved in the pathogenesis of AD. Methods. Acetabular coverage of all subjects was evaluated using radiological findings (Sharp angle, centre-edge (CE) angle, acetabular roof obliquity (ARO) angle, and minimum joint space width). Genomic DNA was extracted from peripheral blood leukocytes. Agilent’s region-targeted high-density oligonucleotide tiling microarray was used to analyse 64 female AD patients and 32 female control subjects. All statistical analyses were performed using EZR software (Fisher’s exact probability test, Pearson’s correlation test, and Student’s t-test). Results. CNV analysis of the ASPN gene revealed a copy number loss in significantly more AD patients (9/64) than control subjects (0/32; p = 0.0212). This loss occurred within a 60 kb region on 9q22.31, which harbours the gene for ASPN. The mean radiological parameters of these AD patients were significantly worse than those of the other subjects (Sharp angle, p = 0.0056; CE angle, p = 0.0076; ARO angle, p = 0.0065), and all nine patients required operative therapy such as total hip arthroplasty or pelvic osteotomy. Moreover, six of these nine patients had a history of operative or conservative therapy for developmental dysplasia of the hip. Conclusions. Copy number loss within the region harbouring the ASPN gene on 9q22.31 is associated with severe AD. A copy number loss in the ASPN gene region may play a role in the aetiology of severe AD. Cite this article: T. Sekimoto, M. Ishii, M. Emi, S. Kurogi, T. Funamoto, Y. Yonezawa, T. Tajima, T. Sakamoto, H. Hamada, E. Chosa. Copy number loss in the region of the ASPN gene in patients with acetabular dysplasia: ASPN CNV in acetabular dysplasia. Bone Joint Res 2017;6:439–445. DOI: 10.1302/2046-3758.67.BJR-2016-0094.R1

Introduction. Several disorders have been associated with genetic variants. Copy number variations (CNVs) are documented micro DNA insertions and deletions that may be ten times more frequent than point mutations. We undertook a genome-wide scan to find CNVs associated with adolescent idiopathic scoliosis (AIS). Methods. 879 white individuals with AIS severe spine curvatures and 1486 white controls were evaluated for CNVs with the Affymetrix 6.0 HUSNP array. After implementation of quality filters, data were quantile normalised. Copy number analysis was done with Helix Tree (Golden Helix, Bozeman, MT, USA). The copy number segments were measured with the Golden Helix's univariate segmentation algorithm. Statistically different segments were extracted with mean Log2 ratio intensity for that segment to highlight deletions, neutrals, and duplications. We then undertook association analysis on those segments. A p value of less than 10–7 was regarded as significant. Results. We recorded 143 significant segments or regions associated with AIS. 94 of these regions showed gains of copy whereas 49 had deletions. 63 of these significant regions map to known genes. Biological functions of the proteins coded by the genes identified complex groups associated with embryonic development, nervous system development and function, and bone and soft tissue development. These groups present an extensive overlap with the biological function groups that were generated with associated single-nucleotide polymorphism data from the same group of individuals. Conclusions. For the first time we show significant copy number loss or gain in several genomic regions for patients with AIS with severe spine curves compared with a control population. We are testing CNVs in patients with a mild spine curvature to establish whether they improve the performance of AIS prognostic testing. The identification of novel or rare CNVs in severe cases of AIS could lead to the enhancement of prognostic testing and help to identify specific biological pathways that cause AIS or accelerate AIS progression

Ollier disease is a rare skeletal disorder. It is characterized by the occurrence of multiple enchondromas with a marked unilateral predominance mainly affecting medulla of the metaphyses and diaphyses of the short and long tubular bones of the limbs, especially the hands and feet. The risk of malignant transformation is suggested to be up to 35%. We hypothesise that Ollier disease is a mosaic condition as it is polyostotic and because of its unilateral predominance. Here we aimed to identify molecular defects in Ollier disease related enchondromas and chondrosarcomas using high resolution single nucleotide polymorphism (SNP) array approach. Affymetrix SNP 6.0 was performed on 67 samples which include 10 blood samples and 3 matched blood-saliva samples as a control; 13 enchondromas and 26 chondrosarcomas of different grades from 30 Ollier patients and normal DNA from 12 Ollier patients for paired comparison. All samples were divided into three groups: normals, enchondromas and chondrosarcomas. The number of numerical genomic changes in the chromosomes were not different for the enchondromas (p=0.36) while large genomic aberrations were seen in chondrosarcomas as compared to normals (p=0.01). Copy number variation (CNV) analysis showed 95K amplification at 4q13 in 5 out of 13 enchondromas and a 2K deletion at 14q11 in 6 out of 13 enchondromas. Paired loss of heterozygosity (LOH) analysis failed to show LOH in 5 enchondromas at higher resolution. Paired LOH was observed at 3q, 5p, 6p, 6q, 7q, 9p, 12p, 13p and 13q in 7 high grade chondrosarcomas associated with loss of chromosomes. The results of this study indicate involvement of chromosomes 4 and 14 for the development of enchondromas. We were unable to detect LOH in enchondromas at 1Mb resolution containing approximately 500 SNP probes. High grade chondrosarcomas showed LOH at different chromosomes. In future, we will study LOH and CNV changes at gene level and select candidate genes