ACR Meeting Abstracts

ACR Meeting Abstracts

Abstract Number: 1954

Association of Functional (GA)n Microsatellite Polymorphism in the FLI1 Gene with Susceptibility to Human Systemic Sclerosis

Aya Kawasaki1, Keita Yamashita 2, Takashi Matsushita 3, Hiroshi Furukawa 4, Yuya Kondo 5, Naoko Okiyama 6, Shouhei Nagaoka 7, Kota Shimada 8, Shoji Sugii 9, Masao Katayama 10, Shunsei Hirohata 11, Akira Okamoto 12, Noriyuki Chiba 13, Eiichi Suematsu 14, Keigo Setoguchi 15, Kiyoshi Migita 16, Takayuki Sumida 5, Shigeto Tohma 17, Minoru Hasegawa 18, Yasuhito Hamaguchi 3, Shinichi Sato 19, Yasushi Kawaguchi 20, Kazuhiko Takehara 3 and Naoyuki Tsuchiya 1, 1Molecular and Genetic Epidemiology Laboratory, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan, 2Doctoral Program in Biomedical Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Japan, 3Department of Dermatology, Kanazawa University, Kanazawa, Japan, 4Molecular and Genetic Epidemiology Laboratory, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan, 5Division of Rheumatology, Department of Internal Medicine, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan, 6Department of Dermatology, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan, 7Yokohama Minami Kyousai Hospital, Yokohama, Kanagawa, Japan, 8Department of Rheumatic Diseases, Tokyo Metropoitan Tama Medica Center, Fuchu, 9Department of Rheumatic Diseases, Tokyo Metropoitan Tama Medica Center, Fuchu, Japan, 10National Hospital Organization Nagoya Medical Center, Nagoya, Japan, 11Department of Rheumatology and Infectious Diseases, Kitasato University School of Medicine, Tatsuno, Japan, 12National Hospital Organization HImeji Medical Center, Himeji, Hyogo, Japan, 13National Hospital Organization Morioka Medical Center, Morioka, Iwate, Japan, 14National Hospital Organization Kyushu Medical Center, Fukuoka, Japan, 15Tokyo Metropolitan Cancer and Infectious Dease Center Komagome Hospital, Tokyo, Tokyo, Japan, 16Department of Rheumatology, Fukushima Medical University School of Medicine, Fukushima, Japan, 17National Hospital Organization Tokyo National Hospital, Kiyose, Japan, 18Department of Dermatology, Fukui University, Fukui, 19University of Tokyo Graduate School of Medicine, Department of Dermatology, Tokyo, Japan, 20Department of Rheumatology, Tokyo Women’s Medical University, Tokyo, Japan

Meeting: 2019 ACR/ARP Annual Meeting

Keywords: , ,

Session Information

Date: Tuesday, November 12, 2019

Title: Genetics, Genomics & Proteomics Poster

Session Type: Poster Session (Tuesday)

Session Time: 9:00AM-11:00AM

Background/Purpose: Susceptibility genes which can account for the characteristic features of systemic sclerosis (SSc) such as fibrosis, vasculopathy and autoimmunity remain to be determined. A series of extensive studies by Asano and colleagues using genetically engineered mice convincingly demonstrated that deficiency of a transcription factor Fli1 can play a causal role in the development of SSc with all these characteristic features. Although previous genome-wide association studies (GWAS) have not reported association of single nucleotide polymorphisms (SNVs) in the FLI1 gene, FLI1 contains (GA)n microsatellite in its regulatory region, which has been shown to be associated with expression level of FLI1. Because microsatellite polymorphisms are not usually captured by GWAS unless they are in tight linkage disequilibrium with SNVs, we thought it is possible that FLI1 microsatellite may partly account for the “missing heritability” of SSc. In this study, we directly genotyped FLI1 (GA)n microsatellite and examined whether it is associated with susceptibility to SSc.

Methods: Genomic DNA from 639 Japanese SSc patients and 851 healthy controls (HCs) was genotyped for (GA)n microsatellite using the fragment assay. In the discovery stage, the genotype distribution was compared between 479 patients and 573 HCs, and the cut-off repeat number for the susceptibility to SSc was determined by receiver operating characteristic (ROC) analysis to classify the alleles into L (long) and S (short) alleles. In the replication stage, 160 patients and 268 HCs were examined, and the data from both stages were combined using meta-analysis. Association with susceptibility and clinical characteristics was examined using logistic regression analysis with the adjustment for sex. FLI1 mRNA levels were determined using quantitative RT-PCR.

Results: In the discovery stage, genotype distribution of the (GA)n microsatellite alleles in SSc patients showed a trend towards extension as compared with that in the HCs (Cochran-Armitage test for trend, P=0.045)(Figure 1). Based on the ROC analysis, (GA)n alleles with ≥22 repeats were collectively defined as L alleles, and alleles with ≤21 repeats as S alleles. The same trend was observed in the discovery and replication stages, and when combined, (GA)n L alleles were significantly associated with susceptibility to SSc (P=5.0E-04, odds ratio[OR]=1.34, 95% confidence interval 1,14-1.58, additive model)(Table 1). Significant association was observed both in diffuse cutaneous and limited cutaneous SSc. Among the SSc, (GA)n L alleles were significantly enriched in the patients with modified Rodnan total skin thickness score (mRSS)≥10 compared with those with mRSS< 10 (P=9.6E-03, OR=1.63). FLI1 mRNA level in the whole blood was significantly reduced in SSc patients when compared with HCs(Figure 2a). When the mRNA levels were compared between the carriers and non-carriers of (GA)n L alleles among HCs, significant reduction was observed in individuals carrying (GA)n L allele (Figure 2b).

Conclusion: FLI1 (GA)n microsatellite alleles with extended repeat numbers were associated with lower FLI1 mRNA levels and susceptibility to human SSc.

Figure　1. Distribution of FLI1 -GA-n microsatellite alleles in the patients with systemic sclerosis and healthy controls in the discovery stage.
X and Y axes show the repeat number and allele frequency -%- of FLI1 -GA-n microsatellite, respectively. The distribution in SSc patients was significantly shifted to extended alleles when compared with healthy controls -Cochran-Armitage test for trend, P=0.045-. The dotted line shows the cutoff value for the susceptibility to SSc derived from the receiver operating characteristic -ROC- analysis

Figure 2. FLI1 mRNA expression in whole peripheral blood.
The band and quartiles in the boxplot diagrams indicate median -Q2- and interquartile range -IQR- of FLI1 mRNA expression levels. P values were calculated by Mann-Whitney U-test. -a- Patients with SSc and HCs -all genotypes combined-. HCs: n=19, Q2=1.07, IQR=0.23. SSc: n=8, Q2=0.76, IQR=0.24. -b- Healthy controls carrying -L alleles 1 or 2- and not carrying -L allele 0- -GA-n L alleles. -L allele 0: n=9, Q2=1.20, IQR=0.18, L allele 1or 2: n=10, Q2=0.97, IQR=0.14.-

Disclosure: A. Kawasaki, None; K. Yamashita, None; T. Matsushita, None; H. Furukawa, Ajinomoto Co., Inc., 8, Ayumi Pharmaceutical Corporation, 8, Bristol-Myers Squibb Co., 2, Daiichi Sankyo Co., Ltd., 8, Dainippon Sumitomo Pharma Co., Ltd., 8, Daiwa Securities Health Foundation, 2, Japan Research Foundation for Clinical Pharmacology, 2, Kato Memorial Trust for Nambyo Research, 2, Luminex Japan Corporation Ltd., 8, Mitsui Sumitomo Insurance Welfare Foundation, 2, Nakatomi Foundation, 2, Pfizer Japan Inc., 8, Takeda Pharmaceutical Company, 8, Takeda Science Foundation, 2, The Nakatomi Foundation, 2; Y. Kondo, None; N. Okiyama, None; S. Nagaoka, None; K. Shimada, None; S. Sugii, None; M. Katayama, None; S. Hirohata, None; A. Okamoto, None; N. Chiba, None; E. Suematsu, None; K. Setoguchi, None; K. Migita, None; T. Sumida, None; S. Tohma, Abbott Japan Co, Ltd., 2, Abbott Japan Co., Ltd., 2, AbbVie GK., 8, Asahi Kasei Pharma Corporation, 8, Astellas Pharma Inc, 2, Astellas Pharma Inc., 2, 8, Chugai Pharmaceutical Co, Ltd., 2, Chugai Pharmaceutical Co., Ltd., 2, 8, Eisai Co, Ltd., 2, Eisai Co., Ltd., 2, Merck Sharp and Dohme Inc., 2, Mitsubishi Tanabe Pharma Corporation, 2, 8, Ono Pharmaceutical Co., Ltd., 8, Pfizer Japan Inc, 2, Pfizer Japan Inc., 2, 8, Takeda Pharmaceutical Company Limited, 2, Teijin Pharma Limited, 2; M. Hasegawa, None; Y. Hamaguchi, None; S. Sato, None; Y. Kawaguchi, None; K. Takehara, None; N. Tsuchiya, Ayumi Pharmaceutical Corporation, 8, Bristol-Myers Squibb, 2, Bristol-Myers Squibb Co. Ltd, 2, Japan College of Rheumatology, 2, Japan Rheumatism Foundation, 2.

To cite this abstract in AMA style:

Kawasaki A, Yamashita K, Matsushita T, Furukawa H, Kondo Y, Okiyama N, Nagaoka S, Shimada K, Sugii S, Katayama M, Hirohata S, Okamoto A, Chiba N, Suematsu E, Setoguchi K, Migita K, Sumida T, Tohma S, Hasegawa M, Hamaguchi Y, Sato S, Kawaguchi Y, Takehara K, Tsuchiya N. Association of Functional (GA)n Microsatellite Polymorphism in the FLI1 Gene with Susceptibility to Human Systemic Sclerosis [abstract]. Arthritis Rheumatol. 2019; 71 (suppl 10). https://acrabstracts.org/abstract/association-of-functional-gan-microsatellite-polymorphism-in-the-fli1-gene-with-susceptibility-to-human-systemic-sclerosis/. Accessed .

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