Background

Rheumatoid Arthritis (RA) is a polygenic disease characterised by localised joint destruction and osteoporosis. The pathogenesis of RA is not completely understood but genetic factors may play a significant role. The genetic polymorphism in the vitamin D receptor (VDR) gene has been described as a significant determinant of bone turnover and mass1. A number of studies have shown contradictory results, but there are no studies on Asiatic Indian RA patients. Alpha-2-macroglobulin (A2M) is involved in modulation of cytokines. TNFRII is involved in tissue destruction2. FcRIIIA has an important role in the clearance of immune complexes and polymorphism from low affinity phenylalanine (F) to high affinity valine (V) binding site has been reported to increase susceptibility/severity of RA in UK Caucasian and North Indo-Pakistani groups3. One of the biological roles for the angiotensin-converting enzyme (ACE) is pro-inflammatory4. ACE is expressed in the synovial membranes from patients with RA suggesting pathophysiological role in the joint angiogenesis with a possibility of localised hypertension. The aim of this study is to assess the role of VDR, TNFRII, A2M and ACE genotypes in the development of RA amongst South Asians. This is a part of our ongoing genetic epidemiological studies on South Asian RA patients.

Methods

The blood samples from 133 South Asians (33 males, 100 females; Age range 29 to 75 years old) with established RA attending Rheumatology referral Clinics in the East Midland hospitals and their siblings (brothers and/or sisters) and random controls from same ethnic groups were collected. Extracted DNA was amplified and analysed for VDR(Bsm1), A2M, TNFRII(196R/M), FcRIIIA(158V/F) and ACE(I/D) loci. The association analysis was performed by computing Odds Ratios and Chi Square values (P 0.05).

ConclusionsOur results suggest that the VDR BB and A2M 22 genotypes were associated with RA among South Asians. The mechanism by which the VDR polymorphism is associated with RA is unknown, but they could be related to immuno-regulatory properties of vitamin D. A2M association may be due to cytokine binding affinity which could modulate the progression of RA. TNFRII and FcRIIIA did not achieve statistical significance. ACE (I/D) polymorphism was also not associated with RA among South Asians. Additional samples are being analysed for these loci and other RA candidate genes to evaluate their role in pathogenesis of RA among Asiatic Indians.

Table 1: VDR, A2M, TNFRII, FcRIIIA and ACE genotypesGroups

BB Bb bb No 1 1 1 2 2 2 No MM RM RR No V V V F F F No II ID DD NoRA 47 60 24 131 83 37 13 133 49 57 23 129 48 28 11 87 48 53 30 131Control 21 108 16 145 105 37 4 146 40 85 17 142 26 31 8 65 50 63 31 144

A2M TNFRII ACEVDR FcRIIIA

Results

Our results (Tables 1-Genotypes & 2-Case vs. Control comparison, Figures 1 to 4-Genotype Frequency) indicate an increased frequency of BB genotypes of VDR gene in Asian RA patients compared to controls leading to highly significant differences (= 24.61, DF 2, P<0.01). Similarly A2M-22 genotype was prominent in RA patients compared to controls (= 6.75, DF 2, P<0.05). TNFRII loci also showed significant chi-square differences (= 6.72, DF 2, P<0.05) but the Odds Ratios were not significant or high. The ACE I/D polymorphism was not associated in the present sample (= 0.305, DF 2, P>0.05). The BB genotype of VDR locus was associated with RA in Asian patients (Odds ratio = 3.30 (95% CI 1.78 – 6.24), = 16.97, P<0.005). Similarly A2M 22 genotype was associated with RA (Odds ratio = 3.85 (95% CI 1.14 – 136.55), = 4.85, P<0.005).

Association Analysis of VDR, Association Analysis of VDR, -2-Macroglobulin, TNFRII, Fc-2-Macroglobulin, TNFRII, FcRIIIA and ACE gene RIIIA and ACE gene polymorphism in South Asian Rheumatoid Arthritis patients of the East Midlands, UK.polymorphism in South Asian Rheumatoid Arthritis patients of the East Midlands, UK.

A. GhelaniA. Ghelani11, A. Pacynko, A. Pacynko11, A. Gilmour, A. Gilmour11, L. Goh, L. Goh22, A. Jones, A. Jones33, A. Samanta, A. Samanta22, J.I. Robinson, J.I. Robinson44, A.W. Morgan, A.W. Morgan44, J.D. Isaacs, J.D. Isaacs55, S.S. , S.S.

MastanaMastana11..

1) Human Sciences, Loughborough University, Loughborough,UK; 2) Leicester Royal Infirmary, Leicester, UK; 3) City Hospital, 1) Human Sciences, Loughborough University, Loughborough,UK; 2) Leicester Royal Infirmary, Leicester, UK; 3) City Hospital,

Nottingham,UK; 4) St. James' University Hospital, Leeds,UK; 5) University Medical School, Newcastle Upon Tyne, UK.Nottingham,UK; 4) St. James' University Hospital, Leeds,UK; 5) University Medical School, Newcastle Upon Tyne, UK.

GroupsBB Bb bb 1 1 1 2 2 2 MM RM RR V V V F F F II ID DD

Odds Ratio

( 95% CI )

3.3 (1.78 - 6.24)

0.29 (0.17 -

0.5)

1.81 (0.87 - 3.83)

0.65 (0.38 - 1.11)

1.14 (0.64 - 2.00)

3.85 (1.14 - 16.55)

1.56 (0.91 - 2.69)

0.53 (0.32 - 0.89)

1.6 (0.74 - 3.36)

1.85 (0.92 - 3.74)

0.52 (0.254 -

1.07)

1.03 (0.35 - 3.16)

1.09 (0.64 - 1.84)

0.87 (0.53 - 1.45)

1.06 (0.58 - 1.96)

16.97 P =

0.000

[3.8 E-5]

22.58 P =

0.000

[2.0 E-6]

2.39

P =

0.122

2.45

P =

0.118

0.11

P =

0.74

4.85

P =

0.028

2.52

P =

0.112

6.04

P =

0.014

1.41

P =

0.236

2.85

P =

0.092

3.14

P =

0.076

0.00

p =

1

.04

P =

0.837

0.19

P =

0.667

0.00

P =

0.947

A2M TNFRII ACEVDR FcRIIIA

Table 2: Odds Ratio and 2 values for each genotype

References1. Morrison et al., Nature 1994; 367: 284-7.2. Barton et al., Arth & Rheum 2001; 44, 61-65.3. Morgan et al. Arth & Rheum 2000; 43,2328-23344. Zapico et al., J Rheumatol 2000; 27, 2308-2311.

E-mail Addresses for contact : A.Ghelani2@lboro.ac.uk A.Ghelani2@lboro.ac.uk S.S.Mastana@lboro.ac.ukS.S.Mastana@lboro.ac.uk

1986/T

0%

20%

40%

60%

80%

Fre

qu

en

cy

BB Bb bb

Figure 1: VDR Genotypes

RA

Control

n = 131 - 145

0%

20%

40%

60%

80%

Fre

qu

en

cy

MM RM RR

Figure 3: TNFRII Genotypes

RA

Control

n = 129 - 142

0%

20%

40%

60%

80%

Fre

qu

en

cy

V V V F F F

Figure 4: Fc RIIIA Genotypes

RA

Control

n = 65 - 87

0%

20%

40%

60%

80%

Fre

qu

en

cy

1 1 1 2 2 2

Figure 2: A2M Genotypes

RA

Control

n = 133 - 146

Frequenc

yFrequenc

y

Frequenc

yFrequenc

y