Table 3

Tests of association between ENPP1 polymorphisms and osteoarthritis (OA) of hand joints

Marker
Allele/haplotype
Freq.
P values of TDT
Combined P values for 3 testsa
Bonferroni correction
n inf.
n test
Pedigree-based disequilibrium test







FBAT
QTDTb
EOT
A
B
A
B


P
Δ (years)

M06NR1A
4Fc
0.27
0.0001
1.0e-5
0.0009
<1.0e-6
<5.0e-5
<4.0e-6
<2.0e-5
84
4
0.0002
-3.5
K173Q
1
0.11
0.0129
0.0347
0.0403
0.0020
0.0104
0.0020
0.0104
48
1
0.0196
1.9
_XXXd
_221
0.66
0.0147
0.0174
0.0043
0.0002
0.0033
0.0006
0.0099
88
3
0.3430
-1.3
_XXX
_211
0.10
0.0148
0.0373
0.0096
0.0007
0.0074
0.0021
0.0220
39
3
0.0110
2.3
_XX_
_22_
0.67
0.0046
0.0050
0.0030
1.8e-5
0.0006
0.0001
0.0018
89
3
0.1827
-1.7
_XX_
_21_
0.10
0.0114
0.0378
0.0091
0.0005
0.0062
0.0016
0.0185
40
3
0.0114
2.3
__XX
__11
0.12
0.0426
0.0509
0.0426
0.0074
0.0177
0.0147
0.0351
47
2
0.0278
2.1
__XX
__21
0.85
0.0362
0.0515
0.0576
0.0082
0.0205
0.0164
0.0406
58
2
0.1574
-1.6

Osteoarthritis scores were measured by the Kellgren–Lawrence method [19]. K–L scores of 28 joints on both hands, which were used as primary phenotype. The primary phenotype was subjected to principal component analysis resulting in first factor scores (FS1-OAs). After being adjusted for age, FS1-OA was used as a quantitative trait for the association tests. aCombined P value using χ2 (A) and simulated three-dimensional null distribution (B). bColumn presents orthogonal test, which uses parent trait values as covariates. cF is an artificial 'allele' combining all rare alleles but not the three most frequent ones. dXXXX is the haplotype of the four SNPs (rs1800949, rs858342, K173Q, and R774C). The minor allele frequencies of the four individual SNPs in the study population are 0.24 for the T-allele (2) of rs1800949, 0.21 for the G-allele (1) of rs858342, 0.11 for the C-allele (1) of K173Q, and 0.03 for the T-allele (2) of R774C. Δ, mean difference between the allele carriers and other individuals in age at onset of the disorder; EOT = extreme offspring design t-test; FBAT, family-based association test; Freq., frequency; n inf., number of informative families for TDT in the sample; n test, number of tests performed for the marker (alleles with n inf. >40); QTDT, quantitative transmission disequilibrium test; TDT, transmission disequilibrium test.

Suk et al. Arthritis Research & Therapy 2005 7:R1082   doi:10.1186/ar1786

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