ABCMdb

PMID: 20368174

Matsuo H, Takada T, Ichida K, Nakamura T, Nakayama A, Ikebuchi Y, Ito K, Kusanagi Y, Chiba T, Tadokoro S, Takada Y, Oikawa Y, Inoue H, Suzuki K, Okada R, Nishiyama J, Domoto H, Watanabe S, Fujita M, Morimoto Y, Naito M, Nishio K, Hishida A, Wakai K, Asai Y, Niwa K, Kamakura K, Nonoyama S, Sakurai Y, Hosoya T, Kanai Y, Suzuki H, Hamajima N, Shinomiya N
Common defects of ABCG2, a high-capacity urate exporter, cause gout: a function-based genetic analysis in a Japanese population.
Sci Transl Med. 2009 Nov 4;1(5):5ra11., [PubMed]

Sentences

No. Mutations Sentence Comment

1 ABCG2 p.Gln126* Because this gene is responsible for giving rise to a protein namely the Q126X nonfunctional mutation, confers an even higher risk associated with an increase in uric acid ,ABCG2Now, a team led by Hirotaka Matsuo report that in a Japanese population, another risk variant in high-risk variant in nearly 10% of gout cases in Caucasians. Login to comment 3 ABCG2 p.Gln141Lys This study identified Q141K as aABCG2gout in individuals carrying variants in a multifunctional transporter gene, based study supported an association between urate levels and-remained largely unclear. Login to comment 12 ABCG2 p.Gln126* Sequencing of the ABCG2 gene in 90 hyperuricemia patients revealed several nonfunctional ABCG2 mutations, including Q126X. Login to comment 13 ABCG2 p.Gln141Lys Quantitative trait locus analysis of 739 individuals showed that a common dysfunctional variant of ABCG2, Q141K, increases serum uric acid. Login to comment 14 ABCG2 p.Gln141Lys ABCG2 p.Gln126* Q126X is assigned to the different disease haplotype from Q141K and increases gout risk, conferring an odds ratio of 5.97. Login to comment 46 ABCG2 p.Gln141Lys ABCG2 p.Val12Met ABCG2 p.Ser441Asn ABCG2 p.Gln126* ABCG2 p.Gly268Arg The following six nonsynonymous mutations were found: V12M, Q126X, Q141K, G268R, S441N, and F506SfsX4 (Table 1). Login to comment 48 ABCG2 p.Gln141Lys ABCG2 p.Val12Met ABCG2 p.Gln126* Maekawa et al. reported that allele frequencies for these SNPs, which are quite common in the Japanese population, were 31.9% for Q141K, 19.2% for V12M, and 2.8% for Q126X, respectively (Table 1) (34). Login to comment 49 ABCG2 p.Gln141Lys ABCG2 p.Val12Met ABCG2 p.Gln126* Using Hardy-Weinberg equilibrium and these data of a Japanese population reported by Maekawa et al. (34), we calculated estimates of the frequencies of Japanese individuals with these minor alleles to be 53.6% for Q141K, 34.7% for V12M, and 5.5% for Q126X. Login to comment 52 ABCG2 p.Gln141Lys ABCG2 p.Ser441Asn ABCG2 p.Gln126* ABCG2 p.Gly268Arg ATP-dependent transport of urate was reduced by approximately half (46.7%) in Q141K and was nearly eliminated in Q126X, G268R, S441N, and F506SfsX4 mutants (Fig. 2B). Login to comment 53 ABCG2 p.Gln141Lys ABCG2 p.Gln126* Western blot analysis showed that ABCG2 protein expression levels in the Q141K variant decreased by half (47.2%), whereas Q126X resulted in no protein on membrane vesicles (fig. S4). Login to comment 54 ABCG2 p.Gln141Lys The decreased activity of Q141K is probably a result of decreased amounts of ABCG2 protein, consistent with our previous study on ES transport (29). Login to comment 55 ABCG2 p.Val12Met The V12M variant did not show any changes in urate transport or in protein amounts relative to wild-type ABCG2. Login to comment 57 ABCG2 p.Gln141Lys Common variant of ABCG2 increases SUA concentrations Quantitative trait locus (QTL) analysis of SUA was performed with the high-frequency dysfunctional variant Q141K in ABCG2 in a random sample of 739 Japanese individuals. Login to comment 67 ABCG2 p.Gln141Lys All results are expressed as means ± SD. SUA significantly increased as the number of minor alleles of Q141K increased (P = 6.60 × 10-5 ), and when adjusted for sex, the corrected P value is 2.02 × 10-6 (Fig. 2C). Login to comment 69 ABCG2 p.Gln141Lys Different from SUA, Q141K had no significant association with other clinical parameters such as age, body mass index, or sex (table S2). Login to comment 71 ABCG2 p.Gln126* Additional genotyping and association analysis of gout Through additional genotyping of ABCG2 SNPs for 228 Japanese men with hyperuricemia (including 161 men with gout), Q126X homozygous (n = 2) and heterozygous (n = 24) mutations were identified (Table 2). Login to comment 72 ABCG2 p.Gln126* Two patients with Q126X homozygous mutations showed very high SUA (>10 mg/dl)before they were treated for hyperuricemia. Login to comment 74 ABCG2 p.Gln126* The association study showed that Q126X increased the risk of hyperuricemia [odds ratio (OR), 3.61; 95% confidence interval (CI), 2.14-6.08; P = 2.91 × 10-7 ]. Login to comment 75 ABCG2 p.Gln126* ABCG2 p.Gln126* Among the 161 patients with gout, Q126X homozygous (n = 1) and heterozygous (n = 21) mutations were found, which revealed that Q126X dramatically increased gout risk (OR, 4.25; 95% CI, 2.44-7.38; P = 3.04 × 10-8 ). Login to comment 76 ABCG2 p.Gln141Lys The partially functional SNP Q141K also increased gout risk (OR, 2.23; 95% CI, 1.75-2.87; P = 5.54 × 10-11 ). Login to comment 77 ABCG2 p.Gln141Lys ABCG2 p.Val12Met ABCG2 p.Val12Met ABCG2 p.Ser441Asn ABCG2 p.Gln126* ABCG2 p.Gln126* ABCG2 p.Gly268Arg The call rate, or the ability of the SNP to be reliably decoded, for V12M, Q126X, and LS N N SV FLC S P T AN FK G LM ETS S E V F I P Q G N T N G FV P A A AS LD V S N I C Y R V K K RKPVEKEILSNINGIKPGLNAILGPG GGKSSL LDVLA ARKDP S G T L S G D V L I G A P PR A N F K N S G Y Q D D V V M G T L T V R NE LV VC H Q F S A A A RL L T T TNEKNER HINRVIQELGLDKVADSKVGTQFIRGVG GERR KTSIGME L I T D P S I L F L D E P T T G L D S S T A N A V LL L L K R M S K Q G R I I F S T S I H Q P R Y M S I F K LFDSLTLLASGRLMFHGPAQEALGYFESAGYHCEAN YN T V A L N R E E D F K A T E II E P S K Q D K L I E L A EK I Y V N S S F Y K ETKAELHQLSGGEKKKKITVFKEISYTTSFCHQRWVK SRS AFFLDII N G D S A PD P L F K N LL G N P Q A S A I V G I I T L V A FI I Q V V L G Y AVEFLKNDST G I Q N R A G V L F F L T T Q C F S L V S S N G L S L M L I T P M S F I FV D L R P I C Y W L W Y I Y T Q S R F L NQ S L F P G A H E F Y S Y S E F R G Y I K V K S V Y I H L E V A S S V L M A A M F V A F M S Y M T M F K A T I M L H F I A V K G W I L V C A N L W V A T L M T C F VI F M M I F S G L L VNLTTIASAIAAGQS L S V V LKGL L F N Q L F P S L D Y G Q K V L C Y EEGTCTAYNCPNNGTAN G P G L K L L L K K SYF L Y D L G L M A P K Extracellular Intracellular 50 150 200 300 100 350 395 415 469 450 470 500 525 550 565 585 600 625 608 650 250 655 603 475 644 F506SfsX4 (F506fs) V12M Q126X Q141K S441N G268R V Q F S G Q # C signature Walker B motif Walker A motif C D E 4.0 4.5 5.0 5.5 6.0 C/C C/A A/A Male + female P= 2.02 x 10 -6 5.0 5.5 6.0 6.5 7.0 C/C C/A A/A Male P= 0.0144 Serumuric acid(mg/dl) 4.0 4.5 5.0 5.5 6.0 C/C C/A A/A Female P= 0.0137 (pmol/mgprotein) 0 20 40 60 80 100 120 140 160 180 200 + AMP + ATP B Serumuric acid(mg/dl) Serumuric acid(mg/dl) A [C]Uratetransport 14 G F M C-terminal N-terminal Fig. 2. Login to comment 84 ABCG2 p.Gln141Lys Results are expressed as means ± SD. (C to E) QTL analysis of Q141K and SUA concentrations was performed in 739 Japanese individuals (C), including 245 male subjects (D) and 494 female subjects (E). Login to comment 85 ABCG2 p.Gln141Lys "C/C," "C/A," and "A/A" indicate wild-type subjects, heterozygous mutation carriers, and homozygous mutation carriers of Q141K, respectively. Login to comment 89 ABCG2 p.Gln141Lys ABCG2 p.Val12Met ABCG2 p.Ser441Asn ABCG2 p.Gln126* ABCG2 p.Gly268Arg Amino acid change SNP ID dbSNP (NCBI) Exon Type of mutation Number of hyperuricemia patients Allele frequency (%) (in hyperuricemia) Allele frequency* (%) (in Japanese population) Wild-type Heterozygote Homozygote Q141K rs2231142 5 Missense 29 47 14 41.67 31.9 V12M rs2231137 2 Missense 64 23 3 16.11 19.2 Q126X 4 Nonsense 80 10 0 5.56 2.8 G268R 7 Missense 89 1 0 0.56 N.D. S441N 11 Missense 89 1 0 0.56 0.3 F506SfsX4 13 Frameshift 89 1 0 0.56 0.3 * Data from Maekawa et al. (34). Login to comment 90 ABCG2 p.Gln141Lys ABCG2 p.Gln141Lys ABCG2 p.Val12Met ABCG2 p.Gln126* Q141K was 98.8%, 100%, and 99.2%, respectively. P values for Hardy-Weinberg equilibrium of V12M, Q126X, and Q141K were 0.08, 0.72, and 0.01, respectively. P values that suggested mistyping were not obtained. Login to comment 91 ABCG2 p.Gln141Lys ABCG2 p.Gln126* Haplotype frequency analysis revealed that there is no simultaneous presence of the minor alleles of Q126X and Q141K in one haplotype (Table 3). Login to comment 92 ABCG2 p.Gln126* The haplotype with Q126X is present in up to 13.5% of gout patients, and it markedly increases gout risk (OR, 5.97; 95% CI, 3.39-10.51; P = 4.10 × 10-12 ) compared with nonrisk haplotypes. Login to comment 93 ABCG2 p.Gln141Lys Q141K is assigned to another independent risk haplotype. Login to comment 94 ABCG2 p.Gln126* Our data also show enrichment of the Q126X minor allele in gout or hyperuricemia patients relative to normouricemic subjects (SUA ≤ 7.0 mg/dl). Login to comment 95 ABCG2 p.Gln126* Thus, the Q126X mutation of the ABCG2 gene is identified as a major cause of primary gout. Login to comment 96 ABCG2 p.Gln126* Together, these findings suggest that nonfunctional variants of ABCG2, such as Q126X, essentially block urate excretion and cause gout. Login to comment 97 ABCG2 p.Val12Met ABCG2 p.Val12Met Our findings showed that V12M is exclusively assigned to a nonrisk haplotype (Table 3) and that the V12M variant does not exhibit altered urate transport activity (Fig. 2B). Login to comment 98 ABCG2 p.Val12Met These findings may help explain why V12M decreases gout risk (OR, 0.68; 95% CI, 0.49-0.94; P = 0.02) (Table 2). Login to comment 99 ABCG2 p.Gln141Lys ABCG2 p.Gln126* Because Q126X and Q141K are assigned to different risk haplotypes, nonfunctional and half-functional haplotype, respectively, their genotype combinations are divided into four groups on the basis of the estimated ABCG2 transport functions, that is, full function, ¾ function, ½ function, and ≤¼ function (Table 4). Login to comment 106 ABCG2 p.Gln126* We also demonstrated that nonfunctional ABCG2 mutation Q126X is assigned to the identical haplotype, which increases gout risk, conferring an OR of 5.97. Login to comment 115 ABCG2 p.Gln141Lys ABCG2 p.Gln141Lys ABCG2 p.Val12Met ABCG2 p.Val12Met ABCG2 p.Gln126* ABCG2 p.Gln126* Phenotype SNP Genotype* Allele frequency mode Case Control P value P value OR 95% CI 1/1 1/2 2/2 MAF 1/1 1/2 2/2 MAF Q126X 1 21 139 0.071 0 31 840 0.018 1.74 × 10-7 3.04 × 10-8 4.25 2.44-7.38 Gout Q141K 31 87 41 0.469 87 316 462 0.281 5.80 × 10-10 5.54 × 10-11 2.23 1.75-2.87 V12M 3 43 112 0.155 30 306 526 0.212 0.055 0.020 0.68 0.49-0.94 Q126X 2 24 202 0.061 0 31 840 0.018 1.91 × 10-6 2.91 × 10-7 3.61 2.14-6.08 Hyperuricemia Q141K 45 113 68 0.449 87 316 462 0.281 5.32 × 10-10 1.53 × 10-11 2.06 1.67-2.55 V12M 7 55 163 0.153 30 306 526 0.212 0.006 0.005 0.67 0.51-0.89 * Minor allele was referred to as allele 1 and major allele as 2. Login to comment 116 ABCG2 p.Gln126* Allele 1 is T and allele 2 is C in Q126X. Login to comment 117 ABCG2 p.Gln141Lys Allele 1 is A and allele 2 is C in Q141K. Login to comment 118 ABCG2 p.Val12Met Allele 1 is A and allele 2 is G in V12M. Login to comment 120 ABCG2 p.Gln141Lys ABCG2 p.Val12Met ABCG2 p.Gln126* Haplotype frequency analysis of V12M, Q126X, and Q141K. Login to comment 122 ABCG2 p.Gln141Lys ABCG2 p.Gln126* Risk alleles for Q126X and Q141K are underlined. Login to comment 123 ABCG2 p.Gln141Lys ABCG2 p.Val12Met ABCG2 p.Gln126* Allele Frequency P value OR 95% CI V12M Q126X Q141K Gout Control G C A 0.465 0.284 2.26 × 10-13 2.50 1.94-3.20 G T C 0.071 0.018 4.10 × 10-12 5.97 3.39-10.51 G C C 0.306 0.486 - - - A C C 0.155 0.212 - - - of ABCG2, such as rosuvastatin (42) and gefitinib (43), have been reported. Login to comment 137 ABCG2 p.Gln126* The approach reported here (fig. S1) revealed that nonfunctional variants of ABCG2, such as Q126X, essentially block urate excretion and cause gout. Login to comment 138 ABCG2 p.Gln126* ABCG2 p.Gln126* In contrast to the rare Mendelian disorders described above, the disease haplotype carrying the ABCG2 Q126X mutation (OR, 5.97; 95% CI, 3.39-10.51; P = 4.10 × 10-12 ) is present in as many as 13.5% of primary gout patients in our population, suggesting that Q126X is a major causative mutation for gout. Login to comment 144 ABCG2 p.Gln141Lys ABCG2 p.Gln126* OR is obtained by comparing with nonrisk genotype combination C/C(Q126X) and C/C(Q141K). Login to comment 145 ABCG2 p.Gln141Lys ABCG2 p.Gln126* Risk alleles for Q126X and Q141K are underlined. Login to comment 146 ABCG2 p.Gln141Lys ABCG2 p.Gln141Lys ABCG2 p.Gln126* ABCG2 p.Gln126* Estimated transport Genotype Number P value OR 95% CI Q126X Q141K Gout Control ≤¼ function T/T C/C 16 8 3.39 × 10-21 25.8 10.3-64.6 T/C A/C ½ function T/C C/C 37 110 2.23 × 10-9 4.34 2.61-7.24 C/C A/A ¾ function C/C A/C 72 308 2.29 × 10-7 3.02 1.96-4.65 Full function C/C C/C 34 439 Normal control UA ABCG2 transport Gout <UA 7.0 mg/dl 23.3% 10.1% 35.6% 12.7% 0.9% patients Gout no function Q126X T/T Q141K C/C 25% function 50% function =< T/C A/C 45.3% 50.8% 100% function 75% function 50% function C/C C/C T/C A/C A/A C/C 21.4%s 100% function C/C C/C Other gout risk G G G G G N G Fig. 3. Login to comment 148 ABCG2 p.Gln141Lys ABCG2 p.Gln126* The genotype combinations of Q126X and Q141K are divided into several groups based on estimated ABCG2 transport functions. Login to comment 149 ABCG2 p.Gln126* The Q126X homozygous and heterozygous mutations were identified in up to 13.5% of total gout patients (n = 161). Login to comment 154 ABCG2 p.Gln141Lys They also found that a missense SNP (Q141K) was associated with self-reported gout in Caucasians (OR, 1.74; 95% CI, 1.51-1.99) (22), which is consistent with our finding from clinically diagnosed gout patients from a Japanese population. Login to comment 156 ABCG2 p.Gln141Lys ABCG2 p.Gln126* In this study, we identified several nonfunctional ABCG2 mutations, including Q126X, in Japanese gout patients, which shows stronger effects on gout development than Q141K did in a previous study (OR < 2.0) (22). Login to comment 157 ABCG2 p.Gln126* There is a possibility that these nonfunctional mutations, including Q126X, are specific to a Japanese or Asian population, or alternatively, there may be nonfunctional mutations in the ABCG2 gene that cause gout in Caucasians and other groups. Login to comment 160 ABCG2 p.Gln141Lys We and Woodward et al. (55) independently found an ability of ABCG2 to transport urate and characterized the effects of a partially functional variant Q141K using different methods. Login to comment 172 ABCG2 p.Gln141Lys For QTL analysis of SUA concentrations, genotyping of Q141K in 739 Japanese individualswas performed. Login to comment 181 ABCG2 p.Gln141Lys ABCG2 p.Val12Met ABCG2 p.Ser441Asn ABCG2 p.Gln126* ABCG2 p.Gly268Arg Using the site-directed mutagenesis technique, we constructed mutants of ABCG2 (V12M, Q126X, Q141K, G268R, S441N, and F506SfsX4), which were used for urate transport analysis, on the expression vector for ABCG2. Login to comment 201 ABCG2 p.Gln141Lys Association of Q141K in ABCG2 with clinical parameters. Login to comment