N-乙酰基转移酶2基因多态性与柳氮磺吡啶药物效应的相关性

<正>N-乙酰基转移酶2(N-acetyltransferase 2,NAT2)是柳氮磺吡啶(sulfasalazine,SASP)在人体内乙酰化代谢的关键酶。NAT2基因编码区的单核苷酸多态性可以造成氨基酸序列变化,进而影响酶含量[1]或活性[2],并对相关药物的代谢产生影响。近年来,NAT2编码基因的多态性与SASP药物效应的相关性备受关注,现将目前的研究进展综述如下。     

人谷胱甘肽S-转移酶P1基因及其人群多态性

人类细胞质谷胱甘肽Ｓ转移酶(ｈＧＳＴｓ)超基因家族主要包括4个家族:Ａ、Ｍ、Ｔ、Ｐ(按旧命名系统分别为α、μ、θ、π)[1],其中ＧＳＴＭ1以及ＧＳＴＴ1的人群多态性以及与疾病易感性关系的研究开展较早,也有了一定的积累[2～4]。ＧＳＴＰ1的人群多态性问题则是近年来才引起医学界的注意。ｈＧＳＴＰ1是ｈＧＳＴｓ家族中酸性同工酶Ｐ1(有些文献中命名为ＧＳＴπ)的编码基因。1989年Ｂｏａｒｄ等人分离了人类ＧＳＴＰ1基因的ｃＤＮＡ克隆,将其定位于染色体的11ｑ13,并首次报道了ＧＳＴＰ1基因的外显子5(ＩＣｅ105→Ｖａｌ)和外显子6(Ａｌａ…     

N-乙酰基转移酶2(NAT-2)基因型与表型分析

目的:分析炎症性肠病(IBD)患者NAT-2基因型与表型,并探讨两者之间的一致性。方法:71例IBD患者提取DNA,用PCR-RFLP法分析基因型,随机选取20名IBD患者,通过服用磺胺二甲嘧啶,测尿中代谢物的吸光光度值,用比色法确定表型。结论:NAT-2基因型与表型结果吻合率高,基因型可预测表型。     

颅骨锁骨发育不全家系基因多态性与表型关系的研究

目的研究家族性颅锁骨发育不全家系基因型与临床表型的关系。方法提取临床收集的一个先天性颅锁骨发育不全家系中患者和健康成员外周血基因组DNA,PCR扩增RUNX2/CBFA1基因7个编码外显子及其侧翼内含子序列,分别进行正反向测序,对发现的突变位点行酶切分析验证。结果家系中两位患者（先证者及其父亲）显示cDNA 346T→A的杂合突变,使编码的色氨酸变成精氨酸（W 116R）,属错义突变。酶切结果进一步证实了该错义突变。测序还发现先证者父亲cDNA 198G→A的杂合突变,致第66位氨基酸的密码子GCG被GCA取代,但二者均编码丙氨酸,属同义突变。先证者及家系健康成员中未见此改变。结论 RUNX2/CBFA1基因346T→A杂合突变是该家系发病的分子基础。     

蒙古族与汉族人群GSTM3及CYP1A1基因多态性的研究

目的研究内蒙古地区蒙、汉族人群GSTM3和CYP1A1 Exon7基因多态性。方法采用聚合酶链式反应-限制性片断长度多态性（PCR-RFLP）和等位基因特异性扩增（ASA）技术分析内蒙古地区412例健康蒙古族人和436例健康汉族人的GSTM3及CYP1A1 Exon7基因多态性及基因型分布频率。结果内蒙古地区蒙、汉族人群GSTM3基因型之间的分布频率具有显著性差异（P〈0.05）,CYP1A1 Exon7基因型分布频率无显著性差异（P〉0.05）。结论 GSTM3基因型频率在内蒙古地区健康蒙、汉族人群中的分布具有显著差异,而CYP1A1 Exon7基因型分布频率无显著性差异。     

中国人群N—乙酰转移酶多态性的基因分析

AIM: To study the genetic basis of N-acetylatransferase polymorphism in Chinese. METHODS: Genotypes in 120 healthy Han volunteers from 19 provinces of China were assayed. The 3 common mutant alleles (M1, M2, M3) and one normal wild-type (WT) allele of the N-acetyltransferase (NAT2) gene were detected by allele-specific polymerase chain reaction technique. RESULTS: The NAT2 allele frequencies in 120 Chinese (WT = 0.625, M1 = 0.0458, M2 = 0.188, M3 = 0.142) were different (P < 0.01). The NAT2 genotype distribution for all detected combinations of NAT2 alleles in 120 Chinese subjects was consisitent with Hardy-Weinberg equilibrium (chi 2 = 7.27, nu = 8, 0.7 > P > 0.5). Fifty subjects (41.7%) were homozygous wildtypes, 50 subjects (41.7%) were heterozygous mutants, and 20 subjects (16.7%) were homozygous mutants. CONCLUSION: The lower frequency of mutant M1 allele compared with that of Caucasians explains the low frequency of slow acylators in Chinese.     

药物代谢酶N-乙酰基转移酶2的研究进展

NAT2是人体内重要的药物代谢酶,参与20多种肼类化合物及致癌性芳香胺和杂环胺类化合物的生物激活和灭活代谢,NAT2基因编码区的多态性造成氨基酸序列的变化,进而影响酶的活性。在此对NAT2的基因多态性、基因型分型方法以及NAT2多态性在药物代谢和新药临床研究中的意义等进行了综述。     

GSTM1基因多态性与满族人群肺癌易感性关系

目的 研究内蒙古地区GSTM1基因多态性与满族人群肺癌易感性关系.方法 采用多重PCR分析技术对内蒙古地区214例正常满族人及128例满族肺癌患者进行GSTM1基因多态性检测,并联合吸烟状况,分析GSTM1基因多态性及吸烟与肺癌之间的相互关系.结果 ①与GSTM1(+)基因型相比,携带GSTM1(-)基因型的个体患肺癌的危险度升高2.264倍;②吸烟人群较不吸烟人群患肺癌的危险度升高2.143倍;③与携带GSTM1(+)的非吸烟者相比,携带GSTM1(-)吸烟者患肺癌的危险度升高,OR值为5.504(95％ CI=2.837～10.676),且结果具有统计学意义(P＜0.001);携带GSTM1(-)的非吸烟者与携带GSTM1(+)的吸烟者患肺癌的危险度均升高,OR值分别为1.546 (95％ CI=0.771～3.100)和1.154(95％ CI=0.572～2.327),但结果没有显著性差异(P＞0.05).结论 GSTM1(-)、吸烟为内蒙古地区满族人群肺癌的易感因素.     

Polymorphism of N-acetyltransferase 1 and correlation between genotype and phenotype in a Thai population

Objectives To analyze the common allele frequencies of the arylamine-N-acetyltransferase 1 (NAT1) and examine the relationship between genotype and phenotype in a Thai population.Methods Peripheral blood samples from 233 Thai individuals were analyzed for genotype using polymerase chain reaction with restriction fragment-length polymorphism assays and for phenotype by determination of NAT1 enzyme kinetics in leukocytes using para-aminobenozic acid as a specific substrate.Results Of 466 NAT1 alleles assayed, the frequency of the NAT1*4 allele (wild-type) was 0.504 (95%CI 0.458–0.551) and those of the NAT1*10, *3 and *11 alleles were 0.438 (0.392–0.484), 0.034 (0.02–0.055) and 0.024 (0.012–0.042), respectively. Neither NAT1*14A nor *14B alleles were found in this studied population. The activity of NAT1 enzyme from peripheral blood leukocytes determined in 47 subjects was found to vary widely. The intrinsic clearance and V_max values of NAT1 enzymes with genotypes NAT1 *4/*4, *10/*10 and *4/*10 were not significantly different.Conclusion The frequency distribution of the major NAT1 alleles in the Thai population has a similar pattern to some Asian populations; however, racial differences among Asian populations need further clarification.     

类风湿关节炎与IL-1RAP基因多态性关联的研究

目的 探索IL-1RAP基因多态性与类风湿关节炎(RA)的关联性.方法 选取178例RA患者(RA组)及207例正常对照的全血标本,提取DNA、基因分型,对病例组与对照组IL-1RAP rs766442的等位基因频率、基因型进行分析.结果 IL-1RAP rs766442基因型包括GG、GT、TT,RA组与正常对照组间三种基因型频率差异有统计学意义(P=0.038)、等位基因频率差异有统计学意义(P=0.018).结论 携带T等位基因的RA患者出现RF-IgG阳性的几率可能较高,IL-1RAP rs766442的TT基因型可能为RA的易感基因.     

N-acetyltransferase 2 (Nat2) polymorphism in the sand rat Psammomys obesus

Human arylamine N-acetyltransferase 1 (NAT1) and its homologue in rodents (Nat2) are polymorphic xenobiotic metabolizing enzymes and also seem to play a role in endogenous metabolism. NAT1 and Nat2 polymorphism was associated to cancers under xenobiotic procarcinogens metabolism as well as under endogenous substrate metabolism. This study investigated the p-aminobenzoic acid (PABA) -Nat2 catalytic activity and its polymorphism in liver homogenates of adult sand rats Psammomys obesus Cretzschmar, 1828. These Saharian sand rats develop high incidence of spontaneous cancers under standard laboratory diet. The average value of PABA-Nat2 specific activity tested in nine sand rats was significant (2.96?±?2.16 nmoles/min/mg). The N-acetylation exhibited a bimodal distribution. There was a significant difference (p?<?0.01) between PABA-Nat2 activity in the fast acetylators group (4.10?±?1.67 nmol/min/mg) and slow acetylators group (0.7?±?0.27 nmol/min/mg). The percentage of the fast acetylator group was 66.66%. These results support the presence of Nat2 polymorphism in the liver of the strain sand rats Psammomys obesus. This strain is useful for investigating the role of Nat2 polymorphisms in susceptibility to cancers related to arylamine carcinogen exposures as well as to endogenous substrate metabolism.     

Correlation between genotype and phenotype of the human arylamine N-acetyltransferase type 1 (NAT1)

Arylamine N-acetyltransferase 1 (NAT1) conjugates several aromatic amines and their N-hydroxylated metabolites by N- or O-acetylation. NAT1 genotype and phenotype is known to be variable in human populations. In this study, we set out to measure the functional relevance of the frequent NAT1 gene variants for the activity in human red blood cells. Healthy German volunteers (N = 314) were genotyped for NAT1 alleles *3, *4, *10, *11, *14, and *15 using polymerase chain reactions and restriction fragment length pattern analysis, and NAT1 enzyme kinetic parameters were measured in a subset of 105 individuals using p-aminobenzoic acid as specific substrate. There was no functional difference between NAT1 alleles *4 and *10. In particular, there was no trend of increasing activity from NAT1*4/*4 to *4/*10 and *10/*10. Carriers of the NAT1 *11 and *14 alleles had a statistically significant lower enzyme activity compared with carriers of the *3, *4, or *10 alleles. Compared with the wild-type genotype NAT1*4/*4, activity of the NAT1*11/*11, NAT1*11/*10, and NAT1*11/*4 genotypes was reduced by 20.7%, 35.7%, and 31.5%, respectively. Activity of the NAT1*10/*14 and NAT1*4/*14 genotypes was reduced by 49.8% and 55.6%, respectively. The difference in NAT1 activity between the *4/*11 and *4/*14 genotypes was also significant (P < 0.01). The carrier of the NAT1*15/*15 genotype had no detectable enzyme activity. In conclusion, functional consequences of NAT1 mutations were tested in a large population. Activity in carriers of NAT1 alleles *3, *4, and *10 did not differ, alleles NAT1*11 and *14 appeared to be low activity alleles, and allele NAT1*15 had no activity.     

尿苷二磷酸葡糖醛酸基转移酶1家族肽A基因多态性与伊立替康所致不良反应的相关性研究

目的探讨尿苷二磷酸葡糖醛酸基转移酶1家族肽A（UGT1A）基因多态性与抗肿瘤药伊立替康所致不良反应的相关性,为肿瘤患者个体化用药提供参考。方法研究对象为233名健康志愿者和196例应用伊立替康治疗的肿瘤患者。健康志愿者中男性169名,女性64名;平均年龄（25±5）岁。肿瘤患者中肠癌92例,宫颈癌45例,卵巢上皮细胞癌 59例;男性54例,女性142例;平均年龄（61±19）岁。采用焦磷酸测序法对2组受试者进行UGT1A1＊6、UGT1A1＊28、UGT1A3＊1、UGT1A3＊2、UGT1A3＊3、UGT1A3＊4 和UGT1A9＊22基因多态性检测,比较2组受试者UGT1A基因型突变频率,比较不同UGT1A基因型患者迟发性腹泻和白细胞和/或中性粒细胞减少发生率,采用Logistic 回归方法分析伊立替康致不良反应的危险因素,结果以相对危险度（OR）及95%置信区间表示。结果肿瘤患者UGT1A3＊2基因型突变频率明显低于健康志愿者（50.3%比68.5%,P=0.014）,而UGT1A3＊3基因型突变频率明显高于健康志愿者（26.0%比6.2%, P=0.001）。196例肿瘤患者Ⅱ～Ⅳ度迟发性腹泻发生率为48.5%（95例）,Ⅲ～Ⅳ度迟发性腹泻发生率为11.2%（22例）;Ⅲ～Ⅳ度中性粒细胞减少发生率为49.0%（96例）。UGT1A1＊28位点野生型纯合子（WW）基因型携带者Ⅱ～Ⅳ度和Ⅲ～Ⅳ度迟发性腹泻发生率均明显低于突变型杂合子（WM）＋突变型纯合子（MM）基因型携带者［Ⅱ～Ⅳ度：40.4%（57/141）比69.1%（38/55）,P=0.006;Ⅲ～Ⅳ度：5.7%（8/141）比25.5%（14/55）,P=0.001］;UGT1A9＊22位点WW基因型携带者Ⅱ～Ⅳ度迟发型腹泻发生率明显低于WM＋MM基因型携带者［26.2%（17/65）比47.6%（40/84）,P=0.006;26.2%（17/65）比51.1%（24/47）, P=0.0057］,未发现不同基因型患者之间Ⅲ～Ⅳ度中性粒细胞减少发生率差异存在统计学意义。Logistic回归分析显示UGT1A基因型与迟发性腹泻的发生相关（OR=5.657,95%置信区间为4.782～7.245,P=0.039）。结论UGT1A1＊ 28 和UGT1A9＊ 22基因多态性可增加伊立替康所致迟发性腹泻的风险。     

Correlation between N-acetyltransferase activities in uroepithelia and in vivo acetylator phenotype.

The relationship between in vivo acetylator phenotype of individuals and N-acetyltransferase (NAT) activity in the cytosol of their cultured uroepithelia was examined in four urology patients. In vivo acetylator phenotypes were assigned by determining the ratio of N-acetyl vs. total [N-acetyl+free] sulfamethazine in urine and blood following a single oral dose (1 gm) of sulfamethazine. From the same patients, a surgical specimen of the ureter was obtained, uroepithelial cells were cultured in vitro, and the cytosols prepared. NAT activities were determined by measuring the amount of 4-acetylaminobiphenyl formed from incubation of uroepithelial cytosol with the substrate, 4-aminobiphenyl, and the cofactor [14C]acetyl coenzyme A. The two individuals phenotyped as "slow acetylators" by the in vivo method had NAT activities of 8.3 and 16.2 pmol 4-acetylaminobiphenyl/mg protein/min. In contrast, the two individuals phenotyped as "rapid acetylators" showed activities of 50.9 and 109.5 pmol 4-acetylaminobiphenyl/mg protein/min. The rapid acetylators exhibit about 6-fold greater uroepithelial NAT activities than slow acetylators, thus showing a direct correlation between the NAT activity in the uroepithelium, the target tissue of the human bladder carcinogen 4-aminobiphenyl, and the in vivo acetylator phenotype. These results imply that susceptibility of individuals to arylamine-induced bladder cancer might be associated with NAT activities in their target cells and that in vivo acetylator phenotyping could serve as a useful and relevant biochemical screening marker to assess the risk of developing bladder cancer.     

Inactivation of human arylamine N-acetyltransferase 1 by the hydroxylamine of p-aminobenzoic acid

Human N-acetyltransferase 1 (NAT1) is a widely distributed enzyme that catalyses the acetylation of arylamine and hydrazine drugs as well as several known carcinogens, and so its levels in the body may have toxicological importance with regard to drug toxicity and cancer risk. Recently, we showed that p-aminobenzoic acid (PABA) was able to down-regulate human NAT1 in cultured cells, but the exact mechanism by which PABA acts remains unclear. In the present study, we investigated the possibility that PABA-induced down-regulation involves its metabolism to N-OH-PABA, since N-OH-AAF functions as an irreversible inhibitor of hamster and rat NAT1. We show here that N-OH-PABA irreversibly inactivates human NAT1 both in cultured cells and cell cytosols in a time- and concentration-dependent manner. Maximal inactivation in cultured cells occurred within 4 hr of treatment, with a concentration of 30 μM reducing activity by 60 ± 7%. Dialysis studies showed that inactivation was irreversible, and cofactor (acetyl coenzyme A) but not substrate (PABA) completely protected against inactivation, indicating involvement of the cofactor-binding site. In agreement with these data, kinetic studies revealed a 4-fold increase in cofactor K_m, but no change in substrate K_m for N-OH-PABA-treated cytosols compared to control. We conclude that N-OH-PABA decreases NAT1 activity by a direct interaction with the enzyme and appears to be a result of covalent modification at the cofactor-binding site. This is in contrast to our findings for PABA, which appears to reduce NAT1 activity by down-regulating the enzyme, leading to a decrease in NAT1 protein content.     

N-acetyltransferase polymorphism. Comparison of phenotype and genotype in humans

N-Acetyltransferase (NAT) isoenzymes are encoded at two loci. One locus encodes an NAT which is expressed widely in tissues, does not vary amongst human individuals and is termed monomorphic NAT (mNAT). The second locus encodes an NAT which is termed polymorphic NAT (pNAT), has a distinct tissue distribution and is responsible for the difference in ability between individuals in acetylating certain arylamine (e.g. sulphamethazine) and hydrazine (e.g. isoniazid) drugs which are polymorphic substrates. We describe a simple DNA based method for genotyping individuals for pNAT. The 'fast' NAT allele (F1) and the three 'slow' alleles (S1, S2 and S3) can be distinguished by using PCR with oligonucleotide primers specific for pNAT followed by restriction enzyme digestion of the amplified product. Heterozygotes are easily identified. The genotype of individual Caucasians compares well with the extent of acetylation of sulphamethazine. The allele distribution of the Caucasian population described here differs from that reported after Southern blot analysis of a Japanese population (Deguchi et al., J Biol Chem 265: 12757-12760, 1990). The most frequent allele at the polymorphic nat locus in Caucasians, S1, is absent in the Japanese population. This difference between the two populations is likely to be the basis of the known interethnic variation in acetylator phenotype frequencies.     

足月新生儿黄疸与维生素D及NADSYN1基因多态性的相关性研究

目的 研究足月新生儿黄疸、维生素D(VD)水平及NADSYN1基因rs12785878位点单核苷酸多态性（SNP）间的关系。方法 回顾性分析216例患有黄疸的足月新生儿的临床资料,利用液相色谱-串联质谱法（LC-MS/MS）检测血清VD水平,高分辨熔解曲线（HRM）分析NADSYN1基因rs12785878位点SNP。以患儿是否>14 d分组并分别分析高胆红素血症的影响因素。结果 对于≤14 d患儿,感染、剖宫产、母乳喂养为高胆红素血症发生的危险因素;对于>14 d患儿,感染、低血浆蛋白为高胆红素血症发生的危险因素。建立的rs12785878位点HRM方法扩增反应良好,GG、GT、TT基因型区分明显。高胆组患儿携带GG基因型、G等位基因的比例更高。≤14 d患儿,TT基因型新生儿VD水平高于GG基因型新生儿[（12.61±5.23）μg/L vs.(9.62±4.24)μg/L,P<0.05]。结论 NADSYN1基因rs12785878位点GG基因型为高胆红素血症、≤14 d新生儿低VD水平的危险因素,可作为足月新生儿高胆红素血症诊治的新参考。     

Genetic analysis of N-acetyltransferase polymorphism in a Chinese population

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