High frequency of mutant thiopurine S-methyltransferase genotypes in Mexican patients with systemic lupus erythematosus and rheumatoid arthritis

Systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) are treated with immunosuppressive purine analogs, 6-mercaptopurine/6-thioguanine/azathiopurine, which are inactivated by thiopurine S-methyltransferase (TPMT). Non-synonymous polymorphisms in TPMT are associated with increased risk of adverse effects in patients treated with thiopurines. This study aimed to determine the frequency of the most common mutant TPMT alleles in Mexican patients with SLE (a prototype autoimmune disease) and RA (one of the most common autoimmune diseases in Mexico). Five hundred fifty-three consecutive patients from Central Mexico with SLE (178) and RA (375) were included. Subjects were genotyped to identify TPMT*2 (rs1800462), TPMT*3A (rs1800460 and rs1142345), TPMT*3B (rs1800460), and TPMT*3C (rs1142345) mutant alleles. DNA samples were assayed with the 5′ exonuclease technique and TaqMan probes. Mutant alleles were detected in 6.2 and 5.2% of SLE and RA cases, respectively. Of note, 12.4% of SLE cases and 10.1% of RA cases carried mutant genotypes. Among those, the null genotype (TPMT*2/*3A, 0.3%) and the TPMT*3B (0.5%) and TPMT*3C (1.0%) alleles were found in RA, but not SLE cases. Mexican SLE cases displayed the highest frequency of mutant TPMT genotypes worldwide. TPMT genotyping should be performed for Mexican patients with SLE and RA before prescribing purine analogs.     

Thiopurine S-methyltransferase (TPMT) Activity Is Better Determined by Biochemical Assay Versus Genotyping in the Jewish Population

Background

Thiopurine S-methyltransferase (TPMT) is a key enzyme that deactivates thiopurines, into their inactive metabolite, 6-methylmercaptopurine. Intermediate and low TPMT activity may lead to leukopenia following thiopurine treatment. The aim of this study was to determine TPMT activity and TPMT alleles (genotype–phenotype correlation) in Jews, aiming to develop an evidence-based pharmacogenetic assay for this population.

Methods

TPMT activity was determined in 228 Jewish volunteers by high performance liquid chromatography. Common allelic variants in the Caucasian population [TPMT*2 (G238C), TPMT *3A (G460A and A719G), TPMT* 3B (G460A) and TPMT*3C (A719G)] were tested. Phenotype–genotype correlation was examined and discordant cases were fully sequenced to identify novel genetic variants.

Results

Mean TPMT activity was 15.4 ± 4 U/ml red blood cells (range 1–34). Intermediate activity was found in 33/228 (14 %) subjects and absent activity was found in one sample (0.4 %). Only eight individuals (3.5 % of the entire cohort and 24 % of those with intermediate/low activity) were identified as carriers of a TPMT genetic variant, all of whom had the TPMT*3A allele. Sequencing the entire TPMT coding region and splice junctions in the remainder of the discordant cases did not reveal any novel variants.

Conclusion

Genotyping TPMT in Jews yields a much lower rate of variants than identified in the general Caucasian population. We conclude that a biochemical assay to determine TPMT enzymatic activity should be performed in Jews before starting thiopurine treatment in order to identify low activity subjects.     

Thiopurine methyltransferase and treatment outcome in the UK acute lymphoblastic leukaemia trial ALL2003

The influence of thiopurine methyltransferase (TPMT) genotype on treatment outcome was investigated in the United Kingdom childhood acute lymphoblastic leukaemia trial ALL2003, a trial in which treatment intensity was adjusted based on minimal residual disease (MRD). TPMT genotype was measured in 2387 patients (76% of trial entrants): 2190 were homozygous wild‐type, 189 were heterozygous for low activity TPMT alleles (166 TPMT*1/*3A, 19 TPMT*1/*3C, 3 TPMT*1/*2 and 1 TPMT*1/*9) and 8 were TPMT deficient. In contrast to the preceding trial ALL97, there was no difference in event‐free survival (EFS) between the TPMT genotypes. The 5‐year EFS for heterozygous TPMT*1/*3A patients was the same in both trials (88%), but for the homozygous wild‐type TPMT*1/*1 patients, EFS improved from 80% in ALL97% to 88% in ALL2003. Importantly, the unexplained worse outcome for heterozygous TPMT*1/*3C patients observed in ALL97 (5‐year EFS 53%) was not seen in ALL2003 (5‐year EFS 94%). In a multivariate Cox regression analysis the only significant factor affecting EFS was MRD status (hazard ratio for high‐risk MRD patients 4·22, 95% confidence interval 2·97–5·99, P < 0·0001). In conclusion, refinements in risk stratification and treatment have reduced the influence of TPMT genotype on treatment outcome in a contemporary protocol.     

Thiopurine-methyltransferase variants in inflammatory bowel disease:Prevalence and toxicity in Brazilian patients

AIM:To analyze the prevalence of thiopurine-methyltransferase(TPMT)genotypes and their associationwith drug toxicity in inflammatory bowel disease(IBD)patients from southeastern Brazil.METHODS:A total of 219 consecutive patients with IBD,of which 146 had Crohn’s disease and 73 had ulcerative colitis,regularly seen at the outpatient unit of the Division of Gastroenterology at the University Hospital Pedro Ernesto of the State University of Rio de Janeiro,a tertiary referral center,were enrolled in this study from February 2009 to January 2011.We analyzed the presence of major TPMT genetic variants(TPMT*2,*3A,*3C)in IBD patients by means of a specific allele and RFLP-PCR.Genomic DNA was isolated from peripheral blood leukocytes by proteinase-K/Sodium Dodecyl Sulfate digestion and phenol-chloroform extraction.TPMT*2(C238G),TPMT*3A(G460A/A719G),and TPMT*3C(A719G)genotypes were detected by real-time polymerase chain reaction followed by direct sequencing with specific primers.Clinical data were systematically recorded,and correlated with the genotype results.RESULTS:The distribution of the selected TPMT gene polymorphism TPMT*2(C238G),TPMT*3A(G460A/A719G),and TPMT*3C(A719G)genotypes was 3.6%,5.4%,and 7.7%of the patients,respectively.Among the side effects recorded from patients taking azathioprine,14 patients presented with pancreatitis and/or an elevation of pancreatic enzymes,while 6 patients had liver toxicity,and 2 patients exhibited myelosuppression/neutropenia.TPMT polymorphisms were detected in 37/219 patients(8 heterozygous for*2,11 heterozygous for*3A,and 18 heterozygous for*3C).No homozygotic polymorphisms were found.Despite the prevalence of the TPMT*3C genotype,no differences among the genotype frequencies were significant.Although no association was detected regarding myelotoxicity or hepatotoxicity,a trend towards the elevation of pancreatic enzymes was observed for TPMT*2 and TPMT*3C genotypes.CONCLUSION:The prevalence of TPMT genotypes was high among Brazilian patients.Variants genes*2and*3C may be associated with azathioprine pancreatic toxicity in a IBD southeastern Brazilian population.     

The low frequency of defective TPMT alleles in Turkish population: a study on pediatric patients with acute lymphoblastic leukemia

6-Mercaptopurine (6MP) is an essential anticancer drug used in the treatment of childhood acute lymphoblastic leukemia (ALL). Thiopurine methyltransferase (TPMT) polymorphisms are the major determinants of interindividual differences in the severe toxicity or efficacy of 6MP. Four variant alleles, TPMT*2, TPMT*3A, TPMT*3B, and TPMT*3C, are responsible over the 80% of low or undetectable enzyme activity. The frequencies of these variants were investigated among 106 children with ALL in Turkish population. TPMT*3A and TPMT*3C were the only deficiency alleles detected in Turkish population with an allele frequency of 0.9% for both. While *3C allele frequency in Turkish population was found to be very similar to Asian and other Caucasian populations, *3A allele frequency was significantly (P < 0.05) lower. So far, studies showed that the genetic polymorphisms of other drug metabolizing enzymes like CYP2E1, CYP1A1, GSTM1/ T1 in Turkish population were similar to Caucasian populations. However, we found that the distribution of TPMT polymorphisms in Turkish population was significantly lower than those in other Caucasians like British, French, and Italian whereas the distributions of TPMT variants were found to be very similar to Kazak population which is also Caucasian in ethnic origin. In this study, the clinical histories of the patients in the sample population were also examined, retrospectively. The patients with heterozygous or homozygous mutant genotypes had developed severe neutropenia and infection during 6MP therapy. The study provides the first data on the frequency of common TPMT variants in the Turkish population, based on analysis of pediatric patients with ALL.     

SDF-1alpha G801A polymorphism in Southern Iranian patients with colorectal and gastric cancers

Background

A single nucleotide polymorphism (SNP) in the stromal cell-derived factor-1 (SDF-1) gene at position 801 (G>A) is associated with susceptibility to certain tumors. This study aimed to investigate an association between this SNP and colorectal and gastric cancers in an Iranian population.

Method

Genotype and allele frequencies of SDF-1 801 G>A were assessed using polymerase chain reaction-restriction fragment length polymorphism in 109 patients with colorectal cancer, 124 with gastric cancer, and 262 normal control volunteers.

Results

No statistically significant difference was observed in the frequencies of genotypes and alleles between patients and controls (p?>?0.05).

Conclusion

SDF-1 gene polymorphism at position 801 (G>A) was not associated with colorectal and gastric cancers in Southern Iranian patients.     

Thiopurine dose intensity and treatment outcome in childhood lymphoblastic leukaemia: the influence of thiopurine methyltransferase pharmacogenetics

The impact of thiopurine methyltransferase (TPMT) genotype on thiopurine dose intensity, myelosuppression and treatment outcome was investigated in the United Kingdom childhood acute lymphoblastic leukaemia (ALL) trial ALL97. TPMT heterozygotes had significantly more frequent cytopenias and therefore required dose adjustments below target levels significantly more often than TPMT wild‐type patients although the average dose range was similar for both genotypes. Event‐free survival (EFS) for patients heterozygous for the more common TPMT*1/*3A variant allele (n = 99, 5‐year EFS 88%) was better than for both wild‐type TPMT*1/*1 (n = 1206, EFS 80%, P = 0·05) and TPMT*1/*3C patients (n = 17, EFS 53%, P = 0·002); outcomes supported by a multivariate Cox regression analysis. Poor compliance without subsequent clinician intervention was associated with a worse EFS (P = 0·02) and such non‐compliance may have contributed to the poorer outcome for TPMT*1/*3C patients. Patients prescribed escalated doses had a worse EFS (P = 0·04), but there was no difference in EFS by dose intensity or duration of cytopenias. In contrast to reports from some USA and Nordic trials, TPMT heterozygosity was not associated with a higher rate of second cancers. In conclusion, TPMT*1/*3A heterozygotes had a better EFS than TPMT wild‐type patients. Thiopurine induced cytopenias were not detrimental to treatment outcome.     

The HLA-B*3906 allele imparts a high risk of diabetes only on specific HLA-DR/DQ haplotypes

Aims/hypothesis

We investigated the risk associated with HLA-B*39 alleles in the context of specific HLA-DR/DQ haplotypes.

Methods

We studied a readily available dataset from the Type 1 Diabetes Genetics Consortium that consists of 2,300 affected sibling pair families genotyped for both HLA alleles and 2,837 single nucleotide polymorphisms across the major histocompatibility complex region.

Results

The B*3906 allele significantly enhanced the risk of type 1 diabetes when present on specific HLA-DR/DQ haplotypes (DRB1*0801-DQB1*0402: p?=?1.6?×?10^?6, OR 25.4; DRB1*0101-DQB1*0501: p?=?4.9?×?10^?5, OR 10.3) but did not enhance the risk of DRB1*0401-DQB1*0302 haplotypes. In addition, the B*3901 allele enhanced risk on the DRB1*1601-DQB1*0502 haplotype (p?=?3.7?×?10^?3, OR 7.2).

Conclusions/interpretation

These associations indicate that the B*39 alleles significantly increase risk when present on specific HLA-DR/DQ haplotypes, and HLA-B typing in concert with specific HLA-DR/DQ genotypes should facilitate genetic prediction of type 1 diabetes, particularly in a research setting.     

High-dose methotrexate in Egyptian pediatric acute lymphoblastic leukemia: the impact of ABCG2 C421A genetic polymorphism on plasma levels,what is next?

Purpose

High-dose methotrexate (HD-MTX) is a cornerstone antineoplastic drug in most treatment protocols of pediatric acute lymphoblastic leukemia (ALL). Among the membrane efflux transporters of MTX, the human breast cancer resistant protein is the second member of the G subfamily of ATP-binding cassette (ABC) efflux pump (ABCG2). A single-nucleotide polymorphism (SNP) in ABCG2, the exchange of C to A at position 421, represents 13 % in the Middle Eastern population. We studied the effect of this SNP on the plasma levels of HD-MTX in Egyptian pediatric ALL.

Methods

Two hundred ALL patients were recruited from Children’s Cancer Hospital Egypt-57357, and all were treated according to the St Jude Total XV protocol. Determination of plasma MTX levels was done at 23, 42 and 68 h. Genotyping of C421A of ABCG2 was done by polymerase chain reaction-restriction fragment length polymorphism.

Results

We found 14.5 % of the variant allele of the ABCG2 C421A SNP. The statistical association between ABCG2 421C>A SNP and the cutoff toxic plasma level of 24 h HD-MTX infusion at different time points tested was not statistically significant. There was no statistical significance between steady-state plasma concentration in patients with and without with this SNP.

Conclusion

To date, this is the largest study on Egyptian ALL patients for this SNP. This study shows that there is no effect of ABCG2 421C>A on plasma concentrations of HD-MTX. Replacing candidate gene association studies with genome-wide studies of HD-MTX is now mandatory and is part of our research blueprint.     

Enhanced proteolysis of thiopurine S-methyltransferase (TPMT) encoded by mutant alleles in humans (TPMT∗3A, TPMT∗2): Mechanisms for the genetic polymorphism of TPMT activity

TPMT is a cytosolic enzyme that catalyzes the S-methylation of aromatic and heterocyclic sulfhydryl compounds, including medications such as mercaptopurine and thioguanine. TPMT activity exhibits autosomal codominant genetic polymorphism, and patients inheriting TPMT deficiency are at high risk of potentially fatal hematopoietic toxicity. The most prevalent mutant alleles associated with TPMT deficiency in humans have been cloned and characterized (TPMT2 and TPMT3A), but the mechanisms for loss of catalytic activity have not been elucidated. In the present study, we established that erythrocyte TPMT activity was significantly related to the amount of TPMT protein on Western blots of erythrocytes from patients with TPMT activities of 0.4-23 units/ml pRBC (r_s = 0.99; P < 0.001). Similarly, heterologous expression of wild-type (TPMT1) and mutant (TPMT2 and TPMT3A) human cDNAs in yeast and COS-1 cells demonstrated comparable levels of TPMT mRNA but significantly lower TPMT protein with the mutant cDNAs. Rates of protein synthesis were comparable for wild-type and mutant proteins expressed in yeast and with in vitro translation in rabbit reticulocyte lysates. In contrast, pulse–chase experiments revealed significantly shorter degradation half-lives for TPMT2 and TPMT3A (~0.25 hr) compared with wild-type TPMT1 (18 hr). The degradation of mutant proteins was impaired by ATP depletion and in yeast with mutant proteasomes (pre-1 strain) but unaffected by the lysosomal inhibitor chloroquine. These studies establish enhanced degradation of TPMT proteins encoded by TPMT2 and TPMT3A as mechanisms for lower TPMT protein and catalytic activity inherited by the predominant mutant alleles at the human TPMT locus.     

Prevalence of TPMT polymorphism in Indian patients requiring immunomodulator therapy and its clinical significance

Background

Thiopurine methyltransferase (TPMT) enzyme plays a key role in the metabolism of azathioprine/6-mercaptopurine (6-MP). Mutations in the enzyme lead to generation of excess thioguanine, which causes suppression of various cell lineages, especially neutrophils. Data on the prevalence of TPMT polymorphism are available from Western and some Asian countries; such data from India are sparse.

Aims

The aim of this research is to study the prevalence of TPMT mutation in Indian patients requiring immunomodulator therapy and its relation to the development of neutropenia on azathioprine therapy.

Methods

In this retrospective study, data of all patients who underwent TPMT genotyping by PCR-RFLP and allele-specific PCR prior to immunomodulator therapy were analyzed. The frequency of on-treatment development of neutropenia (total neutrophil count <1,500 per cubic millimeters) was noted.

Results

Data were available on 126 patients (mean age, 42 [SD 13.6] years; 73 men and 53 women). The disease indications included ulcerative colitis (61), Crohn's disease (43), indeterminate colitis (1), autoimmune hepatitis (16), and others (5). TPMT genotype was wild in 120 patients (95.23 %) and heterozygous in 6 patients (4.77 %); no patient had homozygous mutation. Seven of 87 patients (6.8 %) who received azathioprine developed neutropenia; blood counts normalized on cessation of the drug in all. The incidence of neutropenia in patients with wild type was 6/84 (7.14 %) and with heterozygous type 1/3 (33 %) (p?=?0.5764).

Conclusion

Nearly 5 % of this population of patients requiring immunomodulator therapy was heterozygous carriers of the TPMT gene. Neutropenia was equally common in patients without and with the mutation.     

DNA repair polymorphisms influence the risk of second neoplasm after treatment of childhood acute lymphoblastic leukemia

Purpose

Patients treated for childhood acute lymphoblastic leukemia (ALL) are considered to be at increased risk of developing second neoplasm. The aim of our study was to identify DNA repair polymorphisms contributing to the risk of second neoplasm in clinically well-characterized Slovenian patients treated for childhood ALL.

Methods

Pediatric patients diagnosed with ALL between 1971 and 2001 were included in the study. According to the identified clinical risk factors for second neoplasm, a matched set of cases with second neoplasm and controls was selected and genotyped for 11 DNA repair polymorphisms.

Results

Among 359 pediatric patients with ALL, 20 second neoplasms were observed. The dose of radiotherapy (P?=?0.011), administration of epipodophyllotoxins (P?=?0.006), and the dose of anthracyclines (P?<?0.001) showed a significant association with the risk of second neoplasm. Among genetic factors, we observed a significant association of NBN 1197G allele with increased risk of second neoplasms (RR?=?4.36; 95?% CI: 1.19–15.98; P?=?0.026), while the risk was decreased in carriers of XRCC3-316G allele compared with patients with wild-type genotype (RR?=?0.20; 95?% CI: 0.04–0.99; P?=?0.049).

Conclusions

Our results suggest an important role of NBN 1197A>G and XRCC3-316A>G polymorphisms in the development of second neoplasm in patients treated for childhood ALL.     

广州地区人群中硫嘌呤甲基转移酶基因的等位基因频率及分布

目的：了解硫嘌呤甲基转移酶(Thiopurme S-methyltransferase，TPMT)基因常见的遗传多态性在广州地区人群中的分布及其频率。方法：应用聚合酶链反应-等位基因特异性扩增(PCR-ASA)和聚合酶链反应-限制性片段长度多态性分析(PCR-RFLP)对文献报道的TPMT基因中三种常见的基因突变(G238C、G460A和A719G)进行检测。结果：在我们调查的人群中只检测到A719G(TPMT／3C)，其频率为0．7％(3／392)；该突变基因在人群中以杂合子形式存在，基因型频率为1．5％(3／196)，未发现突变型纯合子，亦未检测到另外两种基因突变。结论：广州地区人群中TPMT等位基因的频率及分布与白人存在明显差异，与黑人及日本人较为接近，但频率更低。     

Pharmacogenetic distribution of warfarin and its clinical significance in Korean patients during initial anticoagulation therapy

During warfarin treatment, determining the optimal dose and maintaining the target PT-INR are challenging. Increasing evidence supports the theory that genotypic polymorphisms influence an individual’s warfarin dose requirement. In this study, we evaluated allele frequencies and effects of CYP2C9 and VKORC1 on warfarin response during initial anticoagulation therapy in Korean patients. We enrolled patients who had initiated warfarin therapy and undergone PT-INR testing at least three times within the first month of anticoagulation therapy. All the participating patients were tested for the detection of CYP2C9*3 (c.1075A>C) and VKORC1-1639G>A. A melting-curve analysis after real-time PCR was performed using CYP2C9*3 and VK1639 genotyping kits (Idaho Technology, US). A total of 37 patients were enrolled in this study. CYP2C9*1/*1 (87%) and VKORC1-1639AA genotypes (89%) were predominant in Korea. The CYP2C9*3 and VKORC1-1639G alleles were found in five (13%) and four patients (11%), respectively. Patients with the CYP2C9*3 allele received a lower warfarin dose (P = 0.018) and tended to show more rapid PT-INR increase than CYP2C9*1/*1 genotype. Patients with the VKORC1-1639G allele nonsignificantly received higher warfarin dose than those without. The CYP2C9*3 and VKORC1-1639G alleles influenced warfarin response during the first month of anticoagulation therapy. Considering these results, CYP2C9 and VKORC1 genotyping can be an useful tool to estimate initial warfarin dose and frequency of PT-INR monitoring during the first month of anticoagulation therapy.     

Association of apolipoprotein A5 gene polymorphisms and serum lipid levels

Background and aims

Apolipoprotein (APO) A5 gene polymorphisms have been associated with increased plasma triglyceride (TG), but the results are inconsistent. The present study was undertaken to detect the APOA5 gene polymorphisms and their associations with lipid profiles in the Guangxi Hei Yi Zhuang and Han populations.

Methods and results

Genotyping of the APOA5 −1131T>C, c.553G>T and c.457G>A was performed in 490 subjects of Hei Yi Zhuang and 540 participants of Han Chinese aged 15-89 years. The −1131C allele frequency was higher in high total cholesterol (TC) than in normal TC subgroups in both the ethnic groups (P < 0.05). The c.553T allele frequency was higher in high TG than in normal TG subgroups (P < 0.01), in high APOB than in normal APOB subgroups in Hei Yi Zhuang (P < 0.05), or in females than in males in Han (P < 0.01). The c.457A allele frequency in Han was higher in high TG than in normal TG subgroups, in low APOA1 than in normal APOA1 subgroups, in males than in females, or in normal APOB than in high APOB subgroups (P < 0.05-0.01). The levels of TC, low-density lipoprotein cholesterol and APOB in Hei Yi Zhuang were correlated with −1131T>C genotype or allele, and the levels of TG were associated with c.553G>T genotype (P < 0.05). The levels of TG, APOA1 and APOB in Han were correlated with c.457G>A genotype or allele, and the levels of TC were associated with −1131T>C allele (P < 0.05).

Conclusions

The differences in the lipid profiles between the two ethnic groups might partly result from different APOA5 gene-environmental interactions.     

Novel and Recurrent Mutations of STK11 Gene in Six Chinese Cases with Peutz–Jeghers Syndrome

Background

The serine/threonine kinase 11 (STK11) gene is the main causal gene in Peutz–Jeghers syndrome (PJS). Abnormal STK11 may increase cancer risk of PJS patients via affecting its target proteins such as P53, AMPK, and PTEN. In this study, we investigated the molecular basis of six Chinese PJS patients.

Materials and Methods

Blood samples were collected from four Chinese PJS families and two sporadic patients. The entire coding region of the STK11 gene was amplified by polymerase chain reaction and analyzed by direct sequencing. Functions of mutants were assessed by PolyPhen-2, Swiss-Model software, and luciferase reporter assay.

Results

Novel mutations (c.842_843insC, c.804_805insG, and c.922T>G) and recurrent mutations (c.526G>A, c.180C>G, and c.1062C>G) were identified. Missense mutation c.922T>G and c.526G>A were predicted as probably damaging by PolyPhen-2, while c.1062C>G was benign. Mutation c.108C>G was a nonsense mutation. The 284Ter mutants of c.842_843insC and c.804_805insG significantly diminished the capacity of P53 activity in 293FT cells.

Conclusions

Our results support that STK11 gene mutations underlie Chinese patients with PJS. Mutation involving partial kinase domain disrupts normal function of STK11. Our results also enlarge the spectrum of STK11 variants in PJS patients.     

Frailty Intervention Trial (FIT)

Background

While the evidence of an association between the apolipoprotein E (APOE) *E4 allele and Alzheimer's disease is very strong, the effect of the *E4 allele on cognitive decline in the general population is more equivocal. A cross-sectional study on the lifespan effects of the *E4 allele [1] failed to find any effect of the *E4 allele on cognitive performance at ages 20–24, 40–44 or 60–64 years.

Methods

In this four year follow-up study, we reexamine the effect of *E4 in the sample of 2,021 individuals, now aged 65–69 years.

Results

Performance on the Mini-Mental State Examination (MMSE) was significantly poorer for *E4 homozygotes than heterozygotes or non-carriers. The effects of the *E4 genotype on cognitive decline over four years were found on the MMSE and Symbol-Digit Modalities test but only when controlling for risk factors such as head injury and education. Analyses were repeated with the exclusion of participants diagnosed with a mild cognitive disorder, with little change.

Conclusion

It is possible that *E4 carriers become vulnerable to greater cognitive decline in the presence of other risk factors at 65–69 years of age.     

Genetic differences between type 1 diabetes with and without other autoimmune diseases

Background

Clusters of autoimmune diseases (ADs) are present in some people with type 1 diabetes. This clustering suggests the existence of common genetic backgrounds for abnormal autoimmunity in these individuals. However, the genetic differences between type 1 diabetes patients with and without other ADs are not well known.

Methods

To investigate the clinical background and genetic differences between type 1 diabetes patients with and without other ADs, single nucleotide polymorphisms (SNPs) in the CTLA4, SUMO4, PTPN22, IRF5, STAT4, and BLK genes were analysed by using either a TaqMan assay or direct sequencing. The frequencies of alleles, genotypes of each gene, and the human leukocyte antigen (HLA) haplotype were analysed to investigate differences among 3 groups: type 1 diabetes with systemic ADs (group A), type 1 diabetes with other organ‐specific ADs (group B), and type 1 diabetes without other ADs (group C).

Results

The frequency of the C allele in the ‐1123G > C SNP in the PTPN22 gene promoter was significantly higher in groups A and B than in group C (P = .0258 and .0207, respectively). The allele frequencies of the other SNPs were comparable. The frequency of HLA DRB1*0405‐DQB1*0401 was significantly higher in groups A and B than in group C (P = .021 and .0395, respectively).

Conclusions

The ‐1123G > C SNP in the PTPN22 gene promoter and HLA DRB1*0405‐DQB1*0401 might influence the concurrence of systemic and organ‐specific ADs in patients with type 1 diabetes.     

Clopidogrel Pharmacogenetics in Iranian Patients Undergoing Percutaneous Coronary Intervention

Clopidogrel is used in patients with coronary syndromes and at risk of thrombotic events or receiving percutaneous coronary intervention (PCI) for reducing heart attack and stroke. Here we present genotype and phenotype study of Iranian patients undergoing PCI treated with clopidogrel during a 6-month period of follow-up; common variants of CYP2C19, CYP3A5, CYP3A4, and ABCB1 genes were determined as well as the patients’ cardiovascular outcomes to find out the effect of these variants individually and in combination. 388 individuals receiving PCI were enrolled in this study. Different pretreatment doses of clopidogrel were prescribed under the interventional cardiologists’ guidance. The patients were followed for a duration of 1 month, and 6 months. Six SNPs were selected for genotyping including CYP2C19*2 (c.681G?>?A), CYP2C19*3 (c.636G?>?A), CYP2C19*17 allele (c.?806C?>?T), ABCB1 (c.3435C?>?T), CYP3A5 (c.6986A?>?G), and CYP3A4 (c.1026?+?12G?>?A). The mean loading dose was 600 mg/day in 267 (68.8%) individuals, 300 mg/day in 121 (31.2%). 8 patients had cardiovascular events such as thrombosis, unstable angina, and non-STEMI. The studied alleles and genotypes were in Hardy–Weinberg equilibrium. None of the SNPs individually were significantly associated with outcome events. Our results indicate that combinations of different alleles of genes are involved in pharmacokinetic variability and joint factors are important; this means that genotyping and analysis of an individual variant may not be as straightforward in risk assessment and pharmacogenetics. This highlights the importance of personalized medicine in risk assessment and treatment.     

Monitoring peripheral blood CD4+ adenosine triphosphate activity after living donor liver transplantation: impact of combination assays of immune function and CYP3A5 genotype

Background

The immune response after living donor liver transplantation (LDLT) was evaluated, with specific attention focused on the inter-relationship among clinical conditions, pharmacokinetics of tacrolimus, and cytochrome P450 3A5 (CYP3A5) genotypes.

Methods

Forty 40 adult patients who underwent LDLT in the period 2002?C2009 were enrolled in the study. Peripheral blood was collected from these patients between June 2009 and December 2009 and analyzed for CD4+ adenosine triphosphate (ATP) activity (ImmuKnow assay), tacrolimus concentration, and CYP3A5 genotype. Based on the results of the ImmuKnow assay (i.e., strength of immune response), each patient was categorized into one of the three established zones of immune response: Group A (low response, n?=?13), Group B (moderate response, n?=?24), and Group C (strong response, n?=?3).

Results

There was no correlation between the concentration of tacrolimus and ATP levels in the blood. The patients in Group A required much higher tacrolimus doses to maintain the blood concentration, as evidenced by the tacrolimus concentration/dose (C/D) ratios in Group A being significantly lower than those in Group B. Almost half of the patients in Group A suffered from infectious complications. The C/D ratios were significantly lower in the six patients with the CYP3A5*1 allele than in the 14 patients with the CYP3A5*3 allele; one-half of the patients with the CYP3A5*1 allele belonged to Group A.

Conclusions

Our results demonstrate that the immunKnow assay of immune function is an excellent tool for monitoring immune response, especially in the patients with CYP3A5*1 allele (expressors).