MTHFR and SLCO1B1 Gene Polymorphism and Methotrexate Induced Toxicity in Children with Acute Lymphoblastic Leukemia in the Northwest of Mexico

Introduction. Acute lymphoblastic leukemia (ALL) represents approximately 52% of pediatric cancer diagnoses in Mexico and is the leading cause of death by disease among children of 5 to 14 years. The use of pharmacogenomics for the detection of germline genetic variations, which are associated with sensitivity or toxicity to chemotherapy, is one of the recent strategies to improve survival. Some mutations present in genes related to the metabolism or transport of methotrexate (MTX) have been associated with the occurrence of toxicities during treatment in pediatric acute lymphoblastic leukemia. The effect of the SNP´s rs1801131, rs1901133 in the MTHFR and rs4149058, rs4149081 in the SLCO1B1 gene have not been studied in Northwest Mexican children with acute lymphoblastic leukemia. Patients and methods. Eligible patients were infants less than 1 year to adolescents less than 18 years of age, diagnosed with B-ALL at the Specialties Children's Hospital of Chihuahua, Mexico. Patients were treated according to the locally protocols based on the St. Jude Children's Research Hospital Total XIIIB and Total XV protocols. We followed-up for two to four weeks after 24 hours high dose MTX (1 to 5 g/m 2) administration. Toxicity data were collected objectively from the patient's medical files and adverse effects were classified as a dichotomous variable yes/no. Genomic DNA was extracted with the Master Pure DNA purification kit (Epicentre Illumina® Company) from peripheral blood. Genotyping assays were performed by real-time polymerase chain reaction, using rhAMp® IDT® genotyping probes (Iowa, USA) and Quant Studio 3 Applied Biosystems Real-Time System Thermal Cycler (Thermo Fisher Scientific®). For statistical analysis association between MTX dose, presence of toxicity, and genetic polymorphisms was evaluated by the chi-square or Fisher's exact test. The effect sizes of the associations were estimated by the OR's from univariate logistic regressions and multivariate logistic regressions to account for the possible confounding effect of sex and age. Analyses were performed by using SAS System and IBM SPSS Statistics Base 22.0 software. Results. The study population demographics and clinical characteristics are summarized in Table 1. MTHFR and SLCO1B1 genotype in our patients and controls obtained from the 1000 Genomes Project database are shown in table 2. In general, a predominance of toxicity events is observed in patients heterozygous for both polymorphisms in the MTHFR gene, but not in the SLCO1B1 gene (Figure 1). Through a logistic regression analysis, we observed an association of 8% between the polymorphisms rs1801131, rs1901133, rs4149058, rs4149081 and the presence of anemia. The AC heterozygous of the rs1801131 has the strongest association with a positive coefficient (+1.1355) and when comparing AC heterozygotes with CC mutated homozygotes, an Odds Ratio (OR) of 4.64 (CI: 95%, 0.719) was observed, identifying it as a risk factor. In contrast, the homozygous AA of the same gene, presented a negative coefficient (-0.7354), thus decreasing the probability of presenting anemia in this population. The presence of neutropenia was associated in 25% with the polymorphisms rs1801131, rs1901133, rs4149058, rs4149081. The AA homozygous of rs1801131 decreased the probability of developing neutropenia (coefficient -0.7643, p=0.04) and the TC heterozygous of rs4149056 increased the probability when comparing with the wild TT homozygotes (OR of 2.91, CI: 95%, 0.496). Liver enzymes elevation was associated in 84% with the polymorphisms rs1801131, rs1901133, rs4149058, rs4149081. We found that the presence of TC heterozygote of rs4149056 decreased the probability of hepatotoxicity (coefficient -1.5718, p=0.03) and GA heterozygote of rs41419081 increased it (coefficient +3.2056, p=0.004) (Table 3). According to this statistical model, we could not analyze the association between the polymorphisms rs1801131, rs1901133, rs4149058, rs4149081 and thrombocytopenia, mucositis, febrile neutropenia or creatinine elevation. Conclusion Toxicity related to treatment is one of the most important causes of death among pediatric ALL patients in Mexico, the development of precision medicine through the identification of SNPs associated with the variability in our patients' response is an alternative to minimize methotrexate toxicity and maximize its benefit during its use. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

Prevalence of protective haplotypes of the SLCO1B1 gene for statin transport in Mexican populations

Aim: To evaluate the genetic distribution of the rs4149056 and rs2306283 variants in the SLCO1B1 gene in Mexican Mestizo (admixed) and Native American groups. Materials & methods: We recruited 360 volunteers who were qPCR-genotyped with TaqMan probes. Results: Allele and genotype frequencies are reported. Among the expected rs4149056– rs2306283 haplotypes, T–A (42.35–58.47%) was the most prevalent which relates to the normal activity of the OATP1B1 transporter. This was followed by the T–G haplotype associated with further statin transport and cholesterol reduction (32.49–43.76%). Conclusion: Based on these SLCO1B1 gene variants, we confirmed that a minimum fraction of the Mexican study populations would be at risk from decreasing simvastatin transport and the development of statin-induced myopathy.

ABCB1 and SLCO1B1 gene polymorphisms predict methotrexate-resistant for low-risk gestational trophoblastic neoplasia

Aim: The aim of this study was to explore the effects of ABCB1 and SLCO1B1 gene polymorphisms and the methotrexate (MTX) treatment response in patients with low-risk gestational trophoblastic neoplasia (GTN). Materials & methods: Low-risk GTN patients who received MTX as a first-line single agent were enrolled. DNA was extracted from peripheral blood samples from 18 patients and assessed for ABCB1 C3435T and SLCO1B1 T521C. Results: ABCB1 C3435T and SLCO1B1 T521C polymorphisms were not associated with the MTX response or toxicity in Thai patients Conclusion: The selected ABCB1 and SLCO1B1 polymorphism do not predict the risk of MTX resistance in low-risk GTN.

SLCO1B1 Gene Polymorphisms (rs2306283 and rs4149056) and Statin-Induced Myopathy in Jordanian Diabetics

Background: The use of statins to lower high serum cholesterol levels may be associated with a number of adverse reactions, including severe myopathy. The solute carrier organic anion transporter 1B1 (SLCO1B1) gene, which encodes the organic anion-transporting polypeptide OATP1B1 is related to the intracellular transport of statins. The aim of this research is to study the association of rs2306283 and rs4149056 genetic polymorphism of SLCO1B1 gene with the development of statin-induced myopathy in Jordanian diabetics receiving statins. Methods: We included 413 patients attending the Diabetes Clinics of the National Center for Diabetes, Endocrinology and Genetics), Amman, Jordan. The study was approved by the Institutional Review Board of NCDEG. Myopathy was defined as elevation of creatine kinase more than 3 times the upper limit of normal. Every subject signed an informed consent form and donated 3-5 mL of venous blood. Genome DNA was extracted from lymphocytes of peripheral blood. Genotypes were identified using Tetra Amplification Refractory Mutation System of SLCO1B1. Results: The minor allele frequencies of rs2306283 [G] and rs4149056 [C] were 0.38 and 0.23, respectively. The two SNPs followed the Hardy-Weinberg equilibrium. The development of SIM was significantly associated with the homozygous and heterozygous minor allele genotype of rs4149056 (CC and CT), and the homozygous wild type allele genotype of rs2306283 (AA). There was no linkage disequilibrium between the two SNPs the studied subgroups. Conclusions: Genetic polymorphism in the SLCO1B1 Gene is a risk factor for the development of SIM in Jordanian patients.

The SNPs rs429358 and rs7412 of APOE gene are association with cerebral infarction but not SNPs rs2306283 and rs4149056 of SLCO1B1 gene in southern Chinese Hakka population

Background: Apolipoprotein E (ApoE) and solute carrier organic anion transporter family member 1B1 (SLCO1B1) are involved in regulating lipid metabolism. However, the relationship between genetic polymorphisms of APOE and SLCO1B1 and cerebral infarction (CI) remains unclear. Methods: A total of 938 CI patients and 1,028 control participants were included in the study. The single nucleotide polymorphisms (SNPs) rs429358 and rs7412 of the APOE gene and SNPs rs2306283 and rs4149056 of the SLCO1B1 gene were analysed by fluorescence polymerase chain reaction (PCR). Results: The genotype ɛ3/ɛ3 was the most common APOE genotype, with ɛ3 being the allele with the highest frequency, followed by ɛ4 and ɛ2. Statistically significant differences of genotype ɛ2/ɛ2 ( c 2 =3.866, P =0.049), ɛ2/ɛ3 (c 2 =20.030, P <0.001), ɛ3/ɛ4 (c 2 =16.960, P <0.001), and ɛ4/ɛ4 (c 2 =4.786, P =0.029) between CI patients and controls were detected. The SLCO1B1 genotype *1b/*1b and haplotype *1b showed the highest frequency in the study sample. There was no statistically significant difference in the frequencies of SLCO1B1 genotypes and haplotypes among CI patients comparing with controls. Moreover, ε4 carriers had significantly higher low-density lipoprotein-cholesterol (LDL-C) and apolipoprotein B (Apo-B) and lower apolipoprotein A1 (Apo-A1)/Apo-B levels than ε2 and ε3 carriers, but ε2 carriers showed lower LDL-C and Apo-B and higher Apo-A1/Apo-B than ε3 and ε4 carriers. Further, logistic regression analysis revealed that high LDL-C, high ApoB, smoking, hypertension and the ε4 allele were risks for the presence of CI. Conclusions: This study indicated that the APOE SNPs rs429358 and rs7412 may be associated with susceptibility to cerebral infarction in southern Chinese Hakka population.