Association analysis of three ABCB1 (MDR1) gene variants (C1236T, G2677A/T and C3435T) and their genotype/haplotype combinations with the familial Mediterranean fever

Genetic variations in ABC transporter genes as a predictive biomarker for toxicity in North Indian lung cancer patients undergoing platinum-based doublet chemotherapy

ATP-binding cassette (ABC) transporters are expressed in various human tissues and play a vital role in the efflux of various chemotherapeutic drugs. The current study has assessed genetic variants of ABCB1, ABCC1, ABCC2, and ABCG2 genes in 407 lung cancer patients undergoing platinum-based doublet chemotherapy. The association of ABCB1 (C¹²³⁶ T, C³⁴³⁵ T, and G²⁶⁷⁷ T/A), ABCC1 (G³¹⁷³ A and G²¹⁶⁸ A),ABCC2 (G⁴⁵⁴⁴ A), and ABCG2 (C⁴²¹ A) polymorphisms with chemotherapy-induced adverse events were assessed, and statistical analysis was conducted. Our data showed that patients harboring heterozygous (GA) genotype for ABCC1 G³¹⁷³ A had an increased risk of developing leukopenia (odds ratio [OR] = 1.88, p = 0.04) and anemia (adjusted odds ratio [AOR] = 2.70, p = 0.03). For ABCC2 G⁴⁵⁴⁴ A polymorphism, patients harboring one copy of the mutant (GA) allele showed an increased risk of developing anemia (OR = 4.24, p = 0.03). After adjusting with various confounding factors, the heterozygous (GA) genotype showed a 5.63-fold increased risk of developing anemia (AOR = 5.63, p = 0.03). The ABCB1 G²⁶⁷⁷ A (OR = 0.37, p = 0.008) and ABCC1 G³¹⁷³ A (OR = 0.54, p = 0.04) polymorphism showed a lower incidence of developing nephrotoxicity. In ABCG2 C⁴²¹ A polymorphism, patients harboring heterozygous (CA) genotype had a lower incidence of having diarrhea (OR = 0.25, p = 0.04). An increased risk of having diarrhea was observed in the heterozygous genotype (GA) for ABCC1 G³¹⁷³ A polymorphism (AOR = 2.78, p = 0.04). An increased risk of liver injury was found in the patients carrying heterozygous genotype of the ABCC1 G³¹⁷³ A (OR = 2.06, p = 0.02) and ABCB1 C¹²³⁶ T (OR = 1.85, p = 0.01). This study demonstrates the role of polymorphic variations in ABCB1, ABCC1, ABCC2, and ABCG2 in predicting hematological, nephrotoxicity, gastrointestinal, and hepatotoxicity.

Impact of ABCB1, ABCC1, ABCC2, and ABCG2 variants in predicting prognosis and clinical outcomes of north Indian lung cancer patients undergoing platinum-based doublet chemotherapy

BACKGROUND

ABC transporters are membrane proteins expressed in the lungs and are crucial for efflux of various chemotherapeutic agents. Polymorphisms of ABC transporters have a certain impact on the transporter activity because their expression levels may influence the extent and longevity of chemotherapeutic drug outflow, affecting patient outcomes. The present study aimed to assess the impact of ABCB1, ABCC1/2, and ABCG2 gene variants in predicting prognosis and clinical outcomes in lung carcinoma patients.

METHODS

In total, 502 lung cancer patients undergoing platinum-based chemotherapy were recruited in this prospective study. Genotyping of ABCB1 (C¹²³⁶ T, C³⁴³⁵ T, and G²⁶⁷⁷ T/A), ABCC1 (G³¹⁷³ A and G²¹⁶⁸ A), ABCC2 (G⁴⁵⁴⁴ A), and ABCG2 (C⁴²¹ A) polymorphisms in Northern Indian lung carcinoma patients were evaluated using polymerase chain reaction-restriction fragment length polymorphism analysis.

RESULTS

Poor survival outcomes were noted in patients carrying a heterozygous genotype (CT) for the ABCB1 C¹²³⁶ T polymorphism compared to the wild-type genotype (CC) (p = 0.04). The mutant genotype (AA) for ABCC1 G³¹⁷³ A exhibited a lower median survival time compared to the reference genotype (GG) (p = 0.009). Lower survival was observed in individuals carrying a heterozygous genotype (GA) for ABCC2 G⁴⁵⁴⁴ A polymorphism compared to the wild-type genotype (GG) (p = 0.017). Small cell lung cancer patients with the ABCB1 G²⁶⁷⁷ A polymorphism having a heterozygous genotype (GA) showed poor survival compared to the wild-type genotype (GG) (p = 0.03). For ABCC1 G³¹⁷³ A, adenocarcinoma patients having a mutant genotype (AA) had reduced survival compared to the wild-type (GG) genotype (p = 0.03). For ABCB1 C³⁴³⁵ T, individuals carrying a heterozygous (CT) (p = 0.018) and mutant (TT) genotype (p = 0.007) had poor survival compared to the wild-type (CC) genotype in patients treated with pemetrexed and cisplatin. The patients administered cisplatin and irinotecan and having mutant alleles (AA) for the ABCB1 G²⁶⁷⁷ A polymorphism showed a lower survival compared to the individuals carrying wild-type alleles (GG) (p = 0.009).

CONCLUSIONS

Our findings suggest that ABCB1 C¹²³⁶ T, ABCB1 C³⁴³⁵ T, ABCB1 G²⁶⁷⁷ A, ABCC1 G³¹⁷³ A, and ABCC2 G⁴⁵⁴⁴ A are involved in predicting prognosis. Genotyping of the ABC polymorphism is essential for predicting prognosis in lung carcinoma patients.

Impact of Genetic Polymorphisms on Phenytoin Pharmacokinetics and Clinical Outcomes in the Middle East and North Africa Region

BACKGROUND

Genetic polymorphisms are known to influence outcomes with phenytoin yet effects in the Middle East and North Africa region are poorly understood.

OBJECTIVES

The objective of this systematic review was to evaluate the impact of genetic polymorphisms on phenytoin pharmacokinetics and clinical outcomes in populations originating from the Middle East and North Africa region, and to characterize genotypic and allelic frequencies within the region for genetic polymorphisms assessed.

METHODS

MEDLINE (1946-3 May, 2017), EMBASE (1974-3 May, 2017), Pharmacogenomics Knowledge Base, and Public Health Genomics Knowledge Base online databases were searched. Studies were included if genotyping and analyses of phenytoin pharmacokinetics were performed in patients of the Middle East and North Africa region. Study quality was assessed using a National Institutes of Health assessment tool. A secondary search identified studies reporting genotypic and allelic frequencies of assessed genetic polymorphisms within the Middle East and North Africa region.

RESULTS

Five studies met the inclusion criteria. CYP2C9, CYP2C19, and multidrug resistance protein 1 C3435T variants were evaluated. While CYP2C9*2 and *3 variants significantly reduced phenytoin metabolism, the impacts of CYP2C19*2 and *3 variants were unclear. The multidrug resistance protein 1 CC genotype was associated with drug-resistant epilepsy, but reported impacts on phenytoin pharmacokinetics were conflicting. Appreciable variability in minor allele frequencies existed both between and within countries of the Middle East and North Africa region.

CONCLUSIONS

CYP2C9 decrease-of-function alleles altered phenytoin pharmacokinetics in patients originating from the Middle East and North Africa region. The impacts of CYP2C19 and multidrug resistance protein 1 C3435T variants on phenytoin pharmacokinetic and clinical outcomes are unclear and require further investigation. Future research should focus on the clinical outcomes associated with phenytoin therapy. PROSPERO 2017: CRD42017057850.