Frequency of CYP2C9 (*2, *3 and IVS8‑109A>T) allelic variants, and their clinical implications, among Mexican patients with diabetes mellitus type 2 undergoing treatment with glibenclamide and metformin

Abstract

The majority of Mexican patients with diabetes mellitus type 2 (DMT2) (67.9-85.0%) are prescribed sulphonylureas (SUs), which are metabolized by cytochrome P450 2C9 (abbreviated as CYP2C9 ). SUs are a type of oral anti-diabetic compound which inhibit ATP-sensitive potassium channels, thus inducing glucose-independent insulin release by the β-pancreatic cells. The wide variability reported in SU responses has been attributed to the polymorphisms of CYP2C9 . The present study aimed to describe CYP2C9 polymorphisms (*2 , *3 and IVS8-109T ) within a sample of Mexican patients with DMT2, while suggesting the potential clinical implications in terms of glibenclamide response variability. From a sample of 248 patients with DMT2 who initially consented to be studied, those ultimately included in the study were treated with glibenclamide (n=11), glibenclamide combined with metformin (n=112) or metformin (n=76), and were subsequently genotyped using a reverse transcription-quantitative polymerase chain reaction (PCR), end-point allelic discrimination and PCR amplifying enzymatic restriction fragment long polymorphism. Clinical data were gathered through medical record revision. The frequencies revealed were as follows: CYP2C9*1 / *1 , 87.5%; *1 / *2 , 6.5%; *1 / *3 , 5.2%; and CYP2C9 , IVS8-109A>T , 16.1%. Glibenclamide significantly reduced the level of pre-prandial glucose (P<0.01) and the percentage of glycated hemoglobin (%HbA1c; P<0.01) for IVS8-109A>T compared with combined glibenclamide and metformin treatment. Concerning the various treatments with respect to the different genotypes, the percentages obtained were as follows: Glibenclamide A / A , HbA1c<6.5=33.3%; glibenclamide + metformin A / A , HbA1c<6.5=24.6%; glibenclamide A / T , HbA1c<6.5=33.3%; glibenclamide + metformin A / T , HbA1c<6.5=25%; glibenclamide T / T , HbA1c<6.5=100%; and glibenclamide + metformin T / T , HbA1c<6.5=12.5%. Altogether, these results revealed that, although genetically customized prescriptions remain a desirable goal to increase the chances of therapeutic success, within the studied population neither allelic variants nor dosages demonstrated a clear association with biomarker levels. A key limitation of the present study was the lack of ability to quantify either the plasma concentrations of SU or their metabolites; therefore, further, precise experimental and observational studies are required.

Pharmacogenetics of Metformin Transporters Suggests No Association with Therapeutic Inefficacy among Diabetes Type 2 Mexican Patients

“…Reactions were performed in a final reaction volume of 10 μL, with 30 ng genomic DNA template, 1X TaqMan ® Universal PCR Master mix system from Applied Biosystems, 1X each probe assessed ( CYP2C9*1 : C_160889442_10, CYP2C9*2 : rs1799853, C_25625805_10; CYP2C9*3 : rs1057910, C_27104892_10; CYP2C9*6: rs9332131, C_32287221_20; SLC22A1: rs12208357, C__30634096_10; SLC22A1: rs2282143, C__15877554_40; SLC22A1: rs594709, C___1898206_20; SLC22A1: rs622342, C____928527_30; SLC22A1: rs628031, C___8709275_60; SLC22A1: rs683369, C____928536_30; SLC22A1: rs72552763, C__34211613_10; SLC22A2: rs316019, C___3111809_20; SLC22A3: rs2076828, C___2763995_1_; SLC22A3: rs8187725, C__30633894_10; ABCB1: rs1045642, C___7586657_20; ABCB1: rs1128503, C___7586662_10; ABCB1: rs2032582, C_11711720D_40; ABCB1: rs2032582, C_11711720C_30; ABCB1: rs2032588, C__11711718_10), and water. Thermocycling conditions and allelic discrimination to identify the genotypes using allelic discrimination software (Applied Biosystems, Bedford, MA, USA) were previously described [ 16 ]. The intronic polymorphism CYP2C9 IVS8 109A > T (rs1934969) was analyzed using the PCR amplifying enzymatic restriction fragment long polymorphism (PCR/RFLP) method.…”

“…The intronic polymorphism CYP2C9 IVS8 109A > T (rs1934969) was analyzed using the PCR amplifying enzymatic restriction fragment long polymorphism (PCR/RFLP) method. PCR was performed on a Mastercycler ® 384 (Eppendorf, Hamburg, Germany) to identify its presence by following the procedure detailed in Cuautle et al (2019) [ 16 ]. Fragments of 468 and 154 bp cut by HinfI restriction enzyme (New England BioLabs Inc., Ipswitch, MA, USA; cat no.…”

“…We recently described the frequencies and clinical implications of CYP2C9 polymorphisms in DMT2 Mexican-Mestizo patients from Mexico City and we also compared them with reported frequencies from different worldwide analogue populations [ 16 ]. Menjívar et al [ 17 ] also reported the polymorphism frequencies of this gene in Mexico City.…”

“…The wide variability reported in SU responses has been attributed to the polymorphisms of CYP2C9 . The frequency of CYP2C9*1/*2 is 50% lower among patients with DMT2 compared with healthy individuals [ 16 ]. Considering the widely heterogeneous ethnic background of Mexican populations (which comprise > 65 groups) [ 18 ], it is important to further persist in studying the pharmacogenetics of its patients, widening our studies towards OCT1, OCT2, OCT3, and other transporters like ABCB1 that may be involved, as well as polymorphisms of glibenclamide metabolizing enzymes ( CYP2C9 ) in view of its widespread prescription in Mexico.…”

Glycated Hemoglobin is a Biomarker of Renal Failure in Diabetic Patients

“…The mortality rate increases globally by DMT2, 15.15% mortality was observed in Mexico in 2017. High prevalence showed that in 2035 the world suffers from DMT2 at least 15.7 million cases 1 Tanta Faculty of Medicine, Egypt…”