الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
”The CYP450 enzymes, which include CYP2D6, CYP3A4, and CYP3A5, are one of the most important phase I drug enzymes that contribute to the metabolization of a broad range of therapeutic medicines, including HCQ. Through its immunomodulatory and anti-inflammatory properties, HCQ helps in the prevention of flares and better survival in SLE disease. The wide range of HCQ among individuals implies that drug concentration and efficacy may be related. Herein, we established a relationship between blood HCQ concentration and lupus activity, and analyzed determinant of blood HCQ concentrations in SLE patients as human P450 enzymes such as CYP2D6, -3A4, and -3A5. Besides, the frequency of common allelic variants of CYP2D6 including CYP2D6*2, *4, *5, *10, *41 and the presence of gene duplications, as well as CYP3A4*22 and CYP3A5*3 were assessed in a healthy cohort to further our understanding of these important pharmacogenes variation in the Egyptian population which laying down the groundwork for future research to avoid dose-related adverse effects or therapeutic failure for drugs that are metabolized by such pharmacogenes. Subjects and methods: This study consisted of 75 patients with systemic lupus and all of whom are on HCQ and another cohort of 145 unrelated healthy participants. Study participants were recruited at Mansoura University Children’s Hospital. Patients received 200 mg of HCQ tablets at a daily dose of 6.5 milligrams per kilogram of body weight. For clinical assessment of SLE patients, A SELENA-SLEDAI criterion was used and laboratory tests including C3, C4, Cr, Ca, phosphorous, ANA and anti-DNA were performed. DNA samples from SLE patients and healthy volunteers were genotyped for the following SNPs using commercially available TaqMan assays: rs35599367, rs776746, rs16947, rs3892097, rs1065852 and rs28371725 and used to call the following alleles: CYP3A4*22, CYP3A5*3 and CYP2D6*2, *4, *10 and *41. To further our understanding of CYP2D6 variation in the 145 healthy participants, TaqMan copy number assay, targeting exon 9 of CYP2D6 was utilized to determine the presence of CNVs. Furthermore, an HPLC method was conducted for the quantification of HCQ, DCQ and DHCQ in the whole blood of SLE patients. Results: The majority of patients were females [N=63 (84%)]. Fever, oral ulcers, and arthritis were among the most common symptoms that occurred at a percentage of 20-40%. Systemic lupus erythromatuses (SLE) patients with proteinuria had 27.9 times higher odds to exhibit moderate or severe disease activity, compared to RBC count (OR = 0.2) that was found to be protective against the risk of having moderate or severe disease activity. Unlike the HCQ:DCQ and HCQ:DHCQ ratios, there was a statistically significant negative correlation of moderate strength between SLE disease activity and blood levels of HCQ, DCQ and DHCQ. There was a statistically significant negative correlation of moderate strength between lupus nephritis grades (renal biopsy) and only the blood levels of DCQ. Regarding CYP2D6 genotypes association with HCQ drug level, as well as its metabolites and their ratios, levels of HCQ, DCQ, and DHCQ in the (CYP2D*1/*4, *2/*4) group were statistically significantly lower than the (CYP2D*1/*1, *1/*2, *2/*2) group, as well as the (CYP2D6*1/*10, *2/*10) group while the CYP3A5*3/*3 genotype had a statistically significantly higher concentrations than the CYP3A5*1/*3 genotype. Besides, there was no statistical significance between the combined CYP3A4/5 phenotype (IM and NM) and the HCQ drug level or its metabolites, or their ratios. Regarding the healthy cohort, all interrogated allelic variants were identified in this population samples. Allele frequencies differed from those found in other populations. Among the 145 study subjects, normal metabolizer was the most commonly observed phenotype for CYP2D6 followed by intermediate metabolizers. No poor metabolizers were identified although allele frequencies suggest that 1–2% have this phenotype. The predominance of the poor expresser CYP3A5*3 allelic variant (86.2%) was comparable to that seen in European populations (94.3%), however, the frequency of this allele differs greatly among populations. In line with other findings, the decreased activity CYP3A4*22 allele was rare, and its frequency was not found to be significantly different when compared with other populations. No significant difference was observed between observed frequencies of SLE patients and the 145 healthy control subjects. Conclusions: This study provides new data for the relationship of CYP2D6, CYP3A4 and CYP3A5 genetic variations and HCQ drug level as well as its metabolites in SLE patients. The present study indicates that HCQ, DCQ and DHCQ are related to CYP3A5 polymorphisms than CYP2D6 and CYP3A4; therefore, it is important to consider the clinical value of an individual’s CYP polymorphisms before prescribing HCQ. Furthermore, the current findings suggest that assessing HCQ blood level can help predict the emergence of disease flares. However, more comprehensive studies with larger number of patients are needed to confirm and strengthen the clinical utility our findings. Regarding the healthy cohort, this preliminary assessment provides insights into the prevalence of well-characterized and functionally relevant pharmacogene allelic variants. This study contributes to a better understanding of variability in drug metabolism and response in Egyptians and paves the way for future research and implementation of precision medicine in this population.