Multiplex genotyping of CYP3A4, CYP3A5, CYP2C9 and CYP2C19 SNPs using MALDI-TOF mass spectrometry.

BACKGROUND: Pharmacogenetics is the study of genetic variations that cause alterations in drug level, drug response and adverse drug reactions. SNPs found in CYP450 genes have the greatest genetic influences on interindividual variability in drug bioavailability. The polymorphic nature of these genes may modulate several enzyme levels that affect individual responses to pharmacological treatment. Among them, CYP3A4, CYP3A5, CYP2C9 and CYP2C19 isoforms of CYP450 enzymes are involved in the metabolism of many commonly prescribed drugs. AIMS: In this study, we would like to develop a CYP450 genotyping platform that could lead a complete definition of a patient's metabolic genotype in order to improve the clinical outcome of some drug treatments. MATERIALS & METHODS: We used matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) (Sequenom) to develop a SNP genotyping method. RESULTS: This MALDI-TOF-based multiplexing system allows the simultaneous and efficient genotyping of a set of CYP450 gene polymorphisms. CONCLUSION: The multiple CYP450 gene testing achieved with this application can be used to develop diagnostic tests to predict drug responses and clinical outcomes.

EDA2R is associated with androgenetic alopecia.

Androgenetic alopecia (AGA) is a common heritable polygenic disorder whose genetics is not fully understood, even though it seems to be X-linked. We carried out an epidemiological survey for AGA on 9,000 people from 8 isolated villages of a secluded region of Sardinia (Ogliastra), and identified a large cohort of affected individuals. We genotyped 200 cases and 200 controls (mean kinship 0.001) with the 500k chip array and conducted case-control association analysis on the X chromosome. We identified Xq11-q12 as strongly associated with AGA. In particular, we found that rs1352015 located 8 kb from the EDA2R gene showed the best result (P=7.77e(-7)). This region also contains the AR gene, hence we tested both genes in 492 cases and 492 controls. We found that the non-synonymous SNP rs1385699 on EDA2R gave the best result (P=3.9e(-19)) whereas rs6152 on the AR gene is less significant (P=4.17e(-12)). Further statistical analysis carried out by conditioning each gene to the presence of the other showed that the association with EDA2R is independent while the association with AR seems to be the result of linkage disequilibrium. These results give insight into the pathways involved in AGA etiology.

Social isolation increases the response of peripheral benzodiazepine receptors in the rat.

Social isolation of rats for 30 days immediately after weaning reduces the cerebrocortical and plasma concentrations of progesterone, 3alpha-hydroxy-5alpha-pregnan-20-one (3alpha,5alpha-TH PROG), and 3alpha,5alpha-tetrahydrodeoxycorticosterone (3alpha,5alpha-TH DOC). The percentage increases in the brain and plasma concentrations of these neuroactive steroids apparent 30 min after intraperitoneal injection of the peripheral benzodiazepine receptor (PBR) ligand CB 34 (25 mg/kg) have now been shown to be markedly greater in isolated rats than in group-housed controls. The CB 34-induced increase in the abundance of 3alpha,5alpha-TH PROG was more pronounced in the brain than in the plasma of isolated rats. Analysis of [3H]PK 11195 binding to membranes prepared from the cerebral cortex, adrenals, or testis revealed no significant difference in either the maximal number of binding sites for this PBR ligand or its dissociation constant between isolated and group-housed animals. Social isolation also induced a small but significant decrease in the plasma concentration of adrenocorticotropic hormone. Moreover, CB 34 increased the plasma concentration of this hormone to a greater extent in isolated rats than in group-housed animals. The persistent decrease in the concentrations of neuroactive steroids induced by social isolation might thus be due to an adaptive decrease in the activity either of the hypothalamic-pituitary-adrenal axis or of PBRs during the prolonged stress, reflecting a defense mechanism to limit glucocorticoid production. The larger increase in neuroactive steroid concentrations induced by CB 34 and the enhanced pituitary response to this compound in isolated rats indicate that this mild stressor increases the response of PBRs.