The Gly16 Allele of the Gly16Arg Single-Nucleotide Polymorphism in the β₂-Adrenergic Receptor Gene Augments Perioperative Use of Vasopressors: A Retrospective Cohort Study

Genetic polymorphisms are associated with individual susceptibility to dexmedetomidine

Introduction: Dexmedetomidine (DXM) is widely used as an adjuvant to anesthesia or a sedative medicine, and differences in individual sensitivity to the drug exist. This study aimed to investigate the effect of genetic polymorphisms on these differences. Methods: A total of 112 patients undergoing hand surgery were recruited. DXM 0.5 μg/kg was administered within 10 min and then continuously injected (0.4 μg/kg/h). Narcotrend index, effective dose and onset time of sedation, MAP, and HR were measured. Forty-five single nucleotide polymorphisms (SNPs) were selected for genotype. Results: We observed individual differences in the sedation and hemodynamics induced by DXM. ABCG2 rs2231142, CYP2D6 rs16947, WBP2NL rs5758550, KATP rs141294036, KCNMB1 rs11739136, KCNMA1 rs16934182, ABCC9 rs11046209, ADRA2A rs1800544, and ADRB2 rs1042713 were shown to cause statistically significant (p < 0.05) influence on the individual variation of DXM on sedation and hemodynamics. Moreover, the multiple linear regression analysis indicated sex, BMI, and ADRA2A rs1800544 are statistically related to the effective dose of DXM sedation. Discussion: The evidence suggests that the nine SNPs involved in transport proteins, metabolic enzymes, and target proteins of DXM could explain the individual variability in the sedative and hemodynamic effects of DXM. Therefore, with SNP genotyping, these results could guide personalized medication and promote clinical and surgical management.

Study of the Association of Single Nucleotide Polymorphisms in Candidate Genes With Sevoflurane

The susceptibility of different individuals to anesthetics varies widely, and sevoflurane is no exception. We hypothesized that polymorphisms in genes involved in pharmacokinetics and pharmacodynamics may explain this variation. A total of 151 individuals undergoing otorhinolaryngology surgery were included. The influence of genetic polymorphisms on sevoflurane sensitivity were investigated through SNaPshot technology. Individuals carrying KCNK2 rs6686529 G > C, MTRR rs3733784 TT, rs2307116 GG, or rs1801394 AA polymorphisms had a higher sensitivity to the sedative effect of sevoflurane than those without those polymorphisms. The univariate linear regression analysis indicated that MTRR rs3733784 TT, rs2307116 GG, and rs1801394 AA were potentially significant predictors of higher sensitivity to the sedative effect of sevoflurane. Moreover, CYP2E1 rs3813867 G > C and rs2031920 C > T, GABRG1 rs279858 T > C, KCNK3 rs1275988 CC, GRIN2B rs1806201 GG, MTRR rs2307116 G > A, and rs1801394 A > G were associated with a higher sensitivity to the cardiovascular effect of sevoflurane. Our results suggested that 9 single nucleotide polymorphisms in genes involved in metabolizing enzymes, transport proteins, target proteins of sevoflurane and folate metabolism may help to explain individual differences in the susceptibility to the sedative or cardiovascular effect of sevoflurane.

Influence of ADRB1, ADRB2, and COMT Genetic Polymorphisms on Postoperative Outcomes of Patients Undergoing Cardiac Valve Surgery

PURPOSE

The aim of this study is to prospectively investigate the influence of ADRB and COMT gene polymorphisms on postoperative outcomes of patients undergoing cardiac surgery.

METHODS

This prospective cohort study included 223 patients undergoing elective cardiac valve surgery using cardiopulmonary bypass. Demographic information, intraoperative data, postoperative data, and blood samples were collected. Patients were genotyped for single-nucleotide polymorphisms (SNPs) of ADRB1 rs1801253, ADRB2 rs1042713, and COMT rs4680. Major adverse cardiovascular and cerebrovascular events (MACCEs) were used as the primary outcome to evaluate the postoperative prognosis of patients. Secondary outcomes included the duration of mechanical ventilatory support, intensive care unit stay, postoperative hospital stay, and postoperative need of inotropic or vasoactive agents.

FINDINGS

The overall incidence of MACCEs was 15.2%. Among 3 SNP loci, only different genotyped carriers of ADRB2 rs1042713 had statistically significant differences in the incidence of MACCEs (P = 0.005), especially for acute kidney injury (P = 0.023). The proportions of postoperative norepinephrine demand of patients carrying the AA genotype of ADRB2 rs1042713 (P = 0.016) and the AG genotype of COMT rs4680 (P = 0.018) were low. The duration of mechanical ventilatory support (P = 0.034) and postoperative hospital stay (P = 0.045) of patients carrying the AG genotype of COMT rs4680 was shortest. After multiple logistic regression analysis, we found that the G allele carriers of ADRB2 rs1042713 had a higher risk of MACCEs (AG vs AA genotype: odds ratio [OR] = 4.348; 95% CI, 1.529-12.359, P = 0.006; GG vs AA genotype: OR = 3.722; 95% CI, 1.060-13.071; P = 0.040), in particular with acute kidney injury (AG vs AA genotype: OR = 5.273; 95% CI, 1.093-25.451; P = 0.038; GG vs AA genotype: OR = 7.533; 95% CI, 1.275-44.522; P = 0.026). There was no SNP-SNP interaction found among the 3 SNPs with multifactor dimensionality reduction analysis.

IMPLICATION

The ADRB2 rs1042713 polymorphism might be related to prognosis of patients undergoing cardiac surgery. Patients carrying the G allele of ADRB2 rs1042713 had a higher risk of developing MACCEs, especially acute kidney injury. chictr.org.com identifier: ChiCTR1800015105.

β2 adrenergic interaction and cardiac autonomic function: effects of aerobic training in overweight/obese individuals

PURPOSE

To verify the influence of different volumes and intensities of aerobic exercise on cardiac autonomic function (CAF) through heart rate variability (HRV) analysis as well the influence of β2 adrenergic receptor (ADRB2) variants in overweight/obese individuals.

METHODS

70 physically inactive adults were randomly allocated into the following 16-week training: 1-high-intensity interval training (HIIT) (n = 25, 1 × 4 min bout at 85-95%HR peak, 3×/week), 4-HIIT (n = 26, 4 × 4 min bouts at 85-95%HR peak, interspersed with 3 min of recovery at 50-70%HR peak, 3×/week), and moderate continuous training (MCT) (n = 19, 30 min at 60-70%HR peak, 5×/week). Before and after the exercise training, anthropometric, BP, cardiorespiratory fitness, and HRV measures were evaluated. R-R intervals recorded for 10 min in a supine position at pre- and post-intervention were used to analyze HRV in the plot-Poincare indexes (SD1, SD2), and frequency-domain (LF, HF, LF/HF). Full blood samples were used for genotyping.

RESULTS

4-HIIT and MCT showed positive outcomes for almost all variables while 1-HIIT had a positive influence only on SBP and SD2 index. No associations were observed between isolated ADRB2 variants and changes in HRV. In the analysis of the interaction genotypes, all groups responded positively for the SD1 index of HRV and only the H1 (GG and CC) and H2 (GG and CG + GG) groups presented increases in the RMSSD index. Furthermore, there was an increase in the LF index only in the H3 (CC and AA + AG) and H4 (AA + AG and CG + GG) groups.

CONCLUSIONS

ADRB2 variants and aerobic exercise training are important interacting variables to improve autonomic function and other health variables outcomes in overweight or obese individuals.

Challenges in anesthesia personalization: resolving the pharmacogenomic puzzle

Clinicians are witnessing differences in the doses required for induction and maintenance of anesthesia, as well as prolonged recovery in some patients. Predictable factors like patient characteristics, factors related to the procedure, pharmacological characteristics of anesthetics and adjunctive drugs, might explain some of the observed differences. However, the role of various polymorphisms of genes encoding for drugs’ molecular targets, transporters and metabolic enzymes can have a significant impact on anesthesia outcome, too. In the present paper, we critically discuss pharmacological characteristics of the most common drugs used in anesthesia, with a focus on the possible genetic background of unpredictable diversities in anesthesia outcomes.

Dissecting genetic factors affecting phenylephrine infusion rates during anesthesia: a genome-wide association study employing EHR data

BACKGROUND

The alpha-adrenergic agonist phenylephrine is often used to treat hypotension during anesthesia. In clinical situations, low blood pressure may require prompt intervention by intravenous bolus or infusion. Differences in responsiveness to phenylephrine treatment are commonly observed in clinical practice. Candidate gene studies indicate genetic variants may contribute to this variable response.

METHODS

Pharmacological and physiological data were retrospectively extracted from routine clinical anesthetic records. Response to phenylephrine boluses could not be reliably assessed, so infusion rates were used for analysis. Unsupervised k-means clustering was conducted on clean data containing 4130 patients based on phenylephrine infusion rate and blood pressure parameters, to identify potential phenotypic subtypes. Genome-wide association studies (GWAS) were performed against average infusion rates in two cohorts: phase I (n = 1205) and phase II (n = 329). Top genetic variants identified from the meta-analysis were further examined to see if they could differentiate subgroups identified by k-means clustering.

RESULTS

Three subgroups of patients with different response to phenylephrine were clustered and characterized: resistant (high infusion rate yet low mean systolic blood pressure (SBP)), intermediate (low infusion rate and low SBP), and sensitive (low infusion rate with high SBP). Differences among clusters were tabulated to assess for possible confounding influences. Comorbidity hierarchical clustering showed the resistant group had a higher prevalence of confounding factors than the intermediate and sensitive groups although overall prevalence is below 6%. Three loci with P < 1 × 10^-6 were associated with phenylephrine infusion rate. Only rs11572377 with P = 6.09 × 10^-7, a 3'UTR variant of EDN2, encoding a secretory vasoconstricting peptide, could significantly differentiate resistant from sensitive groups (P = 0.015 and 0.018 for phase I and phase II) or resistant from pooled sensitive and intermediate groups (P = 0.047 and 0.018).

CONCLUSIONS

Retrospective analysis of electronic anesthetic records data coupled with the genetic data identified genetic variants contributing to variable sensitivity to phenylephrine infusion during anesthesia. Although the identified top gene, EDN2, has robust biological relevance to vasoconstriction by binding to endothelin type A (ET_A) receptors on arterial smooth muscle cells, further functional as well as replication studies are necessary to confirm this association.

Polymorphisms associated with fentanyl pharmacokinetics, pharmacodynamics and adverse effects

Fentanyl is an agonist of the μ-opioid receptor commonly used in the treatment of moderate-severe pain. In order to study whether pharmacogenetics explains some of the variability in the response to fentanyl, several genes related to fentanyl receptors, transporters and metabolic enzymes have been analysed. Thirty-five healthy volunteers (19 men and 16 women) receiving a single 300 μg oral dose of fentanyl were genotyped for 9 polymorphisms in cytochrome P450 (CYP) enzymes (CYP3A4 and CYP3A5), ATP-binding cassette subfamily B member 1 (ABCB1), opioid receptor mu 1 (OPRM1), catechol-O-methyltransferase (COMT) and adrenoceptor beta 2 (ADRB2) by real-time PCR. Fentanyl concentrations were measured by ultra-performance liquid chromatography combined with tandem mass spectrometry (UPLC-MS/MS). Fentanyl pharmacokinetics is affected by sex. Carriers of the CYP3A4*22 allele, which is known to reduce the mRNA expression, showed higher area under the concentration-time curve (AUC) and lower clearance (Cl) values. Although this finding might be of importance, its validity needs to be confirmed in other similar settings. Furthermore, carriers of the ABCB1 C1236T T/T genotype presented a lower AUC and higher Cl, as well as lower half-life (T_1/2 ). As volunteers were blocked with naltrexone, the effect of fentanyl on pharmacodynamics might be biased; however, we could observe that fentanyl had a hypotensive effect. Moreover, ADRB2 C523A A allele carriers showed a tendency towards reducing systolic blood pressure. Likewise, OPRM1 and COMT minor allele variants were risk factors for the development of somnolence. CYP3A5*3, ABCB1 C3435T and ABCB1 G2677T/A were not associated with fentanyl's pharmacokinetics, pharmacodynamics and safety profile.

ADRB2 gly16gly Genotype, Cardiac Output, and Cerebral Oxygenation in Patients Undergoing Anesthesia for Abdominal Aortic Aneurysm Surgery

BACKGROUND

Gly16arg polymorphism of the adrenergic β2-receptor is associated with the elevated cardiac output (Q) in healthy gly16-homozygotic subjects. We questioned whether this polymorphism also affects Q and regional cerebral oxygen saturation (SCO2) during anesthesia in vascular surgical patients.

METHODS

One hundred sixty-eight patients (age 71 ± 6 years) admitted for elective surgery were included. Cardiovascular variables were determined before and during anesthesia by intravascular pulse contour analysis (Nexfin) and SCO2 by cerebral oximetry (INVOS 5100C). Genotyping was performed with the TaqMan assay.

RESULTS

Before anesthesia, Q and SCO2 were 4.7 ± 1.2 L/min and 66% ± 8%, respectively, and linearly correlated (r = 0.35, P < .0001). In patients with the gly16gly genotype baseline, Q was approximately 0.4 L/min greater than in arg16 carriers (CI95: 0.0-0.8, Pt test = .03), but during anesthesia, the difference was 0.3 L/min (Pmixed-model = .07). Post hoc analysis revealed the change in SCO2 from baseline to the induction of anesthesia to be on average 2% greater in gly16gly homozygotes than in arg16 patients when adjusted for the change in Q (P = .03; CI95: 0.2-4.0%).

CONCLUSIONS

This study suggests that the β2-adrenoceptor gly16gly genotype is associated with the elevated resting Q. An interesting trend to greater frontal lobe oxygenation at induction of anesthesia in patients with gly16gly genotype was found, but because of insufficient sample size and lack of PCO2 control throughout the measurements, the presented data may only serve as the hypothesis generating for future studies. The confidence limits indicate that the magnitude of the effects may range from clinically insignificant to potentially important.