Pharmacogenetics of taxane-induced neurotoxicity in breast cancer: Systematic review and meta-analysis.

Taxane-based chemotherapy regimens are used as first-line treatment for breast cancer. Neurotoxicity, mainly taxane-induced peripheral neuropathy (TIPN), remains the most important dose-limiting adverse event. Multiple genes may be associated with TIPN; however, the strength and direction of the association remain unclear. For this reason, we systematically reviewed observational studies of TIPN pharmacogenetic markers in breast cancer treatment. We conducted a systematic search of terms alluding to breast cancer, genetic markers, taxanes, and neurotoxicity in Ovid, ProQuest, PubMed, Scopus, Virtual Health, and Web of Science. We assessed the quality of evidence and bias profile. We extracted relevant variables and effect measures. Whenever possible, we performed random-effects gene meta-analyses and examined interstudy heterogeneity with meta-regression models and subgroup analyses. This study follows the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and STrengthening the REporting of Genetic Association Studies (STREGA) reporting guidance. A total of 42 studies with 19,431 participants were included. These evaluated 262 single-nucleotide polymorphisms (SNPs) across 121 genes. We conducted meta-analyses on 23 genes with 60 SNPs (19 studies and 6246 participants). Thirteen individual SNPs (ABCB1-rs2032582, ABCB1-rs3213619, BCL6/-rs1903216, /CAND1-rs17781082, CYP1B1-rs1056836, CYP2C8-rs10509681, CYP2C8-rs11572080, EPHA5-rs7349683, EPHA6-rs301927, FZD3-rs7001034, GSTP1-rs1138272, TUBB2A-rs9501929, and XKR4-rs4737264) and the overall SNPs' effect in four genes (CYP3A4, EphA5, GSTP1, and SLCO1B1) were statistically significantly associated with TIPN through meta-analysis. In conclusion, through systematic review and meta-analysis, we found that polymorphisms, and particularly 13 SNPs, are associated with TIPN, suggesting that genetics does play a role in interindividual predisposition. Further studies could potentially use these findings to develop individual risk profiles and guide decision making.

Lack of Delta-Sarcoglycan (Sgcd) Results in Retinal Degeneration.

Age-related macular degeneration (AMD) is the leading cause of central vision loss and severe blindness among the elderly population. Recently, we reported on the association of the SGCD gene (encoding for δ-sarcoglycan) polymorphisms with AMD. However, the functional consequence of Sgcd alterations in retinal degeneration is not known. Herein, we characterized changes in the retina of the Sgcd knocked-out mouse (KO, Sgcd-/-). At baseline, we analyzed the retina structure of three-month-old wild-type (WT, Sgcd+/+) and Sgcd-/- mice by hematoxylin and eosin (H&E) staining, assessed the Sgcd-protein complex (α-, ß-, γ-, and ε-sarcoglycan, and sarcospan) by immunofluorescence (IF) and Western blot (WB), and performed electroretinography. Compared to the WT, Sgcd-/- mice are five times more likely to have retinal ruptures. Additionally, all the retinal layers are significantly thinner, more so in the inner plexiform layer (IPL). In addition, the number of nuclei in the KO versus the WT is ever so slightly increased. WT mice express Sgcd-protein partners in specific retinal layers, and as expected, KO mice have decreased or no protein expression, with a significant increase in the α subunit. At three months of age, there were no significant differences in the scotopic electroretinographic responses, regarding both a- and b-waves. According to our data, Sgcd-/- has a phenotype that is compatible with retinal degeneration.

Effects of (-)-epicatechin on frontal cortex DAPC and dysbindin of the mdx mice.

INTRODUCTION: Multiple components of the dystrophin-associated protein complex (DAPC) are expressed in numerous tissues including the brain. Members of the DAPC and dysbindin are abnormally expressed in the brain of Duchenne Muscular Dystrophy (DMD) patients, which has been associated with cognitive impairments. However, little is known about the expression pattern of individual members of the DAPC in animal models of DMD and their relationship with dysbindin. METHODS: Ten mdx mice were randomly allocated into a control and intervention group [(-)-epicatechin (Epi) 1mg/kg/day for four weeks] and results compared to a wild-type mice. After sacrifice, brain pre-frontal cortices were collected for Western blotting and immunoprecipitation assays, and sagittal sections processed for immunohistochemistry. RESULTS: Epi promotes a partial recovery of DAPC members [α1-Syntrophin, sarcoglycans (SG), dystrophin 71 (Dp71)], dysbindin, and utrophin protein levels. Epi also appears to restore the association of DAPC between dysbindin, and utrophin with Dp71 and ε-SG. Co-immunostaining evidence increased protein levels of dysbindin, dystrophin, and ε-SG and their colocalization. CONCLUSIONS: Altogether, results suggest that Epi is capable of restoring pre-frontal cortex DAPC and dysbindin levels of mdx mice towards that of healthy brains. The functional implications of such studies warrant further investigation.

Pharmacogenetics of response to neoadjuvant paclitaxel treatment for locally advanced breast cancer.

Locally advanced breast cancer (LABC) cases have a varying five-year survival rate, mainly influenced by the tumor response to chemotherapy. Paclitaxel activity (response rate) varies across populations from 21.5% to 84%. There are some reports on genetic traits and paclitaxel; however, there is still considerable residual unexplained variability. In this study, we aimed to test the association between eleven novel markers and tumor response to paclitaxel and to explore if any of them influenced tumor protein expression. We studied a cohort of 140 women with LABC. At baseline, we collected a blood sample (for genotyping), fine needle aspirates (for Western blot), and tumor measurements by imaging. After follow-up, we ascertained the response to paclitaxel monotherapy by comparing the percent change in the pre-, post- tumor measurements after treatment. To allocate exposure, we genotyped eleven SNPs with TaqMan probes on RT-PCR and regressed them to tumor response using linear modeling. In addition, we compared protein expression, between breast tumors and healthy controls, of those genes whose genetic markers were significantly associated with tumor response. After adjusting for multiple clinical covariates, SNPs on the LPHN2, ROBO1, SNTG1, and GRIK1 genes were significant independent predictors of poor tumor response (tumor growth) despite paclitaxel treatment. Moreover, proteins encoded by those genes are significantly downregulated in breast tumor samples.

[Improvements in the diagnosis of dystrophinopathies: what have we learnt in these last 20 years?]. / Mejoras en el diagnostico de distrofinopatias: que hemos aprendido despues de 20 anos?

INTRODUCTION. Dystrophinopathies are X-linked genetic disorders caused by mutations in the DMD gene. Genetic tests are of utmost importance for management and genetic counseling of these diseases. However, the complexity of the DMD gene is a challenge for diagnosis. AIM. To describe recent advances in the diagnosis of dystrophinopathies, after 20 years since the firsts molecular assays for genetic screening for these diseases. DEVELOPMENT. Currently, a variety of strategies such as automated mutation detection, cell-based methods and high throughput haplotyping have been developed to facilitate diagnosis of dystrophinopathies, carrier detection, prenatal and preimplantation diagnosis. CONCLUSION. New technologies have improved early detection and optimal management of dystrophinopathies and have established the basis for future molecular medicine. The most significant advances in dystrophinopathy diagnosis are reviewed herein.

Mejoras en el diagnóstico de distrofinopatías: ¿qué hemos aprendido después de 20 años? / Improvements in the diagnosis of dystrophinopathies: what have we learnt in these last 20 years?

Introducción. Las distrofinopatías son trastornos genéticos ligados al cromosoma X causados por mutaciones en el gen DMD. Las pruebas genéticas son de suma importancia para la gestión y el asesoramiento genético de estas enfermedades. Sin embargo, la complejidad del gen DMD es un desafío para el diagnóstico. Objetivo. Describir los avances recientes en el diagnóstico de distrofinopatías, después de 20 años de los primeros ensayos moleculares para la detección genética de estas enfermedades. Desarrollo. En la actualidad, se han desarrollado una variedad de estrategias, como la detección de mutaciones automatizada, los métodos basados en células y la haplotipificación de alto rendimiento, para facilitar el diagnóstico de distrofinopatías, la detección de portadoras, el diagnóstico prenatal y preimplantacional. Conclusión. Las nuevas tecnologías han mejorado la detección temprana y el manejo óptimo de distrofinopatías, y han establecido la base para la medicina molecular en el futuro. Los avances más importantes en el diagnóstico de distrofinopatías se revisan en este documento (AU)

Introduction. Dystrophinopathies are X-linked genetic disorders caused by mutations in the DMD gene. Genetic tests are of utmost importance for management and genetic counseling of these diseases. However, the complexity of the DMD gene is a challenge for diagnosis. Aim. To describe recent advances in the diagnosis of dystrophinopathies, after 20 years since the firsts molecular assays for genetic screening for these diseases. Development. Currently, a variety of strategies such as automated mutation detection, cell-based methods and high throughput haplotyping have been developed to facilitate diagnosis of dystrophinopathies, carrier detection, prenatal and preimplantation diagnosis. Conclusion. New technologies have improved early detection and optimal management of dystrophinopathies and have established the basis for future molecular medicine. The most significant advances in dystrophinopathy diagnosis are reviewed herein. (AU)