Alexandra Luna-Angulo

IMMUNODETECTION ANALYSIS OF MUSCULAR DYSTROPHIES IN MEXICO

Introduction: The muscular dystrophies (MDs) result from perturbations in the myofibers. These alterations are induced in part by mechanical stress due to membrane cell fragility, disturbances in mechanotransduction pathways, muscle cell physiology, and metabolism. Methods: We analyzed 290 biopsies of patients with a clinical diagnosis of muscular dystrophy. Using immunofluorescence staining, we searched for primary and secondary deficiencies of 12 different proteins, including membrane, costamere, cytoskeletal, and nuclear proteins. In addition, we analyzed calpain‐3 by immunoblot. Results: We identified 212 patients with varying degrees of protein deficiencies, including dystrophin, sarcoglycans, dysferlin, caveolin‐3, calpain‐3, emerin, and merosin. Moreover, 78 biopsies showed normal expression of all investigated muscle proteins. The frequency rates of protein deficiencies were as follows: 52.36% dystrophinopathies; 18.40% dysferlinopathies; 14.15% sarcoglycanopathies; 11.32% calpainopathies; 1.89% merosinopathies; 1.42% caveolinopathies; and 0.47% emerinopathies. Deficiencies in lamin A/C and telethonin were not detected. Conclusion: We have described the frequency of common muscular dystrophies in Mexico. Muscle Nerve, 2012

Comparison of Mutation Profiles in the Duchenne Muscular Dystrophy Gene among Populations: Implications for Potential Molecular Therapies

Novel therapeutic approaches are emerging to restore dystrophin function in Duchenne Muscular Dystrophy (DMD), a severe neuromuscular disease characterized by progressive muscle wasting and weakness. Some of the molecular therapies, such as exon skipping, stop codon read-through and internal ribosome entry site-mediated translation rely on the type and location of mutations. Hence, their potential applicability worldwide depends on mutation frequencies within populations. In view of this, we compared the mutation profiles of the populations represented in the DMD Leiden Open-source Variation Database with original data from Mexican patients (n = 162) with clinical diagnosis of the disease. Our data confirm that applicability of exon 51 is high in most populations, but also show that differences in theoretical applicability of exon skipping may exist among populations; Mexico has the highest frequency of potential candidates for the skipping of exons 44 and 46, which is different from other populations (p < 0.001). To our knowledge, this is the first comprehensive comparison of theoretical applicability of exon skipping targets among specific populations.

Dysferlin quantification in monocytes for rapid screening for dysferlinopathies.

Introduction: In this study, we determined normal levels of dysferlin expression in CD14+ monocytes by flow cytometry (FC) as a screening tool for dysferlinopathies. Methods: Monocytes from 183 healthy individuals and 29 patients were immunolabeled, run on an FACScalibur flow cytometer, and analyzed by FlowJo software. Results: The relative quantity of dysferlin was expressed as mean fluorescence intensity (MFI). Performance of this diagnostic test was assessed by calculating likelihood ratios at different MFI cut‐off points, which allowed definition of 4 disease classification groups in a simplified algorithm. Conclusion: The MFI value may differentiate patients with dysferlinopathy from healthy individuals; it may be a useful marker for screening purposes. Muscle Nerve 54: 1064–1071, 2016

Significant Association Between Variant in SGCD and Age-Related Macular Degeneration

CFH and HTRA1 genes are traditional markers of increased risk of age-related macular degeneration (AMD) across populations. Recent findings suggest that additional genes—for instance, in the dystrophin-associated protein complex—might be promising markers for AMD. Here, we performed a case-control study to assess the effect of SGCD single nucleotide polymorphisms (SNPs), a member of this protein family, on AMD diagnosis and phenotype. We performed a case-control study of an under-studied population from Hispanics in Mexico City, with 134 cases with 134 unpaired controls. Cases were 60 years or older (Clinical Age-Related Maculopathy Staging (CARMS) grade 4–5, as assessed by experienced ophthalmologists following the American Association of Ophthalmology (AAO) guidelines), without other retinal disease or history of vitreous-retinal surgery. Controls were outpatients aged 60 years or older, with no drusen or retinal pigment epithelium (RPE) changes on a fundus exam and a negative family history of AMD. We examined SNPs in the SGCD gene (rs931798, rs140617, rs140616, and rs970476) by sequencing and real-time PCR. Genotyping quality checks and univariate analyses were performed with PLINK v1.90b3.42. Furthermore, logistic regression models were done in SAS v.9.4 and haplotype configurations in R v.3.3.1. After adjusting for clinical covariates, the G/A genotype of the SGCD gene (rs931798) significantly increases the odds of being diagnosed with AMD in 81% of cases (1.81; 95% CI 1.06–3.14; p = 0.031), especially the geographic atrophy phenotype (1.82; 95% CI 1.03–3.21; p = 0.038) compared to the G/G homozygous genotype. Moreover, the GATT haplotype in this gene (rs931798, rs140617, rs140616, and rs970476) is associated with lower odds of AMD (adjusted odds ratio (OR) 0.13; 95% CI 0.02–0.91; p = 0.041). SGCD is a promising gene for AMD research. Further corroboration in other populations is warranted, especially among other Hispanic ethnicities.

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.