Patricia Canto

Mutations of the 5α-reductase Type 2 gene in eight Mexican patients from six different pedigrees with 5α-reductase-2 deficiency

BACKGROUND AND OBJECTIVE Male pseudohermaphroditism due to 5α‐reductase deficiency was originally described in 1974. Recently, 5α‐reductase Type 2 gene defects have been found generally to be due to point mutations within the 5 exons of the 5α‐reductase‐2 gene. In this report, we describe the molecular study of patients with 5α‐reductase deficiency.

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

Risk factors and impact on bone mineral density in postmenopausal Mexican mestizo women.

Objective:Considering that the Mexican mestizo population seems to be the result of a genetic admixture, we proposed that further research is needed to evaluate the role of ethnicity in conjunction with health-related factors to better understand ethnic differences in bone mineral density (BMD). The aim of this study was to analyze several risk factors related to the development of osteoporosis in postmenopausal Mexican mestizo women. Methods:We included 567 postmenopausal Mexican mestizo women. A structured questionnaire for risk factors was applied and BMD was measured in total hip and lumbar spine by dual-energy x-ray absorptiometry. Nonconditional logistic regression was used to estimate crude and adjusted odds ratio. Results:Using World Health Organization criteria, 28.7% of postmenopausal women had osteoporosis, 46.4% had osteopenia, and 24.9% had normal BMD. Each clinical risk factor had a different significance for osteopenia/osteoporosis; however, duration of total breast-feeding, body mass index, and number of years since menopause remained significantly associated with osteopenia/osteoporosis after bone density was added to the nonconditional model. Interestingly, extended periods of accumulated breast-feeding for 24 and 36 months were, in both cases, significantly associated with osteopenia/osteoporosis. Conclusions:Our results confirm the importance of considering the duration of breast-feeding as an important risk factor for osteopenia/osteoporosis. In addition, we find that body mass index is positively associated with BMD. Because of the heterogeneity of the Mexican mestizo population, the risk factor for osteoporosis may not be the same in different ethnic groups.

Bone mineral density in postmenopausal Mexican-Mestizo women with normal body mass index, overweight, or obesity.

ObjectiveObesity and osteoporosis are two important public health problems that greatly impact mortality and morbidity. Several similarities between these complex diseases have been identified. The aim of this study was to analyze if different body mass indexes (BMIs) are associated with variations in bone mineral density (BMD) among postmenopausal Mexican-Mestizo women with normal weight, overweight, or different degrees of obesity. MethodsWe studied 813 postmenopausal Mexican-Mestizo women. A structured questionnaire for risk factors was applied. Height and weight were used to calculate BMI, whereas BMD in the lumbar spine (LS) and total hip (TH) was measured by dual-energy x-ray absorptiometry. We used ANCOVA to examine the relationship between BMI and BMDs of the LS, TH, and femoral neck (FN), adjusting for confounding factors. ResultsBased on World Health Organization criteria, 15.13% of women had normal BMI, 39.11% were overweight, 25.96% had grade 1 obesity, 11.81% had grade 2 obesity, and 7.99% had grade 3 obesity. The higher the BMI, the higher was the BMD at the LS, TH, and FN. The greatest differences in size variations in BMD at these three sites were observed when comparing women with normal BMI versus women with grade 3 obesity. ConclusionsA higher BMI is associated significantly and positively with a higher BMD at the LS, TH, and FN.

Molecular Analysis of the SRD5A2 in 46,XY Subjects With Incomplete Virilization: The P212R Substitution of the Steroid 5α-Reductase 2 May Constitute an Ancestral Founder Mutation in Mexican Patients

Inactivating mutations of the SRD5A2 gene result in steroid 5α-reductase 2 deficiency, an autosomal recessive disorder expressed as a male-limited disorder of sex development. Herein, genomic DNA was isolated from 11 new patients with apparent steroid 5α-reductase 2 deficiency. Coding sequence abnormalities in SRD5A2 were assessed by exon-specific polymerase chain reaction, single-stranded conformation polymorphism, and direct sequencing. Likewise, enzymatic activity of the P212R gene variant of SRD5A2 was assessed. DNA analysis revealed mutations in all patients (G115D, R171S, N193S, E197D, G203S, P212R). Three individuals were compound heterozygotes, 6 were homozygotes, and 2 more were single heterozygotes for SRD5A2 mutations; remarkably, 40% of the mutant alleles (9/22) contained the gene variant P212R. The results described in this study represent, along with our previous reports, the largest number of patients with steroid 5α-reductase 2 deficiency belonging to nonrelated families. Regarding the frequency of the p.P212R mutation in our population and its presence throughout all of our country, it allows us to hypothesize that the presence of this mutation may constitute a founder gene effect.

Molecular analysis in true hermaphrodites with different karyotypes and similar phenotypes

True hermaphroditism is characterized by the development of ovarian and testicular tissue in the same individual. Müllerian and Wolffian structures are usually present, and external genitalia are often ambiguous. The most frequent karyotype in these patients is 46,XX or various forms of mosaicism, whereas 46,XX is very rarely found. The phenotype in all these subjects is similar. We studied 10 true hermaphrodites. Six of them had a 46,XX chromosomal complement: 3 had been reared as males and 3 as females. The other 4 patients were mosaics: 3 were 46,XX/46,XY and one had a 46,XX/47,XXY karyotype. One of the 46,XX/46,XY mosaics was reared as a female, whereas the other 3 mosaics were reared as males. The sex of assignment in the 10 patients depended only on labio-scrotal differentiation. Molecular studies in 46,XX subjects documented the absence of Y centromeric sequences in all cases, arguing against hidden mosaicism. One patient presented Yp sequences (ZFY+, SRY+), which contrast with South African black 46,XX true hermaphrodites in whom no Y sequences were found. Molecular analysis in the subjects with mosaicism demonstrated the presence of Y centromeric and Yp sequences confirming the presence of a Y chromosome. Gonadal development, endocrine function, and phenotype in the 10 patients did not correlate with the presence of a Y chromosome or Y-derived sequences in the genome, confirming that true hermaphroditism is a heterogeneous condition.

Analysis of Polymorphisms in Genes (AGT, MTHFR, GPIIIa, and GSTP1) Associated with Hypertension, Thrombophilia and Oxidative Stress in Mestizo and Amerindian Populations of México

Several polymorphisms related to hypertension, thrombophilia, and oxidative stress has been associated with the development of cardiovascular disease. We analyzed the frequency of M235T angiotensinogen (AGT), A222V 5,10 methylenete-trahydrofolate reductase (MTHFR), L33P glycoprotein IIIa (GPIIIa), and I105V glutathione S-transferase P1 (GSTP1) polymorphisms in 285 individuals belonging to Mexican-Mestizo and five Amerindian population from México, by real time PCR allelic discrimination. Allele and genotype frequencies were compared using χ2 tests. All populations followed the Hardy Weinberg equilibrium for assay markers with the exception of the Triki, whose were in Hardy Weinberg dysequilibrium for the glutathione S-transferase P1 polymorphism. Interestingly, according to all the analyzed single nucleotide polymorphisms (SNPs), the Triki population was the most differentiated and homogeneous group of the six populations analyzed. A comparison of our data with those previously published for some Caucasian, Asian and Black populations showed quite significant differences. These differences were remarkable with all the Mexican populations having a lower frequency of the 105V allele of the glutathione S-transferase P1 and reduced occurrence of the 222A allele of the 5,10 methylenetetrahydrofolate reductase. Our results show the genetic diversity among different Mexican populations and with other racial groups.

Analysis of Polymorphisms in Interleukin-10, Interleukin-6, and Interleukin-1 Receptor Antagonist in Mexican-Mestizo Women with Pre-eclampsia

Due to the fact that studies seeking associations of polymorphisms in regulatory regions of cytokine genes with pre-eclampsia (PE) have not always been consistent in different population analyses, the aim of this study was to investigate the possible association between rs1800896 of interleukin-10 (IL-10), rs1800795 of interleukin-6 (IL-6), and the variable number of tandem repeats (VNTR) in intron 2 of interleukin-1 receptor antagonist (IL-1Ra), as well as gene-gene interactions between these three polymorphisms with the presence of PE in Mexican-Mestizo women and one Amerindian population from México (Maya). A case-control study was performed where 411 pre-eclamptic cases and 613 controls were genotyped. For the rs1800896 of IL-10 and rs1800795 of IL-6, we used real-time polymerase chain reaction (PCR) allelic discrimination and for the VNTR of IL-1Ra, PCR. Allele frequency differences were assessed by Chi-squared test; logistic regression was used to test for associations; a gene-gene interaction was conducted. Genotypic and allelic distribution of the polymorphisms was similar in our population. The estimated of the gene-gene interaction between the polymorphisms did not differ significantly. However, we observed important differences in the distribution of the alleles and genotypes of the three polymorphisms analyzed between Mestiza-Mexicanas and Maya-Mestizo women. In conclusion, we did not find an association between polymorphisms in IL-10, IL-6, and IL-1Ra and PE in Mexican-Mestizo and Maya-Mestizo women. To our knowledge, this is the first time that these three polymorphisms were analyzed together with gene-gene interaction in women with PE.

Endothelial Nitric Oxide Synthase Haplotypes Are Associated with Preeclampsia in Maya Mestizo Women

Preeclampsia is a specific disease of pregnancy and believed to have a genetic component. The aim of this study was to investigate if three polymorphisms in eNOS or their haplotypes are associated with preeclampsia in Maya mestizo women. A case-control study was performed where 127 preeclamptic patients and 263 controls were included. Genotyped and haplotypes for the -768T→C, intron 4 variants, Glu298Asp of eNOS were determined by PCR and real-time PCR allelic discrimination. Logistic regression analysis with adjustment for age and body mass index (BMI) was used to test for associations between genotype and preeclampsia under recessive, codominant and dominant models. Pairwise linkage disequilibrium between single nucleotide polymorphisms was calculated by direct correlation r2, and haplotype analysis was conducted. Women homozygous for the Asp298 allele showed an association of preeclampsia. In addition, analysis of the haplotype frequencies revealed that the -786C-4b-Asp298 haplotype was significantly more frequent in preeclamptic patients than in controls (0.143 vs. 0.041, respectively; OR = 3.01; 95% CI = 1.74–5.23; P = 2.9 × 10−4). Despite the Asp298 genotype in a recessive model associated with the presence of preeclampsia in Maya mestizo women, we believe that in this population the -786C-4b-Asp298 haplotype is a better genetic marker.

Impact of genetic variants of IL-6, IL6R, LRP5, ESR1 and SP7 genes on bone mineral density in postmenopausal Mexican-Mestizo women with obesity.

BACKGROUND Since obesity and osteoporosis present a high genetic predisposition and polymorphisms of IL-6, IL6R, LRP5, ESR1 and SP7 may influence the risk of both diseases, the aim of this study was to analyze the possible association of polymorphisms in these genes, as well as their haplotypes, with BMD variations in postmenopausal Mexican-Mestizo women with grade 2 or grade 3 obesity. METHODS One hundred eighty unrelated postmenopausal women with grade 2 or grade 3 obesity were included. BMD was measured in total hip and lumbar spine by dual-energy X-ray absorptiometry. DNA was obtained from blood leukocytes. Rs1800795 of IL-6, rs2228145 of IL6R, rs3736228 of LRP5, rs9340799 (XbaI) and rs2234693 (PvuII), of ESR1, rs10876432 and rs2016266, of SP7 (and their haplotypes), were studied by real-time PCR allelic discrimination. Deviations from Hardy-Weinberg equilibrium were tested. Pairwise linkage disequilibrium between single nucleotide polymorphisms was calculated by direct correlation r(2), and haplotype analysis was conducted. RESULTS Using WHO criteria, 54.5% had grade 2 obesity, and 45.5% had grade 3 obesity. Regarding DXA results, 11.1% women had osteoporosis, 41.7% had osteopenia, and 47.2% had normal BMD. Genotype and haplotype analysis showed no significant differences with BMD variations at the lumbar spine, total hip or femoral neck. CONCLUSIONS We did not find a significant association between the polymorphisms analyzed or their haplotypes and BMD variations in postmenopausal women with obesity. The higher BMD observed in women with obesity could be the result of an adaptive response to the higher loading of the skeleton.