Genotypes and Haplotypes in the AXIN2 and TCF7L2 Genes are Associated With Susceptibility and With Clinicopathological Characteristics in Breast Cancer Patients.

Background: Breast cancer is a multifactorial disease whose genetic susceptibility is related to polymorphic variants of cell proliferation and migration pathways. Variants in AXIN2 and TCF7L2 in the Wnt-ß catenin pathway have been associated with different types of cancer; however, little is known about its role in breast cancer. This study tests the hypothesis of links between AXIN2 rs1133683 and rs2240308, and TCF7L2 rs7903146 and rs12255372 variants in breast cancer. Methods: Peripheral blood samples were obtained from 404 women (202 patients and 202 control females). The polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) methodology was used to identify the gene variants. Results: The AXIN2 rs2240308 (C > T), and TCF7L2 rs7903146 (C > T) and rs12255372 (G > T) variants were associated with breast cancer and with age, TNM stage, and histologic-molecular subtype (p = 0.001). Likewise, the haplotype T-T in the TCF7L2 gene (rs7903146-rs12253372) was significantly related with breast cancer (OR = 2.66, 95%, CI = 1.64-4.30, p = 0.001). Conclusion: Our data show a link between AXIN2 rs2240308 and TCF7L2 rs7903146 and rs12255372 variants in breast cancer, and speculate this may be important in pathogenesis.

Evolution and genomics of the human brain. / Evolución y genómica del cerebro humano.

Most living beings are able to perform actions that can be considered intelligent or, at the very least, the result of an appropriate reaction to changing circumstances in their environment. However, the intelligence or intellectual processes of humans are vastly superior to those achieved by all other species. The adult human brain is a highly complex organ weighing approximately 1500g, which accounts for only 2% of the total body weight but consumes an amount of energy equal to that required by all skeletal muscle at rest. Although the human brain displays a typical primate structure, it can be identified by its specific distinguishing features. The process of evolution and humanisation of the Homo sapiens brain resulted in a unique and distinct organ with the largest relative volume of any animal species. It also permitted structural reorganization of tissues and circuits in specific segments and regions. These steps explain the remarkable cognitive abilities of modern humans compared not only with other species in our genus, but also with older members of our own species. Brain evolution required the coexistence of two adaptation mechanisms. The first involves genetic changes that occur at the species level, and the second occurs at the individual level and involves changes in chromatin organisation or epigenetic changes. The genetic mechanisms include: a) genetic changes in coding regions that lead to changes in the sequence and activity of existing proteins; b) duplication and deletion of previously existing genes; c) changes in gene expression through changes in the regulatory sequences of different genes; and d) synthesis of non-coding RNAs. Lastly, this review describes some of the main documented chromosomal differences between humans and great apes. These differences have also contributed to the evolution and humanisation process of the H. sapiens brain.

Molecular thrombophilic profile in Mexican patients with idiopathic recurrent pregnancy loss.

Idiopathic recurrent pregnancy loss (IRPL) is defined by three or more consecutive miscarriages occurring before the twentieth week of gestation as a result of unidentified etiological factors. The results of previous studies have indicated that prothrombotic factors play a pathogenic role in early and late pregnancy. This study aimed to identify inherited prothrombotic and hypofibrinolytic risk factors in Mexican-Mestizo patients with IRPL. Fifty-six women with IRPL and 50 control women with at least two full-term pregnancies and no history of RPL were included in this case-control study. Four prothrombotic (F5 G1691A, F2 G20210A, MTHFR C677T-A1298C) and one hypofibrinolytic (PAI1 4G/5G) restricted fragment length polymorphisms were subjected to molecular analysis. In the case of hypofibrinolytic ACE Ins/Del (I/D), identification was performed by direct PCR. The independent risk correlated with the presence of polymorphisms in IRPL patients was estimated using odds ratio (OR) with a 95% confidence interval (CI). MTHFR 677TT was the most frequent prothrombotic factor in the IRPL group (23%), followed by the compound-heterozygous C677T-A1298C (16%) and heterozygous F2 20210GA (3.6%). The heterozygous ACE I/D (62%) was the main hypofibrinolytic risk factor of IRPL, followed by the homozygote PAI1 4G/4G (18%). The ACE I/D polymorphism was the only significantly different factor among the cases and controls. The dominant genetic model D/D+I/D vs I/I showed an OR (95%CI) of 2.89 (1.22-6.89) and P = 0.019 in Mexican-Mestizo women. The results of this study support an association between the ACE I/D polymorphism and IRPL risk in a Mexican population.

TCF7L2 and CCND1 polymorphisms and its association with colorectal cancer in Mexican patients.

Accumulative evidence suggests that alterations due to mutations or genetic polymorphisms in the TCF7L2 and CCND1 genes, which are components of the Wnt signaling pathway, contributes to carcinogenesis. The present study was designated to clarify whether common single nucleotide polymorphisms (SNPs) of the transcription factor 7- like 2 (TCF7L2) and cyclin D1 (CCND1) genes are associated with colorectal cancer risk in Mexican patients. A case-control study including 197 colorectal cancer patients and 100 healthy subjects was conducted in a Mexican population. Identification of polymorphisms was made by the polymerase chain reaction-restriction fragment length polymorphism methodology. The association was calculated by the odds ratio (OR) test. The results demonstrate that patients with the T/T genotype for the rs12255372 polymorphism of the TCF7L2 gene present an increased colorectal cancer risk (OR=2.64, P=0.0236). Also, the risk analysis for Tumor-Nodule-Metastasis (TNM) stage and tumor location showed association with this polymorphism under the over-dominant model of inheritance (OR=1.75, P=0.0440). A similar relation was observed for the genotype T/T of the rs7903146 polymorphism and the rectal location of cancer (OR=7.57, P=0.0403). For the rs603965 polymorphism of the CCND1 gene, we observed a protection effect for the colon cancer location under the dominant model (OR=0.49, P=0.0477). These results reveal a significant role of the analyzed polymorphisms in the TCF7L2 and CCND1 genes on the susceptibility or protection for developing colorectal cancer in the Mexican population.

Epigenetic mechanisms in the development of memory and their involvement in certain neurological diseases. / Mecanismos epigenéticos en el desarrollo de la memoria y su implicación en algunas enfermedades neurológicas.

INTRODUCTION: Today, scientists accept that the central nervous system of an adult possesses considerable morphological and functional flexibility, allowing it to perform structural remodelling processes even after the individual is fully developed and mature. In addition to the vast number of genes participating in the development of memory, different known epigenetic mechanisms are involved in normal and pathological modifications to neurons and therefore also affect the mechanisms of memory development. DEVELOPMENT: This study entailed a systematic review of biomedical article databases in search of genetic and epigenetic factors that participate in synaptic function and memory. CONCLUSIONS: The activation of gene expression in response to external stimuli also occurs in differentiated nerve cells. Neural activity induces specific forms of synaptic plasticity that permit the creation and storage of long-term memory. Epigenetic mechanisms play a key role in synaptic modification processes and in the creation and development of memory. Changes in these mechanisms result in the cognitive and memory impairment seen in neurodegenerative diseases (Alzheimer disease, Huntington disease) and in neurodevelopmental disorders (Rett syndrome, fragile X, and schizophrenia). Nevertheless, results obtained from different models are promising and point to potential treatments for some of these diseases.

Neuhauser syndrome: a rare association of megalocornea and mental retardation. Review of the literature and further phenotype delineation.

Megalocornea can be observed as an isolated abnormality that is inherited by an X-linked mechanism, or it can be associated with other entities. Megalocornea-mental retardation syndrome, also known as Neuhauser syndrome, is a rare autosomal recessive congenital disorder that presents with megalocornea, mental retardation, hypotonia, and facial dysmorphism, among other signs. With the report of this new case, and after an extensive review of the literature, we attempt to delineate the Neuhauser syndrome phenotype.