Epigenetic and genetic variation in GATA5 is associated with gastric disease risk
HUMAN GENETICS
Authors: Sobota, Rafal S.; Kodaman, Nuri; Mera, Robertino; Piazuelo, M. Blanca; Bravo, Luis E.; Pazos, Alvaro; Zabaleta, Jovanny; Delgado, Alberto G.; El-Rifai, Wael; Morgan, Douglas R.; Wilson, Keith T.; Correa, Pelayo; Williams, Scott M.; Schneider, Barbara G.
Abstract
Gastric cancer incidence varies considerably among populations, even those with comparable rates of Helicobacter pylori infection. To test the hypothesis that genetic variation plays a role in gastric disease, we assessed the relationship between genotypes and gastric histopathology in a Colombian study population, using a genotyping array of immune-related single nucleotide polymorphisms (SNPs). Two synonymous SNPs (rs6061243 and rs6587239) were associated with progression of premalignant gastric lesions in a dominant-effects model after correction for multiple comparisons (p = 2.63E-07 and p = 7.97E-07, respectively); effect sizes were beta = -0.863 and beta = -0.815, respectively, where beta is an estimate of effect on histopathology scores, which ranged from 1 (normal) to 5 (dysplasia). In our replication cohort, a second Colombian population, both SNPs were associated with histopathology when additively modeled (beta = -0.256, 95 % CI = -0.47, -0.039; and beta = -0.239, 95 % CI = -0.45, -0.024), and rs6587239 was significantly associated in a dominant-effects model (beta = -0.330, 95 % CI = -0.66, 0.00). Because promoter methylation of GATA5 has previously been associated with gastric cancer, we also tested for the association of methylation status with more advanced histopathology scores in our samples and found a significant relationship (p = 0.001). A multivariate regression model revealed that the effects of both the promoter methylation and the exonic SNPs in GATA5 were independent. A SNP-by-methylation interaction term was also significant. This interaction between GATA5 variants and GATA5 promoter methylation indicates that the association of either factor with gastric disease progression is modified by the other.
TBX20 loss-of-function mutation associated with familial dilated cardiomyopathy
CLINICAL CHEMISTRY AND LABORATORY MEDICINE
Authors: Zhao, Cui-Mei; Bing-Sun; Song, Hao-Ming; Wang, Juan; Xu, Wen-Jun; Jiang, Jin-Fa; Qiu, Xing-Biao; Yuan, Fang; Xu, Jia-Hong; Yang, Yi-Qing
Abstract
Background: Dilated cardiomyopathy (DCM) is a major cause of congestive heart failure, sudden cardiac death and cardiac transplantation. Aggregating evidence highlights the genetic origin of DCM. However, DCM is a genetically heterogeneous disorder, and the genetic components underlying DCM in most cases remain unknown. Methods: The coding regions and splicing junction sites of the TBX20 gene were sequenced in 120 unrelated patients with idiopathic DCM. The available close relatives of the index patient carrying an identified mutation and 300 unrelated ethnically matched healthy individuals used as controls were genotyped for TBX20. The functional characteristics of the mutant TBX20 were assayed in contrast to its wild-type counterpart by using a dual-luciferase reporter assay system. Results: A novel heterozygous TBX20 mutation, p.F256I, was identified in a family with DCM transmitted in an autosomal dominant fashion, which co-segregated with DCM in the family with complete penetrance. The missense mutation was absent in 600 control chromosomes and the altered amino acid was completely conserved evolutionarily among various species. Functional assays revealed that the mutant TBX20 had significantly diminished transcriptional activity. Furthermore, the mutation markedly reduced the synergistic activation of TBX20 with NKX2-5 or GATA4. Conclusions: This study links TBX20 loss-of-function mutation to idiopathic DCM in humans for the first time, providing novel insight into the molecular mechanism underpinning DCM.