ISL1 common variant rs1017 is not associated with susceptibility to congenital heart disease in a Chinese population

Spotlight on Isl1: A Key Player in Cardiovascular Development and Diseases

Cardiac transcription factors orchestrate a regulatory network controlling cardiovascular development. Isl1, a LIM-homeodomain transcription factor, acts as a key player in multiple organs during embryonic development. Its crucial roles in cardiovascular development have been elucidated by extensive studies, especially as a marker gene for the second heart field progenitors. Here, we summarize the roles of Isl1 in cardiovascular development and function, and outline its cellular and molecular modes of action, thus providing insights for the molecular basis of cardiovascular diseases.

Race and genetics versus 'race' in genetics: A systematic review of the use of African ancestry in genetic studies

Social scientists have long understood race to be a social category invented to justify slavery and evolutionary biologists know the socially constructed racial categories do not align with our biological understanding of genetic variation. The completion of the Human Genome Project in 2003 confirmed humans are 99.9% identical at the DNA level and there is no genetic basis for race. A systematic review of the PubMed medical literature published since 2003 was conducted to assess the use of African ancestry to denote study populations in genetic studies categorized as clinical trials, to examine the stated rationale for its use and to assess the use of evolutionary principles to explain human genetic diversity. We searched for papers that included the terms 'African', 'African American' or 'Black' in studies of behavior (20 papers), physiological responses, the pharmacokinetics of drugs and/or disease associations (62 papers), and as a genetic category in studies, including the examination of genotypes associated with life stress, pain, stuttering and drug clearance (126 papers). Of these, we identified 74 studies in which self-reported race alone or in combination with admixture mapping was used to define the study population. However, none of these studies provided a genetic explanation for the use of the self-identified race as a genetic category and only seven proffered evolutionary explanations of their data. The concept of continuous genetic variation was not clearly articulated in any of these papers, presumably due to the paucity of evolutionary science in the college and medical school curricula.

Correlations between ISL1 rs1017 polymorphism and congenital heart disease risk: A PRISMA-compliant meta-analysis

BACKGROUND

ISL1 promotes cardiomyocyte differentiation and plays important roles in heart development. However, whether ISL1 rs1017 polymorphism is associated with the congenital heart disease (CHD) risk remains controversial.

METHODS

Five database including PubMed, Cochrane Library, ISI Web of Science, CNKI, and Wan Fang were searched by using key words "Insulin Gene Enhancer Protein ISL1" and "Single Nucleotide Polymorphism," and "Congenital Heart Disease." Five relative articles including 6 independent studies containing 2132 cases and 3812 controls were finally recruited to our study. Meta-analyses were performed by pooling odds ratios (ORs) and 95% confidence interval (CI) from included studies using STATA 12.0 software.

RESULTS

The associations between ISL1 rs1017 polymorphism and the risk of CHD were statistically significant under the allele model (T vs A; OR: 1.421; 95% CI: 1.072-1.882), heterozygous model (AT vs AA; OR: 1.342; 95% CI: 1.019-1.767), and dominant model (AT+ TT vs AA; OR: 1.466; 95% CI: 1.059-2.028). Sensitivity analysis indicated that the results were not stable. Subgroup analysis demonstrated that associations were found in Caucasians under the allele model and the heterozygous model (P < .05), but not the dominant model (P > .05).

CONCLUSION

In summary, our meta-analysis results suggest that the T allele of ISL1 rs1017 is a risk factor for CHD. However, further studies based on large sample size and multi-ethnic population should be conducted to further prove this correlation.

Genetics and genetic testing in congenital heart disease

Congenital heart defects (CHDs) are structural abnormalities of the heart and great vessels that are present from birth. The presence or absence of extracardiac anomalies has historically been used to identify patients with possible monogenic, chromosomal, or teratogenic CHD causes. These distinctions remain clinically relevant, but it is increasingly clear that nonsyndromic CHDs can also be genetic. This article discusses key morphologic, molecular, and signaling mechanisms relevant to heart development, summarizes overall progress in molecular genetic analyses of CHDs, and provides current recommendations for clinical application of genetic testing.

Cardiac stem cells: translation to human studies

The discovery of multiple classes of cardiac progenitor cells in the adult mammalian heart has generated hope for their use as a therapeutic in heart failure. However, successful results from animal models have not always yielded similar findings in human studies. Recent Phase I/II trials of c-Kit (SCIPIO) and cardiosphere-based (CADUCEUS) cardiac progenitor cells have demonstrated safety and some therapeutic efficacy. Gaps remain in our understanding of the origins, function and relationships between the different progenitor cell families, many of which are heterogeneous populations with overlapping definitions. Another challenge lies in the limitations of small animal models in replicating the human heart. Cryopreserved human cardiac tissue provides a readily available source of cardiac progenitor cells and may help address these questions. We review important findings and relative unknowns of the main classes of cardiac progenitor cells, highlighting differences between animal and human studies.

Lack of association of the 3'-UTR polymorphism (rs1017) in the ISL1 gene and risk of congenital heart disease in the white population

Congenital heart defects (CHDs) are the most prevalent of all birth defects and the leading cause of death in the first year of life. The molecular causes of most CHDs remain largely unknown. The LIM homeodomain transcriptor factor ISL1 is a marker for undifferentiated cardiac progenitor cells that give rise to both the right ventricle and the inflow and outflow tracts, which are affected by several cardiovascular malformations. Contradictory findings about the role of the ISL1 rs1017 single-nucleotide polymorphism in increasing the risk of CHD have been reported. In this study, we aimed to investigate whether the ISL1 rs1017 genetic polymorphism conferred susceptibility to CHD in the white population. In a case-control study design, 309 patients with CHD (197 men [age 21.3 ± 25.2]) and 500 healthy controls (272 men [age 15.7 ± 21.3]) were genotyped for the ISL1 rs1017 polymorphism. No significant difference in the genotype and variant allele distributions was found between patients and controls. In addition, the ISL1 rs1017 polymorphism was not associated with the risk of CHD neither overall (p = 0.7) nor stratifying the population by sex and CHD classification. In conclusion, ISL1 common variant rs1017 is not associated with increased genetic risk of CHD in the white population.