Identification and validation of key genes associated with atrial fibrillation in the elderly

Figures

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  Figure 1. The flowchart of analysis process.

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  Figure 2. Data preparation of co-expression network. (A) Clinical feature heatmap and hierarchical clustering dendrogram. The degree of heatmap from white to dark red recognizes low to high levels of clinical characteristics, and gray indicates unavailable data. The clinical feature includes sex, age, ejection fraction (EF), SR and AF. (B,C) A scale-free co-expression network estimated by the soft-thresholding powers, and the best power value β was obtained as 8.

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  Figure 3. Construction of co-expression network. (A) Nineteen co-expression modules constructed by clustering dendrograms and partitioned into different module colors (non-clustering genes shown in gray). (B) The bar plot of numbers in modules.

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  Figure 4. Correlation between co-expression modules and clinical traits. (A) Hierarchical clustering trees and heatmap of different modules. The red shows positive correlation and blue shows negative correlation. (B) Correlation relationship between each network module and traits. The values in the matrix cell indicate the correlation coefficient and the related p-value.

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  Figure 5. Correlation between green and pink modules with SR and AF. (A,B) Scatter plot in green (A) and pink (B) modules with GS (y-axis) and MM (x-axis). (C,D) The expression level of genes in green (C) and pink (D) modules. In the heatmap, green indicates the low expression and red indicates the high expression for samples. (E,F) Heatmap and clustering map of clinical traits in green (E) and pink (F) modules. In the clustering map, the varying shades of color recognizes low to high levels of expression in each clinical trait.

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  Figure 6. Go and KEGG enrichment analysis of green and pink modules. (A) GO analysis of biological process of green module. (B) GO analysis of biological process of pink module. (C) KEGG pathway analysis of green module. (D) KEGG pathway analysis of pink module. The size of the bras represents the number of genes, and the color of the dots represents the −log10(P) value, the x-axis represents the RichFactor of genes.

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  Figure 7. Hub gene map of the green module (A) and pink module (B).

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  Figure 8. Validation of hub genes in human peripheral blood leukocytes. (A) Relative mRNA expression level of nine hub genes in AF patients and controls (* P < 0.05, **P < 0.01). (B) ROC curve for five hub genes from the green module. (C) ROC curve for four hub genes from the pink module.