Functional Annotation: David

"I have 4 genes." With DAVID: You run the list. The top cluster is "Amyloid precursor protein metabolic process" (Fold Enrichment: 45x). The second cluster is "Axon guidance" (Not significant? Maybe ignore). The third cluster is "Immune response" (Wait, microglia genes are also upregulated? That changes your hypothesis).

If you’ve just finished an RNA-seq or microarray experiment, you probably have a list of genes. It might be a short list of 50 names or a long one of 2,000. But a list is just data. The real question is: What does this list mean biologically? david functional annotation

This is the most critical step users mess up. You must tell DAVID what the "universe" is. Are you looking at the whole human genome? Or just the 10,000 genes expressed in your specific tissue? Use the whole genome for standard enrichment, but use a tissue-specific background for precision. "I have 4 genes

DAVID uses . Instead of reading genes, it reads Gene Ontology (GO) terms, pathways (KEGG), protein domains (InterPro), and disease associations. How DAVID Works (The 3-Step Magic) Step 1: Upload your list. Paste your gene symbols, Entrez IDs, or Affymetrix probes. You don't need to know the format; DAVID auto-detects it. Maybe ignore)

Your brain cannot synthesize that noise. DAVID can.

DAVID doesn't just count genes. It uses a modified Fisher Exact p-value (EASE score). Look for terms with a p-value < 0.05 after Benjamini correction (FDR). The lower the p-value, the stronger the signal.