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The Multiple Testing Problem

GWAS tests millions of SNPs simultaneously. With a standard threshold of p < 0.05, most "hits" would be noise. Adjust the parameters to see how many false positives you'd expect.

100,000
0.05
~5,000 false positives
Expected under the null hypothesis

Reading a Manhattan Plot

Each dot is one SNP. The x-axis is chromosomal position. The y-axis is −log₁₀(p-value). Click peaks to learn about associated loci.

Click a peak above the threshold line to explore it

The QQ Plot

A quantile-quantile plot compares observed p-values to what we'd expect by chance. Deviation only in the tail = real signal. Early deviation = systematic inflation (confounding).

Building a Polygenic Score

A polygenic score (PGS) sums up thousands of small genetic effects. Toggle risk alleles on or off to see your cumulative score — and corresponding disease risk for dilated cardiomyopathy (DCM).

DCM study: 14,256 cases, 1,199,156 controls, 80 loci identified.

PGS = 0.00
Select risk alleles above to build your score
chaek.org · Human Genetics Ch.18