LDSC

LDSC estimates SNP heritability and genetic correlation from genome-wide association study (GWAS) summary statistics using LD Score regression to separate polygenic signal from confounding biases such as cryptic relatedness and population stratification.

Key Features:

• LD Score Calculation: Computes Linkage Disequilibrium (LD) Scores that quantify the number of single nucleotide polymorphisms (SNPs) in linkage disequilibrium with each SNP.
• Heritability Estimation: Estimates SNP heritability from GWAS summary statistics using LD Score regression while correcting for confounding biases.
• Genetic Correlation Analysis: Estimates genetic correlations between traits or diseases from GWAS summary statistics to assess shared genetic etiology and pleiotropy.
• Bias Correction: Differentiates inflation due to polygenicity from inflation due to confounding and uses the LD Score regression intercept as a correction factor that improves on traditional genomic control.

Scientific Applications:

• Polygenicity Assessment: Quantifies the extent of polygenicity in traits by relating GWAS test statistics to LD patterns to infer contributions of many small-effect variants.
• Bias Detection and Correction: Identifies and corrects for confounding biases such as cryptic relatedness and population stratification to refine GWAS result interpretation.
• Cross-Trait Genetic Correlation Studies: Examines genetic correlations across different traits or diseases to reveal shared biological pathways and potential shared risk factors.

Methodology:

Performs regression of GWAS test statistics on LD Scores, with the regression intercept providing a correction factor that accounts for polygenic signal and confounding biases to enable estimation of heritability and genetic correlations.