A biallelic multiple nucleotide length polymorphism explains functional causality at 5p15.33 prostate cancer risk...

Area of Science:

• Genetics
• Genomics
• Cancer Research

Background:

• Genome-wide association studies (GWAS) primarily focus on single-nucleotide polymorphisms (SNPs).
• Other genetic variations, like multiple nucleotide length polymorphisms (MNLPs), may also contribute to disease risk.
• The 5p15.33 region is a known prostate cancer risk locus and a strong expression quantitative trait locus (eQTL) for IRX4.

Purpose of the Study:

• To identify the causal variant regulating IRX4 transcript levels in the 5p15.33 prostate cancer risk region.
• To investigate the functional impact of a specific MNLP on gene expression and chromatin state.
• To assess the broader role of non-SNP variants in prostate cancer susceptibility.

Main Methods:

• Epigenome analysis and genome editing techniques were employed.
• Experiments were conducted in LNCaP prostate cancer cells.
• Chromatin state, androgen receptor binding, and IRX4 expression levels were measured.

Main Results:

• A biallelic MNLP (21 bp vs. 47 bp) was identified as the causal variant.
• Knock-in of the 47 bp allele in LNCaP cells altered chromatin, increased androgen receptor binding, and upregulated IRX4 expression by approximately 3-fold.
• MNLPs were implicated as strong candidate variants at additional prostate cancer risk loci.

Conclusions:

• Functional non-SNP variants, such as MNLPs, may explain a significant portion of genetic risk loci for prostate cancer.
• These findings highlight the importance of investigating diverse classes of inherited variation beyond SNPs in GWAS.
• The study has broader implications for understanding the genetic basis of other complex diseases and cancers.