Fine-mapping CASP8 risk variants in breast cancer

Area of Science:

• Genetics
• Oncology
• Human Genetics

Background:

• Genome-wide and candidate gene studies implicate the caspase-8 (CASP8) gene in breast cancer risk.
• Previous meta-analyses consistently highlight CASP8's importance in breast cancer susceptibility.
• The CASP8 gene region is located on chromosome 2q33-q34.

Purpose of the Study:

• To define a breast cancer risk haplotype within the CASP8 gene region.
• To map the CASP8 gene region to identify underlying susceptibility variants.
• To investigate genetic factors contributing to breast cancer risk.

Main Methods:

• Genotyped 45 tagging single nucleotide polymorphisms (tSNPs) in the expanded CASP8 region.
• Utilized two independent datasets from the UK and US, comprising 3,888 breast cancer cases and controls.
• Performed SNP and haplotype association tests using Monte Carlo-based methods.

Main Results:

• Identified a significant three-SNP haplotype (rs3834129, rs6723097, rs3817578) associated with breast cancer (P < 5 × 10(-6)).
• The risk haplotype showed a dominant risk ratio of 1.28 (95% CI: 1.21-1.35) and a frequency of 0.29 in controls.
• This risk haplotype association was highly consistent across both study sites and with prior research.

Conclusions:

• The identified three-SNP haplotype represents the most precise characterization to date of the chromosomal region containing breast cancer susceptibility variants.
• Characterizing this risk haplotype provides a robust foundation for subsequent resequencing studies to pinpoint the specific risk variant.
• Identifying the underlying risk variant may enhance individual breast cancer risk prediction and offer new insights into breast carcinogenesis.