Furthermore, the SNV analysis accurately identified known non-synonymous point mutations in well-established breast cancer driver genes like ESR1, PIK3CA, and TP53. The patterns in SNV allelic fractions also contributed to the analysis of longitudinal samples from patients, revealing, in conjunction with SCNA profiles, a prevalent high genomic similarity among tumor clones circulating across various disease time points within our cohort. The gene discussed is ESR1; the disease is neoplasm.