What is the GIS score threshold for HRD positivity?

What is the GIS score threshold for HRD positivity?

• A. 25 or higher
• B. 42 or higher
• C. 60 or higher
• D. 80 or higher

Answer: (B)

The main idea is how HRD positivity is defined using a Genomic Instability Score. HRD refers to defects in the homologous recombination repair pathway, often due to BRCA1/2 or other HR gene alterations. The GIS is a composite measure of genomic scars—loss of heterozygosity, telomeric allelic imbalance, and large-scale state transitions—that together reflect underlying repair deficiency. A GIS of 42 or higher is the established threshold used in many clinical assays to designate HRD positivity, indicating tumors likely have HR defects and may respond better to PARP inhibitors and platinum-based therapies. Scores below that threshold suggest HR proficiency. The other numerical options are not the standard cutoff used in this context.

The main idea is how HRD positivity is defined using a Genomic Instability Score. HRD refers to defects in the homologous recombination repair pathway, often due to BRCA1/2 or other HR gene alterations. The GIS is a composite measure of genomic scars—loss of heterozygosity, telomeric allelic imbalance, and large-scale state transitions—that together reflect underlying repair deficiency. A GIS of 42 or higher is the established threshold used in many clinical assays to designate HRD positivity, indicating tumors likely have HR defects and may respond better to PARP inhibitors and platinum-based therapies. Scores below that threshold suggest HR proficiency. The other numerical options are not the standard cutoff used in this context.