Study Reveals Distinct Genetic Patterns of Germline Cancer Risk and Somatic Tumor Variants

According to a new study published in The American Journal of Human Genetics, the genetic changes associated with germline cancer risk are often different from the variants found in tumors.

A research team led by first author Suhasini Lulla and corresponding author Sharon Plon, MD, PhD, FACMG, compared germline cancer-predisposition variants with tumor-associated mutations across 40 tumor suppressor genes, a group of genes that help protect the body against cancer. Despite the expected shared functional mechanism in cancer development, fewer than 10% of variants were found in both germline and somatic tumor datasets.

Researchers found that germline (hereditary) cancer-predisposition variants and somatic tumor-associated mutations often follow distinct patterns. In many cases, those differences appeared to be influenced by factors such as environmental exposures, as well as the biology of specific genes and tissues.

The findings add important nuance to the classic "two-hit" model of cancer development, which proposes that tumor suppressor genes typically require two inactivating genetic changes before cancer can develop. Rather than showing similar mutational patterns, the study found that germlineand somatic variants often represent distinct genetic landscapes shaped by different biological and environmental forces.

The researchers say the results have important implications for cancer genetics, suggesting that tumor sequencing data may have limited utility as evidence for germline tumor suppressor gene variant classification. A better understanding of these differences on a gene-by-gene basis may help researchers and clinicians improve how cancer-related genetic variants are interpreted and classified in the future.

Read the study: https://www.cell.com/ajhg/fulltext/S0002-9297(26)00304-6