A recently published study associates  a rare mutation in the RABL3 gene with the development of pancreatic cancer: Researchers from the U.S. and Australia report in Nature Genetics on an autosomal dominant, hereditary, truncating RABL3 mutation in patients with pancreatic ductal adenocarcinoma (PDAC). This is the most common form of pancreatic cancer and one of the most aggressive tumors with a very poor prognosis and only limited therapeutic options. About 10 % of patients with PDAC have a family history, but in most cases the underlying genetic defect is unknown.

The researchers investigated a family with five relatives affected by PDAC and performed whole-genome sequencing. This revealed that while they did not carry disease-causing variants in any of the known cancer risk genes, they all showed a truncating germline mutation in RABL3, which encodes the RAS oncogene family-like 3 (RABL3) protein. Subsequent further investigations in cells elucidated the impact of the identified mutation and a zebrafish model showed a higher rate of cancer. The functional analyses revealed that RABL3 is involved in the regulation of the RAS signaling pathway and, by interacting with another protein, regulates posttranslational modification of KRAS, a RAS GTPase. The mutation leads to accelerated prenylation of KRAS. The results of the study thus provide a novel option of genetic testing in affected families and shed new light on the biological function of RABL3 and the role of the RAS pathway in the development of cancer.