Genetic variant raises glioma risk but improves survival
A rare genetic variant in glioma has been found to increase by 3.5 times a person's risk of developing the brain tumor. However, the study validating this link also found that carriers of the rare variant allele had a reduction in mortality of approximately 50% compared with other persons with glioma.
The large, clinic-based, case-control study focused on persons aged 18 years and older with a recent glioma diagnosis. A total of 566 glioma cases and 603 controls were genotyped for the rare susceptibility variant, rs78378222. According to investigators Kathleen M. Egan, vice chair of the Department of Cancer Epidemiology at the H. Lee Moffitt Cancer Center & Research Institute in Tampa, Florida, and colleagues, this single nucleotide polymorphism (SNP) disrupts the signal from TP53, an important tumor suppressor gene.
Although this SNP has been linked to a variety of cancers, the work of Egan's group is the first to confirm its connection to glioma. The researchers were surprised by the decreased mortality rate conferred by the variant.
“That the variant increased survival chances was an unexpected finding,” affirmed Egan in a statement from Moffitt announcing the study findings, which were published in Journal of Medical Genetics (2012;49:420-421). “It is tempting to speculate that the presence of the risk allele could direct tumor development into a less aggressive path.”