In a study to be published in the February issue of "The Journal of Urology," researchers from Emory University School of Medicine have determined that inheritance of "mitochondrial haplogroup U" is associated with increased risk of prostate and renal cancers.
John Petros, MD, associate professor of Urology at Emory, led the study with colleagues from Emory and the Mercer University School of Medicine. Statistics from the study show that 20 million people in the United States fall into the haplogroup U category and are therefore at an increased risk for prostate or renal cancer.
Mitochondrial DNA is passed down from the mother to her children, males and females. The genetic material of the mitochondria generates energy for cells and has long been known as a mediator for the natural process of apoptosis, or cell death. In this study, Dr. Petros and his colleagues researched the inheritance pattern of mitochondria in patients with cancer.
"The study found that inheritance of mitochondrial haplogroup U is associated with an approximately 2-fold increased risk of prostate cancer and 2.5-fold increased risk of renal cancer in white North American individuals," says Dr. Petros, who also serves as co-director of the Emory Winship Cancer Institute Prostate Cancer Program and director of Urologic Research at the Atlanta Veterans Administration Medical Center. "Mitochondrial haplogroup U is found in 9.35 percent of the white United States population, which means more than 20 million individuals are in this high risk group."
By comparing the mtDNA haplotype in patients with prostate and renal cancer to that in control groups, Petros has been able to determine an association between mitochondrial genotype and cancer risk. A haplotype is a set of closely linked alleles, which are genes or variations in the sequence of genetic information on a segment of DNA. "Haplo" comes from the Greek word for "single."
The study is relegated to white North American individuals in order to provide a specific set of parameters that can be used as a control.
"In this study, we document that the distributions of mitochondrial haplogroups in white North American patients with renal and prostate cancer are different from those in a regional control group of white North American individuals," says Dr. Petros.
The study also found that a consequence of having a single mitochondrial haplogroup that is predisposed to both prostate and renal cancers is an increased risk of both cancers. A review of statistics indicates and increased incidence of renal cancer in patients with prostate cancer and an increased rate of prostate cancer in patients with renal cancer.
Mitochondrial haplogroups have been associated with other diseases. For example, the H haplogroup has been linked to late onset Alzheimer's disease and the J haplogroup is connected to Liber's hereditary optic neuropathy.
"To our knowledge," says Dr. Petros, "no previous research has evaluated the association of inherited mitochondrial haplogroup with cancer."