Myotonic Dystrophy and Cancer Susceptibility
Myotonic Dystrophy (dystrophia myotonica - DM) is a slowly progressive multi-system genetic disorder that primarily affects skeletal muscles. It is the most common form of adult muscle dystrophy, but the disease can present at any age and as early as birth. Two types of the disease have been described (type 1 and 2); they are clinically similar, with few exceptions, but genetically distinct. Prior to DCEG’s research in this area, cancer was not typically thought of as part of the disease phenotype.
When neurologists at the University of Rochester responsible for the management of DM reported the clinical impression that their patients were developing more cancer than expected, DCEG investigators in the Clinical Genetics Branch (CGB) became involved in trying to answer the question “Is myotonic dystrophy a cancer susceptibility disorder?” The investigators, first in collaboration with investigators at the Karolinska Institutet, Sweden and the University of Rochester, and later with investigators from the Statens Serum Institut, Denmark, performed quantitative analysis using data obtained from population-based diagnosis and cancer registries. They identified a highly significant, two-fold increase in the risk of all cancers combined—an excess accounted for by cancers of the colon, endometrium, ovary and brain—among DM patients.
Subsequent reports have suggested that persons with Type 1 DM are twice as likely as those with Type 2 to report a personal history of cancer, but that there is no clear correlation between nucleotide repeat length (the basic molecular abnormality in DM) and cancer risk. Ongoing investigations aim to 1) determine the genetic, clinical, and environmental predictors that may alter cancer risk for myotonic dystrophy patients; and 2) understand the biological mechanisms by which DM increases cancer risk.
For more information, contact Shahinaz Gadalla.