How Can Identical Twins Be Genetically Different?
Rheumatoid Arthritis and Twins
They sleep together, eat together, and most people find it impossible to tell them apart. Identical twins who grow up together share just about everything, including their genes. But sometimes only one twin will have health problems when genetics predicts both of them should.
Scientists at the University of Michigan Medical School are just beginning to understand how two people who are so similar biologically can be so different when it comes to the development of diseases like rheumatoid arthritis.
U-M researchers have discovered three genes that are over-expressed in rheumatoid arthritis, or RA, that were not known to be associated with the disease before. They also found that non-genetic factors influenced the expression of these genes and that the expression patterns varied between identical twins where only one twin had RA. Results of the U-M study were published in the July issue of Arthritis and Rheumatism.