Genetic And Environmental Factors May Cause Vitiligo

Vitiligo Will Be Caused By Genetic And Environmental Factors
Vitiligo Will Be Caused By Genetic And Environmental Factors

A pair of new journal articles by researchers at the University of Colorado School of Medicine indicate that both genetic and environmental factors play significant roles in the onset of vitiligo, an autoimmune disease that results in the loss of color in blotches of skin. The findings also show that while the tools for scientific understanding of the genetic basis of a complex disease like vitiligo have advanced, there are still many other as-yet unidentified factors that contribute to vitiligo’s onset.

Vitiligo common risk

Spritz and his co-authors reviewed two types of vitiligo cases simplex and multiplex. In most instances, vitiligo appears in individuals with no family history of the disease, which are referred to as the simplex cases. In the multiplex cases, there are other family members with vitiligo. A paper by Spritz and his co-authors in the American Journal of Human Genetics combines the 50 vitiligo common risk variants together to make a vitiligo “genetic risk score,” and then compare the simplex and multiplex cases.

“The paper could be called a first chapter to the ‘vitiligo instruction manual,'” Spritz said. “They find that the vitiligo genetic risk score is higher in the multiplex families than in the simplex cases; also the more affected relatives in the family the higher the risk score. That means that vitiligo in multiplex families and simplex cases is basically the same; but that the families with multiple affect relatives have higher genetic risk. That means that the same treatments probably will be effective in both types of cases.”

That finding complicates the ability of scientists and physicians; who want to predict who might be affect by vitiligo. Simplex cases and multiplex cases seem to mostly involve the same underlying genetic variants; hence with different patients just having different combinations of genetic risk variants. Such a finding complicates the use of predictive personalize medicine to diagnose and treat complex diseases, Spritz said, because there doesn’t appear to be genetically defined patient subgroups; so with different underlying biology who might thus respond differentially to personalized treatments.

Human medical genetics

In addition to Spritz, the authors of the article are Genevieve H.L. Roberts, a PhD candidate in human medical genetics and genomics at CU Anschutz Medical Campus at the time of writing the article; Subrata Paul, a PhD candidate in statistics at CU Denver; Daniel Yorgov, PhD, assistant professor of applied statistics at Purdue University Fort Wayne; and Stephanie Santorico, PhD, professor and director of statistical programs at the Colorado School of Public Health.

“Vitiligo converted from being principally a 02 principally an adult onset disease over the period 1970-2004,” Spritz said. “That is amazing. Our genes haven’t changed over that period of time; altered genes or even gene effects don’t seem to be the cause. This must reflect some beneficial environmental change that somehow delays or reduces vitiligo triggering in people who are genetically susceptible. What was it? We don’t know.”

The authors write that one or more environmental changes seem to have alter triggering of vitiligo and delayed disease onset, with a similar pattern both in North America and in Europe. “While this apparently beneficial change provides an extraordinary inroad to discover vitiligo environmental triggers; the number of potential candidates is enormous,” Spritz and his colleagues write. In addition to Spritz, the authors of the letter in Journal of Investigative Dermatology, are Ying Jin, MD, PhD, senior instructor of pediatrics, and Stephanie Santorico, PhD, professor and director of statistical programs at the Colorado School of Public Health.