Rosacea tends to run in families and appears to be especially prevalent among those of northern European descent, according to results of a recent survey of 600 rosacea sufferers conducted by the National Rosacea Society. Nearly 52 percent of those responding to the survey said someone else in their family has or did have rosacea, and 42 percent indicated they were of Irish, German or English ancestry.

Of those who said they have a relative with rosacea, most indicated it was someone within their immediate family. Thirty percent said their mother has rosacea, while 35 percent indicated their father, 28 percent cited a sister and 24 percent named a brother. (Percentages exceed 100 because some had more than one affected family member.)

Although rosacea was far less well known in the past, some of the respondents could trace the condition back more than one generation. Nearly 16 percent said one of their grandmothers had rosacea, while 14 percent noted that a grandfather was affected. The condition is manifesting itself in the next generation as well, as nearly 15 percent of the respondents said one or more of their children have been diagnosed with rosacea. Many also noted that an aunt, uncle or cousin has the condition.

"Especially as rosacea becomes more widely known and diagnosed, it is increasingly evident that heredity may be a factor," said Dr. Boni Elewski, vice chairman of dermatology at the University of Alabama at Birmingham. "Anyone who has a relative with rosacea would be wise to keep an eye out for the early warning signs of the disorder -- and to see a dermatologist as soon as they appear."

Data from the survey support the theory that it is especially prevalent among those who can trace their roots to the Emerald Isle. Thirty-one percent of respondents reported they had at least one parent of Irish ancestry, while only 11 percent of the U.S. population is of Irish heritage, according to the 2000 U.S. Census.

On the other hand, those of German and English descent seem to be similarly prone to rosacea as well. Forty-one percent of rosacea sufferers answering the survey said they had some German ancestry, compared to 15 percent of the U.S. population, and more than 30 percent reported an English heritage, versus 9 percent reporting English ancestry in the 2000 national census. Other nationalities in which rosacea was present at a higher rate than the ethnicity is represented in the U.S. population include Scandinavian, Scottish, French, Polish, Russian, Lithuanian, Hungarian and Czech.