You get cramps at the piano just thinking of Belarus

You can blame it on your ancestors, none of whom could play the piano—Among the genetic price you pay for being an Ashkenazic Jew is dystonia, a disorder that cramps muscles or causes involuntary movements. It isn't fatal, but it can be a pain in the career. Ask Leon Fleisher, the concert pianist whose career was diverted by the nervous disorder. Until Fleisher regained use of his right hand, he wound up playing mostly one-handed concerti. There are some, believe it or not. Botox apparently cured the camps and he's back playing the usual repetoire with both hands—and very well indeed. We can now guess something about his genealogy he didn't know before.

It turns out, Leon can blame his genes. Judy Siegel in the Jerusalem Post reports that a genetic mutation among a small group of Jews from Belarus in the 17th century is probably the source of Fleisher's problem—and that of other Ashkenazim. They were among the survivors of pogroms at the time and their small number produced a genetic bottleneck. Someone among them had the mutation, LRRK2 G2019S, and because of the circumstances, passed it on to others in the group. In the 18th century, the Jewish population of the area exploded and so did the mutation, the reason why one in four of the Jews who can trace their ancestry to that area, have the gene.

The work was done at Albert Einstein College of Medicine in New York and is based on work at UC San Francisco.

Interestingly, the gene is also found among a group of North African Arabs, further evidence that the Ashkenazim have Middle Eastern origins. They probably moved into Europe after the destruction of the Jerusalem temple in 70 C.E., and somebody, gasp, intermarried.