双手大拇指末端比大多数人短

BDD occurs in 0.4 percent of whites and 0.1 percent of blacks in the United States, with a higher incidence in Israel (1.6 percent of Jews, 3 percent of Arabs) and Japan
 
In a 2003 study published in The American Journal of Human Genetics, researchers reported that two mutations in the gene HOXD13 may contribute to BDD.
 
The most speculated of BDD carriers, however, is past European royalty. Despite valiant efforts, I did not find which royals exactly are implicated, so we shall briefly suspend any curiosity along those lines. The European royalty had higher than normal incidence of inbreeding due to a desire to keep their bloodlines “pure.”