A founder mutation in the GK1 gene is responsible for galactokinase deficiency in Roma (Gypsies).
Kalaydjieva L, Perez-Lezaun A, Angelicheva D, Onengut S, Dye D, Bosshard NU, Jordanova A, Savov A, Yanakiev P, Kremensky I, et al. Am J Hum Genet. 1999 Nov; 65(5):1299-307.