Information on the ethnic background of the proband may provide a clue for a specific pathogenic mutation that most likely causes the disease, such as c.711 + 4A > T (IVS4 + 4A > T) in FANCC, a mutation present in homozygous state in 80% of all FA cases of Ashkenazi Jewish ancestry, and c.295C > T in FANCA, which was present homozygously in all 40 FA cases of Spanish Gypsy ancestry so far investigated. Here, FANCC is linked to Friedreich ataxia.