Verlander et al. (1995) developed amplification refractory mutation system (ARMS) assays for 5 known mutations in FAC and used these assays to determine the carrier frequency of the IVS4 +4 A-to-T mutation in an Ashkenazi Jewish population. Among 3,104 Jewish individuals, primarily of Ashkenazi descent, 35 IVS4 carriers were identified, for a carrier frequency of 1 in 89 (1.1%). Among 563 Iraqi Jews, no carriers of the IVS4 mutation were found. Verlander et al. (1995) suggested that the lack of the IVS4 mutation in the Iraqi Jewish population could be because the mutation originated in the Ashkenazi population after its separation from other Jewish populations.