Identification of sequence variations in the GALK1 promoter region . Sequencing revealed the presence of a mutation of c.-22T>C (A). Gel electrophoresis patterns of PCR amplified DNA fragments digested with Bsg I for the confirmation of c.-22T>C (B) are shown (Lane M, DNA size marker; lane 1, C/C; lane2, T/C; lane 3, T/T). Bsg I recognizes the sequence GTGCAG (underlined in A electrophoretogram) present in wild type c.-22T, but not in c.-22C. The PCR fragment from genotype c.-22C/C, c.-22T/C and c.-22T/T will produce (à produce) one (339 bp), three (339, 267 and 72 bp) and two (267 and 72 bp) bands.