Genomic DNA from homozygous patients with or without mutation was amplified in the promoter region from nucleotide 2507 to 21 and cloned between the Bgl II and Hind III multiple cloning sites in the pGL2-Basic vectors (Invitrogen, Canada inc, Burlington, Canada). All recombinants clones were verified by DNA sequencing. Luciferase assay was performed as previously described [22, 25] . Firefly luciferase reporter vector was cotransfected with constitutive expressor of Renilla luciferase, phRL-CMV (Promega, Madison, WI, USA). Firefly luciferase activity was normalized to Renilla luciferase activity.