This study was conducted over a period of 1.5 years (2014–2015) at Kermanshah University of Medical Sciences, Medical Genetics Laboratory, Kermanshah, Iran. A total of 24 unrelated PKU patients from Kermanshah province, with Kurdish ethnicity and a known PAH gene causing mutations (16) enrolled in the study. The diagnosis of patients had beenwas based on clinical criteria/laboratory findings (detection of elevated Phe levels in blood samples using HPLC) and confirmation of their disease by molecular genetic analysis. After ethical approval of the project by the ethics committee of Kermanshah University of Medical Sciences (the project and ethics committee code # 89184) and obtaining the informed consent forms, the patients and 72 normal matched controls, with no genetic and congenital diseases, were tested for their mini-haplotypes (VNTR/STR) in the PAH gene.