Correlation between genotype and phenotype in patients with phenylalanine hydroxylase deficiency　SUN Yun, ZHANG Jingjing, SUN Yijun，CHEN Yuling, ZHANG Jin, HUANG Meilian, LIANG Xiaowei, JIANG Tao (Neonatal Screening Center, Nanjing Maternal and Child Health Hospital Affiliated to Nanjing Medical University, Nanjing 210004, Jiangsu, China)