Diagnosis and monitoring of phenylketonuria by LC-MS-MS in Morocco

peer reviewedPhenylketonuria is an inherited metabolic disease, of autosomal recessive transmission, due to the enzymatic deficit of phenylalanine hydroxylase, which transforms phenylalanine into tyrosine. The deficit leads to an increase in phenylalanine and its metabolite, phenylpyruvic acid which is responsible for the toxicity and symptomatology characterized by serious neurological disorders. Through this work, we wanted to show: 1) the profile of phenylalanine concentrations in a cohort of 52 Moroccan phenylketonuric patients diagnosed in our laboratory by Tandem Mass Spectrometry coupled with HPLC; 2) The value of biological monitoring in the nutritional management of phenylketonuric patients. The results showed that phenylketonuria diagnosed in Morocco is characterized by a predominance of classic and moderate phenylketonuria in both sexes with a median concentration = 1,107 μmol/L, 26 times higher than that observed in the control group (median value = 42 μmol/L - p < 0.0001). The phenylalanine and tyrosine concentrations of 33 phenylketonuric patients regularly monitored by our laboratory highlights the effectiveness of the hypoproteic diet with a marked improvement in psychomotor development, a significant regression in behavioral disorders and an encouraging overall development of children. Conclusion: phenylketonuria is a disease that would be frequent in Morocco but it is still diagnosed at the stage of severe mental retardation. A better management of these patients could be considered when setting up a nation-wide neonatal screening program