C V Mihali1,2, C M Petrescu1, F C Ladaşiu-Ciolacu1, I Mândruţiu3, D Bechet3, T Nistor4, A Ardelean1,2, Gh Benga2,3,5,6,7,8. 1. "Vasile Goldiş" Western University of Arad - Institute of Life Sciences, Romania. 2. "Vasile Goldiş" Western University of Arad - Faculty of Medicine, Romania. 3. Cluj County Clinical Emergency Hospital - Laboratory of Genetic Explorations, Romania. 4. "Iuliu Haţieganu" University of Medicine and Pharmacy Cluj-Napoca, Faculty of Medicine, Romania. 5. Romanian Academy - Cluj-Napoca Branch, Romania. 6. The Gheorghe Benga Foundation, Romania. 7. Academy of Medical Sciences of Romania - Cluj-Napoca Branch, Romania. 8. The OUTNOBEL Foundation, Cluj-Napoca, Romania.
Abstract
BACKGROUND: The modern management of phenylketonuria (PKU) consists of generalized newborn screening (NBS) for hyperphenylalaninemia (HPA), confirmation of HPA in children detected in the NBS, introduction of dietary treatment in the first weeks of life, followed by monitoring the treatment of PKU for decades to maintain phenylalaninemia within the limits that will not affect the brain. The present study aimed to evaluate the usefulness of two chromatographic methodologies for determination of plasma Phe level in the routine management of PKU: the two dimensional thin layer chromatography (2D - TLC) and the high performance liquid chromatography (HPLC) procedures, respectively. MATERIAL AND METHODS: Samples of blood from 23 children with HPA detected by neonatal screening or with confirmed PKU who received treatment by low-Phe diet were analyzed to estimate the plasma Phe level by the two chromatographic procedures. RESULTS: In case of three subjects the very low concentrations of plasma Phe could not be detected by the 2D - TLC methodology, since the spot was not visible on the chromatogram. In four patients the differences between the values of plasma Phe determined by the two methodologies are not statistically significant, while in fifteen subjects the differences are highly statistically significant. This is due to the greater errors that appear in the case of 2D - TLC methodology. In the range of concentrations of plasma Phe higher than 360 μmol/L (which is the cut-off value for HPA), although in four cases there were statistically significant differences in the level of plasma Phe determined by the two methodologies, the value obtained by the 2D - TLC methodology was high enough to influence the decision of changing the diet so that HPA is kept under control. In addition, the intense spot of Phe on the 2D - TLC chromatogram may be detected even by un unexperienced laboratory specialist. CONCLUSION: The HPLC procedure for measurement of plasma Phe level is very suitable to be used in the routine management of PKU. The 2D - TLC procedure may be accompanied by relatively high errors; however, it detects patients with severe PKU.
BACKGROUND: The modern management of phenylketonuria (PKU) consists of generalized newborn screening (NBS) for hyperphenylalaninemia (HPA), confirmation of HPA in children detected in the NBS, introduction of dietary treatment in the first weeks of life, followed by monitoring the treatment of PKU for decades to maintain phenylalaninemia within the limits that will not affect the brain. The present study aimed to evaluate the usefulness of two chromatographic methodologies for determination of plasma Phe level in the routine management of PKU: the two dimensional thin layer chromatography (2D - TLC) and the high performance liquid chromatography (HPLC) procedures, respectively. MATERIAL AND METHODS: Samples of blood from 23 children with HPA detected by neonatal screening or with confirmed PKU who received treatment by low-Phe diet were analyzed to estimate the plasma Phe level by the two chromatographic procedures. RESULTS: In case of three subjects the very low concentrations of plasma Phe could not be detected by the 2D - TLC methodology, since the spot was not visible on the chromatogram. In four patients the differences between the values of plasma Phe determined by the two methodologies are not statistically significant, while in fifteen subjects the differences are highly statistically significant. This is due to the greater errors that appear in the case of 2D - TLC methodology. In the range of concentrations of plasma Phe higher than 360 μmol/L (which is the cut-off value for HPA), although in four cases there were statistically significant differences in the level of plasma Phe determined by the two methodologies, the value obtained by the 2D - TLC methodology was high enough to influence the decision of changing the diet so that HPA is kept under control. In addition, the intense spot of Phe on the 2D - TLC chromatogram may be detected even by un unexperienced laboratory specialist. CONCLUSION: The HPLC procedure for measurement of plasma Phe level is very suitable to be used in the routine management of PKU. The 2D - TLC procedure may be accompanied by relatively high errors; however, it detects patients with severe PKU.
Authors: Jerry Vockley; Hans C Andersson; Kevin M Antshel; Nancy E Braverman; Barbara K Burton; Dianne M Frazier; John Mitchell; Wendy E Smith; Barry H Thompson; Susan A Berry Journal: Genet Med Date: 2013-10-10 Impact factor: 8.822