The Prevalence of Phenylketonuria in Arab Countries, Turkey, and Iran: A Systematic Review.

BACKGROUND/OBJECTIVES: This paper seeks to identify the prevalence of Phenylketonuria (PKU) in Arab countries, Turkey, and Iran. The study reviewed the existence of comprehensive national newborn screening programs and reported consanguinity rates. METHODS: A computer based literature search was conducted using relevant keywords to retrieve studies conducted on PKU. A total of 34 articles were included. Prevalence was categorized based on the type of screening method used for PKU diagnoses. RESULTS: The prevalence of classical PKU diagnosed through a comprehensive national newborn screening program ranged from 0.005% to 0.0167%. The highest prevalence was reported in Turkey at 0.0167%, whereas the lowest prevalence was reported in the UAE, 0.005%. CONCLUSION: The findings of this review emphasize the need for the establishment of more efficient reporting systems in these countries that would help measure Disability-Adjusted Life Year (DALY) in order to estimate the overall societal burden of PKU.

Quantification of succinylacetone in urine of hepatorenal tyrosinemia patients by HPLC with fluorescence detection.

BACKGROUND: Hepatorenal tyrosinemia (HT1) is considered a treatable inherited metabolic disease, particularly when detected early in life. Succinylacetone (SA), a unique metabolic marker for HT1, is normally circulating or excreted at very low physiological concentrations and is significantly increased in HT1 patients. METHODS: We developed and validated a new method for the determination of SA in urine using high-pressure liquid chromatography with fluorescence detection. SA and its homologue 5,7-dioxooctanoic acid used as internal standard (IS) were extracted from urine, derivatized with pyrenebutyric hydrazide and separated on a C18 column within 11 min. Calibration curves were linear between 0.025 to 100 micromol/l. Within- and between-day variations were <5% and results obtained by the current method compared favorably with a reference liquid chromatography tandem mass spectrometric method. The method was applied retrospectively to the analysis of urine samples from HT1 patients. CONCLUSIONS: The method requires a minimal sample volume (0.1 ml) with simple instrumentation. The method enabled us to differentiate HT1 cases (n=14) from controls (n=104), regardless of the years of urine storage.

Determination of succinylacetone in dried blood spots and liquid urine as a dansylhydrazone by liquid chromatography tandem mass spectrometry.

Succinylacetone (SA) is a specific marker for the inherited metabolic disease, hepatorenal tyrosinemia. We developed a stable-isotope dilution liquid chromatography tandem mass spectrometry for the determination of SA in dried blood spots (DBS) and liquid urine using a (13)C(4)-SA as internal standard. SA was extracted, converted to the butyl ester and derivatized with dansylhydrazine (Dns-H). Calibration curves in DBS and urine calibrators were linear up to 100 and 30 microM, respectively. At a signal-to-noise ratio of 3, the limits of detection in DBS and urine were 0.2 and 0.005 microM, respectively. Total run time was 5 min. Intra- and inter-assay precision expressed as coefficient of variation were better than 9.1% with more than 96% recovery. The method was applied retrospectively and prospectively for the diagnosis of hepatorenal tyrosinemia and for follow-up of patients under treatment.

Tandem mass spectrometric assay of succinylacetone in urine for the diagnosis of hepatorenal tyrosinemia.

We describe an isotope dilution liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the determination of succinylacetone (SA) in urine for the diagnosis of hepatorenal tyrosinemia (HT1). The method used 15N-labeled 5(3)-methyl-3(5)-isoxazole propionic acid as internal standard. Urine samples were oximated with hydroxylamine hydrochloride at 80 degrees C, extracted by solvent-solvent extraction, and followed by derivatization of the butyl ester. The butylated isoxazole derivatives of SA and its internal standard were detected and quantified using positive ion electrospray LC-MS/MS with selected reaction monitoring. The turnaround time between injections was 10 min. Calibration curves were linear over the range of 0.0633-63.3 micromol/L. The intra- and interday assay variations were less than 7%. Mean recoveries of SA at three different concentrations ranged from 96 to 109%. During the course of this study, we identified 12 new patients with HT1 and applied this method to follow up the treatment of 4 of these patients as well as previously diagnosed HT1 patients.

Determination of urinary S-sulphocysteine, xanthine and hypoxanthine by liquid chromatography-electrospray tandem mass spectrometry.

Molybdenum cofactor and isolated sulphite oxidase deficiencies are two related rare autosomal recessive diseases characterized by severe neurological abnormalities, dislocated lens and mental retardation. Determination of three biochemical markers S-sulphocysteine (SSC), xanthine (XAN) and hypoxanthine (HXAN) in urine is essential for a definitive diagnosis and identification of the exact defect. We developed a rapid liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the analysis of SSC, XAN and HXAN in urine. The analysis was carried out in the negative-ion selected-reaction monitoring mode. The turnaround time for the assay was 7 min. Linear calibration curves for the three biomarkers were obtained in the range of 12-480 micromol/L. The intra- and inter-day assay variations were <2.5%. Mean recoveries of SSC, XAN and HXAN added to urine at two significantly different concentrations were in the range 94.3-107.3%. At a normal SSC urine excretion value of 3.2 micromol/mmol creatinine, the signal-to-noise ratio was 337:1. This stable isotope dilution LC-MS/MS method is specific, rapid and simple, and provides definitive diagnosis for molybdenum cofactor and isolated sulphite oxidase deficiencies in very small volumes of urine. We have identified seven new cases of isolated sulphite oxidase deficiency from four Saudi families and one Sudanese family.