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A new approach for sweat analysis used in cystic fibrosis (CF) diagnosis is proposed. It consists of a noninvasive skin-wipe sampling followed by analysis of target ions using capillary electrophoresis with contactless conductometric detection (C4D). The skin-wipe sampling consists of wiping a defined skin area with precleaned cotton swab moistened with 100 μL deionized water. The skin-wipe sample is then extracted for 3 min into 400 μL deionized water, and the extract is analyzed directly. The developed sampling method is cheap, simple, fast, and painless, and can replace the conventional pilocarpine-induced sweat chloride test commonly applied in CF diagnosis. The aqueous extract of the skin-wipe sample content is analyzed simultaneously by capillary electrophoresis with contactless conductometric detection using a double opposite end injection. A 20 mmol/L L-histidine/2-(N-morpholino)ethanesulfonic acid and 2 mmol/L 18-crown-6 at pH 6 electrolyte can separate all the major ions in less than 7 min. Skin-wipe sample extracts from 30 study participants-ten adult patients with CF (25-50 years old), ten pediatric patients with CF (1-15 years old), and ten healthy control individuals (1-18 years old)-were obtained and analyzed. From the analyzed ions in all samples, a significant difference between chloride and potassium concentrations was found in the CF patients and healthy controls. We propose the use of the Cl/K ratio rather than the absolute Cl concentration and a cutoff value of 4 in skin-wipe sample extracts as an alternative to the conventional sweat chloride analysis. The proposed Cl/K ion ratio proved to be a more reliable indicator, is independent of the patient's age, and allows better differentiation between non-CF individuals and CF patients having intermediate values on the Cl sweat test. Figure New approach for cystic fibrosis diagnosis based on skin-wipe sampling of forearm and analysis of ionic content (Cl/K ratio) in skin-wipe extracts by capillary electrophoresis with contactless conductometric detection.

Objectives: Presymptomatic detection of patients with rare diseases (RD), defined by a population frequency less than 1 : 2,000, is the task of newborn screening (NBS). In the Czech Republic (CZ), currently eighteen RD are screened: phenylketonuria/hyperphenylalaninemia (PKU/HPA), congenital hypothyroidism (CH), congenital adrenal hyperplasia (CAH), cystic fibrosis (CF), medium chain acyl-CoA dehydrogenase deficiency (MCADD), long chain 3-hydroxyacyl-CoA dehydrogenase deficiency (LCHADD), very long chain acyl-CoA dehydrogenase deficiency (VLCADD), carnitine palmitoyl transferase I and II deficiency (CPTID, CPTIID), carnitine-acylcarnitine translocase deficiency (CACTD), maple syrup urine disease (MSUD), glutaric aciduria type I (GA I), isovaleryl-CoA dehydrogenase deficiency (IVA), argininemia (ARG), citrullinemia (CIT), biotinidase deficiency (BTD), cystathionine beta-synthase-deficient homocystinuria (CBSD HCU), and methylenetetrahydrofolate reductase deficiency homocystinuria (MTHFRD HCU). The aim was to analyze the prevalence of RD screened by NBS in CZ. Methods: We examined the NBS programme in CZ from 1 January 2010 to 31 December 2017, which covered 888,891 neonates. Dried blood spots were primarily analyzed using fluorescence immuno-assay, tandem mass spectrometry and fluorimetry.

Phenylketonuria is an inherited disorder of metabolism of the amino acid phenylalanine caused by a deficit of the enzyme phenylalanine hydroxylase. It is treated with a low-protein diet containing a low content of phenylalanine to prevent mental affection of the patient. Because of the restricted intake of high-biologic-value protein, patients with phenylketonuria may have lower than normal serum concentrations of pre-albumin, selenium, zinc and iron. The objective of the present study was to assess the compliance of our phenylketonuric (PKU) and hyperphenylalaninemic (HPA) patients; to determine the concentration of serum pre-albumin, selenium, zinc and iron to discover the potential correlation between the amount of proteins in food and their metabolic control. We studied 174 patients of which 113 were children (age 1-18), 60 with PKU and 53 with HPA and 61 were adults (age 18-42), 51 with PKU and 10 with HPA. We did not prove a statistically significant difference in the concentration of serum pre-albumin, zinc and iron among the respective groups. We proved statistically significant difference in serum selenium concentrations of adult PKU and HPA patients (p = 0.006; Mann-Whitney U test). These results suggest that controlled low-protein diet in phenylketonuria and hyperphenylalaninemia may cause serum selenium deficiency in adult patients.

Objective To assess the performance of a newly developed skin wipe test (SWT) for the diagnosis of cystic fibrosis (CF). Study Design Spontaneously formed sweat from the forearm was wiped by a cotton swab moistened with 100 µL of deionized (DI) water and extracted into 400 µL of DI water (SWT). The conventional Macroduct sweat test (ST) was performed simultaneously. SWT samples of 114 CF patients, 76 healthy carriers, and 58 controls were analyzed by capillary electrophoresis with contactless conductivity detection and Cl−/K+ and (Cl− + Na+)/K+ ion ratios were evaluated. Chloride concentrations from Macroduct ST were analyzed coulometrically. Results Analysis of 248 SWT samples and simultaneous Macroduct ST samples showed comparable method performance. Two ion ratios, Cl−/K+ and (Cl− + Na+)/K+, from the SWT samples and Cl− values from the ST samples were evaluated to diagnose CF. Sensitivity of the SWT method using the Cl−/K+ ratio (cutoff value 3.9) was 93.9%, compared to 99.1% when using the (Cl− + Na+)/K+ ratio (cutoff value 5.0) and 98.3% in using Macroduct Cl− (cutoff value higher or equal to 60 mmol/L). The methods' specificities were 97.8%, 94.0%, and 100.0%, respectively. Conclusions The developed SWT method with capillary electrophoretic analysis for CF diagnosis performs comparably to the conventional Macroduct ST. The SWT method is simple, fast, inexpensive, and completely noninvasive. Use of an ion ratio in obtained SWT samples is proposed as a new diagnostic parameter that shows significant promise in CF diagnostics.