The Genetic Landscape and Epidemiology of Phenylketonuria.

Phenylketonuria (PKU), caused by variants in the phenylalanine hydroxylase (PAH) gene, is the most common autosomal-recessive Mendelian phenotype of amino acid metabolism. We estimated that globally 0.45 million individuals have PKU, with global prevalence 1:23,930 live births (range 1:4,500 [Italy]-1:125,000 [Japan]). Comparing genotypes and metabolic phenotypes from 16,092 affected subjects revealed differences in disease severity in 51 countries from 17 world regions, with the global phenotype distribution of 62% classic PKU, 22% mild PKU, and 16% mild hyperphenylalaninemia. A gradient in genotype and phenotype distribution exists across Europe, from classic PKU in the east to mild PKU in the southwest and mild hyperphenylalaninemia in the south. The c.1241A>G (p.Tyr414Cys)-associated genotype can be traced from Northern to Western Europe, from Sweden via Norway, to Denmark, to the Netherlands. The frequency of classic PKU increases from Europe (56%) via Middle East (71%) to Australia (80%). Of 758 PAH variants, c.1222C>T (p.Arg408Trp) (22.2%), c.1066-11G>A (IVS10-11G>A) (6.4%), and c.782G>A (p.Arg261Gln) (5.5%) were most common and responsible for two prevalent genotypes: p.[Arg408Trp];[Arg408Trp] (11.4%) and c.[1066-11G>A];[1066-11G>A] (2.6%). Most genotypes (73%) were compound heterozygous, 27% were homozygous, and 55% of 3,659 different genotypes occurred in only a single individual. PAH variants were scored using an allelic phenotype value and correlated with pre-treatment blood phenylalanine concentrations (n = 6,115) and tetrahydrobiopterin loading test results (n = 4,381), enabling prediction of both a genotype-based phenotype (88%) and tetrahydrobiopterin responsiveness (83%). This study shows that large genotype databases enable accurate phenotype prediction, allowing appropriate targeting of therapies to optimize clinical outcome.

A novel CLCN5 mutation in a boy with Bartter-like syndrome and partial growth hormone deficiency.

Dent disease is an X-linked recessive disorder affecting the proximal tubule and is characterized by low-molecular-weight proteinuria (LMWP), hypercalciuria, nephrocalcinosis/nephrolithiasis with a variable number of features of Fanconi syndrome. It is most often associated with mutations in CLCN5, which encodes the endosomal electrogenic chloride/proton exchanger ClC-5. Renal acidification abnormalities are only rarely seen in Dent disease, whereas the hypokalemic metabolic alkalosis associated with hyperreninemic hyperaldosteronism (Bartter-like syndrome) has been reported in only one patient so far. We report on a 5-year-old boy with Dent disease caused by mutation in CLCN5 gene, c.1073G>A, who presented with hypokalemic metabolic alkalosis and hyperreninemic hyperaldosteronism persisting over the entire follow-up. No mutations were found in NKCC2, ROMK, NCCT, or ClC-Kb genes. In addition, the patient exhibited growth failure associated with partial growth hormone (GH) deficiency. Coexistence of Bartter-like syndrome features with LMWP should prompt a clinician to search for Dent disease. The Bartter syndrome phenotype seen in Dent disease patients may represent a distinct form of Bartter syndrome, the exact mechanism of which has yet to be fully elucidated. Growth delay that persists in spite of appropriate therapy should raise suspicion of other causes, such as GH deficiency.

The Inflammatory and Hemostatic Cardiovascular Risk Markers During Acute Hyperglycemic Crisis in Type 1 and Type 2 Diabetes.

BACKGROUND: We analyzed cardiovascular inflammatory (C-reactive protein (CRP), interleukin 6 (IL-6)), haemostatic (homocysteine) risk markers in lean and obese patients at admission and acute hyperglicemic crisis (AHC) resolving, involving diabetic ketoacidosis (DKA) and hyperosmolar hyperglycemic state (HHS). METHODS: In that context, we included group A: N = 20 obese, B: N=20 lean patients with DKA; C: N = l0 obese, D: N=10 lean patients with HHS; E: N = 15 obese, F: N=15 lean controls. CRP IL-6, homocysteine were determined by ELISA. RESULTS: Our results showed that CRP IL-6, and homocysteine levels decreased in all groups: (A: p<0.001; B: p<0.001, C: p<0.05; D: p<0.001 mg/L), (A: p<0.001 B: p<0.001, C: p<0.001, D: p<0.01 pg/mL), (A: p<0.001, B: p <0.001; C: p<0.05, D: p=0.001 µmol/L), respectively, at resolving AHC. However, CRP persisted higher (p<0.001, p<0.01), IL-6 lower (p<0.05, p<0.001), while homocysteine levels turned out to be similar to controls. CONCLUSIONS: AHC is associated with increased inflammatory and hemostatic cardiovascular risk markers. Also, insulin therapy in AHC has had more pronounced favorable effect on IL-6 and homocystein than on CRP.

Urinary catecholamine metabolites: Capillary gas chromatography method and experience with 12 cases of neuroblastoma.

We propose a rapid, simple metodology for routine analysis of human urine to detect vanillylmandelic and homovanillic acid related to neuroblastoma. The assay were specific capillary gas chromatography with flame ionization detection. In this methodology an internal standard is used and the procedure involves ethyl ester formation without isolation of the compounds of interest. The run time is 36 minutes. We also report quantitative results for urinary vanillylmandelic and homovanillic acid in neuroblastoma patients, demonstrating the diagnostic value of this method.

Biomarkers in Serbian patients with Gaucher disease.

OBJECTIVES: The aim of the study was to evaluate the efficiency of the biomarkers chitotriosidase (Chito), total acid phosphatase (TACP), angiotensin converting enzyme (ACE) and ferritin in the diagnosis of Gaucher disease (GD) and to assess the utility of biomarkers for monitoring the effects of enzyme replacement therapy (ERT). DESIGN AND METHODS: Forty treatment-naive Gaucher patients were studied. 27/40 GP were put on ERT and monitored every 6 months. RESULTS: The baseline median values of Chito, TACP, ACE and ferritin were highly elevated in GP: 10216 nmol/mL/h, 26.1 U/L, 253 U/L, 515 µg/L, and 555 µg/L, respectively. The only significant difference between mild and moderate GP subgroups is observed for Chito activity (p=0.0116). During ERT, Chito showed the steepest decrease in regard to TACP and ACE, mainly within the first year (71.4%). CONCLUSIONS: Among these biomarkers, Chito proved to be the most useful biomarker for diagnosing GD and monitoring the ERT.

[Very long chain fatty acids in the pathogenesis, prenatal and postnatal diagnosis of X-linked adrenoleukodystrophy].

INTRODUCTION: X-linked adrenoleukodystrophy (X-ALD) is a hereditary disorder of peroxisomal metabolism, biochemically characterized by accumulation of saturated very long chain fatty acids. DIAGNOSIS OF X-ADRENOLEUKODYSTROPHY: The biochemical diagnosis of X-linked adrenoleukodystrophy is done by gas-chromatographic analysis of plasma very long chain fatty acids. Accumulation of these fatty acids is associated with cerebral demyelination, peripheral nerve abnormalities, adrenocortical insufficiency and it may play a role in the pathogenesis of the brain inflammatory response. GENETIC COUNSELING AND PRENATAL DIAGNOSIS: Detection of familial index cases is important for diagnosis of further cases of X-ALD, treatment of asynmptomatic or barely symptomatic cases to avoid or delay symptom development of heterozygotes, and for providing genetic counseling and prenatal diagnosis in high risk persons. CONCLUSION: Retroviral mediated gene transfer corrects VLCFA metabolism in several months in cultured skin fibroblasts obtained from patients with X-ALD. Therefore, there is a hope that in the near future gene therapy may become available for those affected by this severe and potentially lethal disease.