Publications by authors named "Fred M Vaz"

4 Publications

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Deep phenotyping classical galactosemia: clinical outcomes and biochemical markers.

Brain Commun 2020 29;2(1):fcaa006. Epub 2020 Jan 29.

Division of Metabolic Disorders, Department of Pediatrics, Emma Children's Hospital, Amsterdam, UMC, University of Amsterdam, Amsterdam, the Netherlands.

Early diagnosis and dietary treatment do not prevent long-term complications, which mostly affect the central nervous system in classical galactosemia patients. The clinical outcome of patients is highly variable, and there is an urgent need for prognostic biomarkers. The aim of this study was first to increase knowledge on the natural history of classical galactosemia by studying a cohort of patients with varying geno- and phenotypes and second to study the association between clinical outcomes and two possible prognostic biomarkers. In addition, the association between abnormalities on brain MRI and clinical outcomes was investigated. Classical galactosemia patients visiting the galactosemia expertise outpatient clinic of the Amsterdam University Medical Centre were evaluated according to the International Classical Galactosemia guideline with the addition of an examination by a neurologist, serum immunoglobulin G -glycan profiling and a brain MRI. The biomarkers of interest were galactose-1-phosphate levels and -glycan profiles, and the clinical outcomes studied were intellectual outcome and the presence or absence of movement disorders and/or primary ovarian insufficiency. Data of 56 classical galactosemia patients are reported. The intellectual outcome ranged from 45 to 103 (mean 77 ± 14) and was <85 in 62%. Movement disorders were found in 17 (47%) of the 36 tested patients. In females aged 12 years and older, primary ovarian insufficiency was diagnosed in 12 (71%) of the 17 patients. Significant differences in -glycan peaks were found between controls and patients. However, no significant differences in either -glycans or galactose-1-phosphate levels were found between patients with a poor (intellectual outcome < 85) and normal intellectual outcome (intellectual outcome ≥ 85), and with or without movement disorders or primary ovarian insufficiency. The variant patients detected by newborn screening, with previously unknown geno- and phenotypes and currently no long-term complications, demonstrated significantly lower galactose-1-phospate levels than classical patients ( < 0.0005). Qualitative analysis of the MRI's demonstrated brain abnormalities in 18 of the 21 patients, more severely in patients with a lower intellectual outcome and/or with movement disorders. This study demonstrates a large variability in clinical outcome, which varies from a below average intelligence, movement disorders and in females primary ovarian insufficiency to a normal clinical outcome. In our cohort of classical galactosemia patients, galactose-1-phosphate levels and -glycan variations were not associated with clinical outcomes, but galactose-1-phosphate levels did differentiate between classical and variant patients detected by newborn screening. The correlation between brain abnormalities and clinical outcome should be further investigated by quantitative analysis of the MR images. The variability in clinical outcome necessitates individual and standardized evaluation of all classical galactosemia patients.
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http://dx.doi.org/10.1093/braincomms/fcaa006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7425409PMC
January 2020

Response to the Letter to the Editor Regarding "Micronutrients, Essential Fatty Acids and Bone Health in Phenylketonuria".

Ann Nutr Metab 2018 16;72(1):80-81. Epub 2018 Jan 16.

Department of Pediatrics, Emma Children's Hospital, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands.

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http://dx.doi.org/10.1159/000486185DOI Listing
August 2019

Micronutrients, Essential Fatty Acids and Bone Health in Phenylketonuria.

Ann Nutr Metab 2017 24;70(2):111-121. Epub 2017 Mar 24.

Department of Pediatrics, Emma Children's Hospital, Academic Medical Center, Amsterdam, The Netherlands.

Introduction: In phenylketonuria (PKU), a natural protein-restricted dietary treatment prevents severe cognitive impairment. Nutrient deficiencies may occur due to strict diet. This study is aimed at evaluating the dietary intake and blood concentrations of micronutrients and essential fatty acids (FA), bone mineral density (BMD) and fracture history in patients on long-term dietary treatment.

Methods: Sixty early diagnosed Dutch patients (aged 1-39 years) were included in a multi-center cross-sectional study. Their dietary intake, blood concentrations of micronutrients, FA, fracture history and BMD were assessed.

Results: Selenium dietary intake and serum concentrations were low in 14 and 46% of patients, respectively. The serum 25-OH vitamin D2 + D3 concentration was low in 14% of patients while 20% of patients had a low vitamin D intake. Zinc serum concentrations were below normal in 14% of patients, despite adequate intake. Folic acid serum concentrations and intake were elevated. Despite safe total protein and fat intake, arginine plasma concentrations and erythrocyte eicosapentaenoic acid were below reference values in 19 and 6% of patients, respectively. Low BMD (Z-score <-2) was slightly more prevalent in patients, but the lifetime fracture prevalence was comparable to the general population.

Conclusions: Dutch patients with PKU on long-term dietary treatment have a near normal nutrient status. Supplementation of micronutrients of which deficiency may be deleterious (e.g., vitamin D and selenium) should be considered. BMD warrants further investigation.
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http://dx.doi.org/10.1159/000465529DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5516403PMC
March 2018

RodZ and PgsA Play Intertwined Roles in Membrane Homeostasis of and Resistance to Weak Organic Acid Stress.

Front Microbiol 2016 21;7:1633. Epub 2016 Oct 21.

Laboratory for Molecular Biology and Microbial Food Safety, Swammerdam Institute for Life Sciences, University of Amsterdam Amsterdam, Netherlands.

Weak organic acids like sorbic and acetic acid are widely used to prevent growth of spoilage organisms such as Bacilli. To identify genes involved in weak acid stress tolerance we screened a transposon mutant library of for sorbic acid sensitivity. Mutants of the () gene were found to be hypersensitive to the lipophilic weak organic acid. RodZ is involved in determining the cell's rod-shape and believed to interact with the bacterial actin-like MreB cytoskeleton. Since lies upstream in the genome of the essential gene (phosphatidylglycerol phosphate synthase) we hypothesized that expression of the latter might also be affected in mutants and hence contribute to the phenotype observed. We show that both genes are co-transcribed and that both the ::mini-Tn mutant and a conditional mutant, under conditions of minimal expression, were sensitive to sorbic and acetic acid. Both strains displayed a severely altered membrane composition. Compared to the wild-type strain, phosphatidylglycerol and cardiolipin levels were lowered and the average acyl chain length was elongated. Induction of expression from a plasmid in our transposon mutant led to no recovery of weak acid susceptibility comparable to wild-type levels. However, overexpression in the same mutant partly restored sorbic acid susceptibility and fully restored acetic acid sensitivity. A construct containing both and as on the genome led to some restored growth as well. We propose that RodZ and PgsA play intertwined roles in membrane homeostasis and tolerance to weak organic acid stress.
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http://dx.doi.org/10.3389/fmicb.2016.01633DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5073135PMC
October 2016