Publications by authors named "Tomas Honzik"

Article Synopsis
  • Mitochondrial diseases are serious inherited disorders primarily affecting children, linked to issues with the mitochondrial energy production system known as oxidative phosphorylation (OXPHOS).
  • While mitochondrial DNA mutations account for only 25% of pediatric cases and next-gen sequencing can be inconclusive, biochemical methods remain important for accurate diagnosis.
  • The study introduced a method for isolating and cryopreserving peripheral blood mononuclear cells (PBMCs) from children's blood, achieving a 72% diagnosis confirmation rate in mitochondrial disease cases using high-resolution oxygraphy, though false negatives occurred in 13% of instances.
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Background: Transport protein particle (TRAPP) is a multiprotein complex that functions in localising proteins to the Golgi compartment. The TRAPPC11 subunit has been implicated in diseases affecting muscle, brain, eye and to some extent liver. We present three patients who are compound heterozygotes for a missense variant and a structural variant in the gene.

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Carbamoyl phosphate synthetase 1 (CPS1) and ornithine transcarbamylase (OTC) deficiencies are rare urea cycle disorders, which can lead to life-threatening hyperammonemia. Liver transplantation (LT) provides a cure and offers an alternative to medical treatment and life-long dietary restrictions with permanent impending risk of hyperammonemia. Nevertheless, in most patients, metabolic aberrations persist after LT, especially low plasma citrulline levels, with questionable clinical impact.

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Limb girdle muscular dystrophies (LGMD) are a genetically heterogeneous group of muscular dystrophies. The study presents an overview of molecular characteristics of a large cohort of LGMD patients who are representative of the Czech LGMD population. We present 226 LGMD probands in which 433 mutant alleles carrying 157 different variants with a supposed pathogenic effect were identified.

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Article Synopsis
  • AADC deficiency is a rare genetic disorder that impacts the production of neurotransmitters like dopamine, norepinephrine, epinephrine, and serotonin, diagnosed via CSF/plasma analysis, AADC activity measurement, and genetic testing for the DDC gene.
  • In a study involving 348 patients, researchers identified 26 new DDC variants and analyzed their prevalence, finding that a specific splice variant, c.714+4A>T, was the most common, particularly prevalent in Taiwan and China.
  • The majority of identified genotypes were classified as pathogenic or likely pathogenic, with only one benign variant reported, and most AADC protein variants impacted protein function significantly based on their structural characteristics.*
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Leber hereditary optic neuropathy is a primary mitochondrial disease characterized by acute visual loss due to the degeneration of retinal ganglion cells. In this study, we describe a patient carrying a rare missense heteroplasmic variant in , NC_012920.1:m.

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PMM2-CDG is the most common defect among the congenital disorders of glycosylation. In order to investigate the effect of hypoglycosylation on important cellular pathways, we performed extensive biochemical studies on skin fibroblasts of PMM2-CDG patients. Among others, acylcarnitines, amino acids, lysosomal proteins, organic acids and lipids were measured, which all revealed significant abnormalities.

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Article Synopsis
  • Regulation of hydrogen sulfide (HS) homeostasis in humans is not well understood, prompting a study of patients with rare enzyme deficiencies related to HS synthesis and catabolism.
  • Analysis of sulfur compounds in these patients revealed unexpected results, such as increased bioavailable sulfide levels in those with cystathionine β-synthase (CBS) deficiency, suggesting compensatory mechanisms at play.
  • The study highlights the complexity of HS regulation, showing that various genetic defects can lead to altered levels of sulfur compounds, underscoring the need for a thorough understanding of HS homeostasis in metabolic disorders.
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In this study, we report on a novel heteroplasmic pathogenic variant in mitochondrial DNA (mtDNA). The studied patient had myoclonus, epilepsy, muscle weakness, and hearing impairment and harbored a heteroplasmic m.8315A>C variant in the MTTK gene with a mutation load ranging from 71% to >96% in tested tissues.

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Introduction: Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by deficits in social communication and the presence of restricted interests and repetitive behaviors. Transient hyperphosphatasemia of infancy and early childhood (THI) is a benign laboratory disorder characterized by transiently extremely elevated activity of serum alkaline phosphatase (S-ALP).

Case Report: We present a 21-month-old girl with a right leg limp, most probably due to reactive arthritis after febrile viral infection, and deterioration of psychomotor development with concomitant transient elevation of S-ALP (61.

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Article Synopsis
  • Glycine encephalopathy (NKH) is a genetic neurometabolic disorder that can lead to a range of symptoms, from severe epileptic seizures in infants to psychiatric issues, highlighting the need for better diagnosis and understanding of the disease's severity.
  • Research involved analyzing data from 25 individuals with NKH to identify symptom onset and diagnostic indicators, discovering specific glycine ratio thresholds that can help differentiate between severe and attenuated forms of the disorder.
  • The study not only identifies new genetic variants associated with NKH but also proposes a model based on multiple factors to predict the disease's severity, which could enhance patient management and treatment strategies.
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The aim of this study was to describe the ocular phenotype in a case with Kearns-Sayre syndrome (KSS) spectrum and to determine if corneal endothelial cell dysfunction could be attributed to other known distinct genetic causes. Herein, genomic DNA was extracted from blood and exome sequencing was performed. Non-coding gene regions implicated in corneal endothelial dystrophies were screened by Sanger sequencing.

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Long chain 3-hydroxyacyl-CoA dehydrogenase deficiency (LCHADD/MTPD) and medium chain acyl-CoA dehydrogenase deficiency (MCADD) were included in the expanded neonatal screening program (ENBS) in Czechia in 2009, allowing for the presymptomatic diagnosis and nutritional management of these patients. The aim of our study was to assess the nationwide impact of ENBS on clinical outcome. This retrospective study analysed acute events and chronic complications and their severity in pre-ENBS and post-ENBS cohorts.

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Inherited disorders of neurotransmitter metabolism are rare neurodevelopmental diseases presenting with movement disorders and global developmental delay. This study presents the results of the first standardized deep phenotyping approach and describes the clinical and biochemical presentation at disease onset as well as diagnostic approaches of 275 patients from the registry of the International Working Group on Neurotransmitter related Disorders. The results reveal an increased rate of prematurity, a high risk for being small for gestational age and for congenital microcephaly in some disorders.

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Objectives: X-linked adrenoleukodystrophy (X-ALD) causes cerebral adrenoleukodystrophy (cALD), myelopathy and/or adrenal insufficiency in males, and myelopathy/peripheral neuropathy in females. These distinct phenotypes are scarcely linked to a specific mutations. The objective herein was to find a link between the phenotype with the genotype mutation, serum very long-chain fatty acids (VLCFA), and the diet with Lorenzo´s and GTO oils in hemizygous males and heterozygous females.

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PMM2-CDG is the most common congenital disorder of glycosylation (CDG) accounting for almost 65% of known CDG cases affecting N-glycosylation. Abnormalities in N-glycosylation could have a negative impact on many endocrine axes. There is very little known on the effect of impaired N-glycosylation on the hypothalamic-pituitary-adrenal axis function and whether CDG patients are at risk of secondary adrenal insufficiency and decreased adrenal cortisol production.

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Article Synopsis
  • ALG3-CDG is a rare disease caused by problems in the ALG3 gene, leading to severe health issues like neurological and heart problems.
  • A 23-month-old girl with ALG3-CDG showed symptoms like developmental delays, seizures, and eye problems, along with some physical abnormalities from birth.
  • Researchers found new genetic changes in her ALG3 gene, adding to what we know about this disease and its links to vision problems.
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The mitochondrial respiratory chain (MRC) complex III (CIII) associates with complexes I and IV (CI and CIV) into supercomplexes. We identified a novel homozygous missense mutation (c.665G>C; p.

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Isolated methylmalonic acidaemia (MMA) and propionic acidaemia (PA) are rare inherited metabolic diseases. Six years ago, a detailed evaluation of the available evidence on diagnosis and management of these disorders has been published for the first time. The article received considerable attention, illustrating the importance of an expert panel to evaluate and compile recommendations to guide rare disease patient care.

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Inherited monoamine neurotransmitter disorders (iMNDs) are rare disorders with clinical manifestations ranging from mild infantile hypotonia, movement disorders to early infantile severe encephalopathy. Neuroimaging has been reported as non-specific. We systematically analyzed brain MRIs in order to characterize and better understand neuroimaging changes and to re-evaluate the diagnostic role of brain MRI in iMNDs.

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