Expanding the Phenotypic Spectrum of SPG7 Rare Damaging Variants: Insights From a Hungarian Cohort.

Mitochondria-associated paraplegin dysfunction is primarily linked to spastic paraplegia; however, genetic alterations in SPG7 have been associated with a broader spectrum of clinical symptoms. To identify disease-causing variants in the SPG7 gene, 437 patients with spastic ataxia, mitochondrial dysfunction-associated symptoms, or motoneuron lesions detected by EMG have been tested. We aimed to assess the clinical spectrum and determine the frequency of damaging variants within patient groups, particularly those less studied.

GDF-15 and mtDNA Deletions Are Useful Biomarkers of Mitochondrial Dysfunction in Insulin Resistance and PCOS.

There is no literature available about the growth differentiation factor-15 (GDF-15) biomarker in combination with mitochondrial DNA (mtDNA) deletions in insulin resistance (IR), and polycystic ovary syndrome (PCOS); however, it would be useful to achieve optimal metabolic status and improve pregnancy success. In this study, the role of GDF-15 and mtDNA deletions as biomarkers in the pathogenesis of IR and PCOS was investigated. In our study, 81 female patients who were treated for IR and/or PCOS and 41 healthy controls were included.

Multilevel evidence of MECP2-associated mitochondrial dysfunction and its therapeutic implications.

We present a male patient carrying a pathogenic MECP2 p. Arg179Trp variant with predominant negative psychiatric features and multilevel evidence of mitochondrial dysfunction who responded to the cariprazine treatment. He had delayed speech development and later experienced severe social anxiety, learning disabilities, cognitive slowing, and predominant negative psychiatric symptoms associated with rigidity.

Answer to Gerber et al. "Autosomal recessive pathogenic MSTO1 variants in hereditary optic atrophy".

Gal et al address the issues raised by Gerber et al and reiterate that patients in their study showed decreased Misato homolog 1 (MSTO1) mRNA and protein levels, but also confirm finding of Gerber et al that the mutation is in MSTO2p pseudogene. Whether MSTO2p variant contributes to the observed decrease in MSTO1 levels in patients remains unclear.

Genetic landscape of early-onset dementia in Hungary.

Introduction: Early-onset dementias (EOD) are predominantly genetically determined, but the underlying disease-causing alterations are often unknown. The most frequent forms of EODs are early-onset Alzheimer's disease (EOAD) and frontotemporal dementia (FTD).

Patients: This study included 120 Hungarian patients with EOD (48 familial and 72 sporadic) which had a diagnosis of EOAD (n = 49), FTD (n = 49), or atypical dementia (n = 22).

New Insights of Phospholipase A2 Associated Neurodegeneration Phenotype Based on the Long-Term Follow-Up of a Large Hungarian Family.

Introduction: Phospholipase A2-associated Neurodegeneration (PLAN) is a group of neurodegenerative diseases associated with the alterations of PLA2G6. Some phenotype-genotype association are well known but there is no clear explanation why some cases can be classified into distinct subgroups, while others follow a continuous clinical spectrum.

Methods: Long-term neurological, and psychiatric follow-up, neuropathological, radiological, and genetic examinations, were performed in three affected girls and their family.

Correlation of GAA Genotype and Acid-α-Glucosidase Enzyme Activity in Hungarian Patients with Pompe Disease.

Pompe disease is caused by the accumulation of glycogen in the lysosomes due to a deficiency of the lysosomal acid-α-glucosidase (GAA) enzyme. Depending on residual enzyme activity, the disease manifests two distinct phenotypes. In this study, we assess an enzymatic and genetic analysis of Hungarian patients with Pompe disease.

Novel dominant MPAN family with a complex genetic architecture as a basis for phenotypic variability.

Objective: Our aim was to study a Hungarian family with autosomal dominantly inherited neurodegeneration with brain iron accumulation (NBIA) with markedly different intrafamilial expressivity.

Methods: Targeted sequencing and multiplex ligation-dependent probe amplification (MLPA) of known NBIA-associated genes were performed in many affected and unaffected members of the family. In addition, a trio whole-genome sequencing was performed to find a potential explanation of phenotypic variability.

Wernicke-Korsakoff syndrome associated with mtDNA disease.

Introduction: Wernicke encephalopathy (WE) and Wernicke-Korsakoff syndrome (WKS) are well-known disorders caused by thiamine deficiency. In addition to the classical concept of these diseases, some literature data suggest a connection between mitochondrial dysfunction and WE/WKS. Psychotic disorders and WKS seem to run in families, as the deficiency of the oxidative phosphorylation can be a trigger factor in psychotic events and WE/WKS as well.

[Hereditary Parkinson’s disease as a new clinical manifestation of the damaged POLG gene].

The protein product of the nuclear-encoded POLG gene plays a key role in the maintenance of mitochondrial DNA replication, and its failure causes multi-system diseases with varying severity. The clinical spectrum is extremely wide, and the most common symptoms include ptosis, myoclonus, epilepsy, myopathy, sensory ataxia, parkinsonism, cognitive decline and infertility. Now, it is known that mitochondrial dysfunction in Parkinson's disease plays a key role in the loss of dopaminergic neurons in the substantia nigra.

Broadening the phenotype of the TWNK gene associated Perrault syndrome.

Background: Perrault syndrome is a genetically heterogenous, very rare disease, characterized clinically by sensorineural hearing loss, ovarian dysfunction and neurological symptoms. We present the case of a 33 years old female patient with TWNK-associated Perrault syndrome. The TWNK gene is coding the mitochondrial protein Twinkle and currently there are only two reports characterizing the phenotype of TWNK-associated Perrault syndrome.

The Role of Genetic Testing in the Clinical Practice and Research of Early-Onset Parkinsonian Disorders in a Hungarian Cohort: Increasing Challenge in Genetic Counselling, Improving Chances in Stratification for Clinical Trials.

The genetic analysis of early-onset Parkinsonian disorder (EOPD) is part of the clinical diagnostics. Several genes have been implicated in the genetic background of Parkinsonism, which is clinically indistinguishable from idiopathic Parkinson's disease. The identification of patient's genotype could support clinical decision-making process and also track and analyse outcomes in a comprehensive fashion.

Comprehensive Analysis of Rare Variants of 101 Autism-Linked Genes in a Hungarian Cohort of Autism Spectrum Disorder Patients.

Background: Autism spectrum disorder (ASD) is genetically and phenotypically heterogeneous. Former genetic studies suggested that both common and rare genetic variants play a role in the etiology. In this study, we aimed to analyze rare variants detected by next generation sequencing (NGS) in an autism cohort from Hungary.

[Etiological factors of sensorineural hearing loss in children after cochlear implantation].

Congenital sensorineural hearing loss is one of the most common sensory defects affecting 1-3 children per 1000 newborns. There are a lot of causes which result in congenital hearing loss, the most common is the genetic origin, but infection, cochlear malformation or other acquired causes can be reasons as well. The aim of this study was to establish the etiological factors of congenital profound sensorineural hearing loss in children who underwent cochlear implantation.

Analysis of GJB2 mutations and the clinical manifestation in a large Hungarian cohort.

Purpose: Pathogenic variants of the gap junction beta 2 (GJB2) gene are responsible for about 50% of hereditary non-syndromic sensorineural hearing loss (NSHL). In this study, we report mutation frequency and phenotype comparison of different GJB2 gene alterations in Hungarian NSHL patients.

Methods: The total coding region of the GJB2 gene was analyzed with Sanger or NGS sequencing for 239 patients with NSHL and 160 controls.

[Significance of whole exome sequencing in the diagnostics of rare neurological diseases - own experiences through a case presenting with ataxia].

Next generation sequencing (NGS) technologies reshape the diagnostics of rare neurological diseases. In the background of certain neurological symptoms, such as ataxia, many acquired and genetic causes may be present. Variations in a given gene can present with variable phenotypes, too.

Implementation of personalized medicine in Central-Eastern Europe: pitfalls and potentials based on citizen's attitude.

Objective: Next-generation sequencing is increasingly utilized worldwide as a research and diagnostic tool and is anticipated to be implemented into everyday clinical practice. Since Central-Eastern European attitude toward genetic testing, especially broad genetic testing, is not well known, we performed a survey on this issue among Hungarian participants.

Methods: A self-administered questionnaire was distributed among patients and patient relatives at our neurogenetic outpatient clinic.

Genotypic and phenotypic spectrum of the most common causative genes of Charcot-Marie-Tooth disease in Hungarian patients.

Charcot-Marie-Tooth neuropathy (CMT) is a genetically and clinically heterogeneous group of neuromuscular disorders with an overall prevalence of 1 per 2500. Here we report the first comprehensive genetic epidemiology study of Hungarian CMT patients. 409 CMT1 and 122 CMT2 patients were enrolled and genetic testing of PMP22, GJB1, MPZ, EGR2 and MFN2 genes were performed routinely.

MSTO1 is a cytoplasmic pro-mitochondrial fusion protein, whose mutation induces myopathy and ataxia in humans.

The protein MSTO1 has been localized to mitochondria and linked to mitochondrial morphology, but its specific role has remained unclear. We identified a c.22G > A (p.

Recessive mutations in MSTO1 cause mitochondrial dynamics impairment, leading to myopathy and ataxia.

We report here the first families carrying recessive variants in the MSTO1 gene: compound heterozygous mutations were identified in two sisters and in an unrelated singleton case, who presented a multisystem complex phenotype mainly characterized by myopathy and cerebellar ataxia. Human MSTO1 is a poorly studied protein, suggested to have mitochondrial localization and to regulate morphology and distribution of mitochondria. As for other mutations affecting genes involved in mitochondrial dynamics, no biochemical defects typical of mitochondrial disorders were reported.

Natural and Induced Mitochondrial Phosphate Carrier Loss: DIFFERENTIAL DEPENDENCE OF MITOCHONDRIAL METABOLISM AND DYNAMICS AND CELL SURVIVAL ON THE EXTENT OF DEPLETION.

The relevance of mitochondrial phosphate carrier (PiC), encoded by SLC25A3, in bioenergetics is well accepted. However, little is known about the mechanisms mediating the cellular impairments induced by pathological SLC25A3 variants. To this end, we investigated the pathogenicity of a novel compound heterozygous mutation in SLC25A3 First, each variant was modeled in yeast, revealing that substituting GSSAS for QIP within the fifth matrix loop is incompatible with survival on non-fermentable substrate, whereas the L200W variant is functionally neutral.

Three novel mutations and genetic epidemiology analysis of the Gap Junction Beta 1 (GJB1) gene among Hungarian Charcot-Marie-Tooth disease patients.

Pathogenic variants of the gap junction beta 1 (GJB1) gene are responsible for the Charcot-Marie-Tooth neuropathy X type 1 (CMTX1). In this study, we report the mutation frequency of GJB1 in 210 Hungarian CMT patients and the phenotype comparison between male and female CMTX1 patients. Altogether, 13 missense substitutions were found in the GJB1 gene.

Two transgenic mouse models for β-subunit components of succinate-CoA ligase yielding pleiotropic metabolic alterations.

Succinate-CoA ligase (SUCL) is a heterodimer enzyme composed of Suclg1 α-subunit and a substrate-specific Sucla2 or Suclg2 β-subunit yielding ATP or GTP, respectively. In humans, the deficiency of this enzyme leads to encephalomyopathy with or without methylmalonyl aciduria, in addition to resulting in mitochondrial DNA depletion. We generated mice lacking either one Sucla2 or Suclg2 allele.