Miljana Kecmanović

GSTA1, GSTM1, GSTP1 and GSTT1 polymorphisms in progressive myoclonus epilepsy: A Serbian case–control study

PURPOSE Oxidative stress is recognized as an important factor in progressive myoclonus epilepsy (PME). Genetic polymorphism of glutathione S-transferases (GSTs), which are involved in both protection from oxidative damage and detoxification, might alter the capacity for protecting tissues from exogenous and endogenous oxidants. We aimed to assess a possible association between GST polymorphism and PME, as well as, correlation between GST genotypes and oxidative phenotype in PME patients. METHODS GSTA1, GSTM1, GSTP1 and GSTT1 genotypes were determined in 26 patients with PME and 66 controls. Byproducts of protein oxidative damage (thiol groups (P-SH) and nitrotyrosine), superoxide dismutase (SOD) and glutathione peroxidase (GPX) activities were determined. RESULTS The frequency of GSTA1, GSTM1 and GSTP1 genotypes was not significantly different between PME patients and controls, while individuals with GSTT1-null genotype were at 5.44-fold higher risk of PME than carriers of GSTT1-active genotype. Moreover, significant risk of PME was obtained in carriers of both GSTT1-null and GSTM1-null genotypes. Carriers of combined GSTA1- active and GSTT1-null genotype were at highest, 7.55-fold increased risk of PME. Byproducts of protein damage did not reach statistical significance, while SOD and GPX activities were significantly higher in PME patients then in controls. When stratified according to GST genotype, P-SH groups were significantly lower only in patients with GSTT1-null genotype in comparison to carriers of active genotype. Only SOD activity was increased in GSTT1-null when compared to corresponding active genotype. CONCLUSIONS GSTT1-null genotype might be associated with the increased risk and enhanced susceptibility to oxidative stress in PME patients.

Lafora disease: Severe phenotype associated with homozygous deletion of the NHLRC1 gene

Lafora disease (LD) is a severe, autosomal recessive, latechildhood- to teenage-onset, progressive myoclonic epilepsy. It is due to either EPM2A or NHLRC1 mutations. We describe a patient with homozygous deletion encompassing the entire NHLRC1 gene, not previously reported, and with clinical course more progressive than in the most patients with NHLRC1 mutations. The diagnosis of LD in our patient was based on the typical clinic, neurophysiological presentation, as well as skin biopsy followed by molecular genetics findings. She developed normally until the age of 15, when she had her first occipital and generalized seizures. Four years after the first seizure the patient became bedridden, demented and presented with severe clinical condition. She died of pneumonia at age 20. This report is the first case of homozygosity for NHLRC1 deletion and thus adds to mutational heterogeneity of LD. Besides, it widens the spectrum of LD patients with severe phenotype and NHLRC1 mutations.

Mutational analysis of GJB1, MPZ, PMP22, EGR2, and LITAF/SIMPLE in Serbian Charcot-Marie-Tooth patients

We report the results of mutational analysis in the following genes: GJB1, MPZ, PMP22, EGR2, and LITAF/SIMPLE in 57 Charcot‐Marie‐Tooth (CMT) patients of Serbian origin without the PMP22 duplication. We found 10 different mutations in 14 CMT patients: 6 mutations in GJB1, 3 in MPZ, and 1 in PMP22. Five of six GJB1 mutations are reported for the first time, and the most frequent one appears to be a founder mutation in the Serbian population. No mutations were found in EGR2 or LITAF. Thus, GJB1 mutation analysis should be done in patients without the PMP22 duplication and male‐to‐male transmission of CMT.

HD phenocopies--possible role of Saitohin gene.

Saitohin (STH) is located in the intron of the human gene for microtubule-associated protein tau. Q7R polymorphism has been identified in the STH gene. Some neurodegenerative disorders were found to be associated with the presence of certain STH allele. This study genotyped 37 subjects with diagnosis of Huntingtons disease, but lacking mutations in HD, PRNP, JPH-3, and FTL genes for STH polymorphism. It was determined that Q allele of STH gene was over-represented in a tested group of patients (P > Pt). Over-representation of Q allele in a group of patients might be considered as genetic risk factor for HD like diseases.

Genetics of Lafora progressive myoclonic epilepsy: current perspectives

Lafora disease (LD) is a fatal neurodegenerative disorder caused by loss-of-function mutations in either laforin glycogen phosphatase gene (EPM2A) or malin E3 ubiquitin ligase gene (NHLRC1). LD is associated with gradual accumulation of Lafora bodies (LBs). LBs are aggregates of polyglucosan, a long, linear, poorly branched, hyperphosphorylated, insoluble form of glycogen. Loss-of-function mutations either in the EPM2A or in the NHLRC1 gene lead to polyglucosan formation. One hypothesis on LB formation is based on findings that laforin–malin complex downregulates glycogen synthase (GS) through malin-mediated ubiquitination, and the other one is based on findings that laforin dephosphorylates glycogen. According to the first hypothesis, polyglucosan formation is a result of increased GS activity, and according to the second, an increased glycogen phosphate leads to glycogen conformational change, unfolding, precipitation, and conversion to polyglucosan, while GS remains bound to the precipitating glycogen. In this review, we summarize all the recent findings that have important implications for the treatment of LD, all of them showing that partial inhibition of GS activity may be sufficient to prevent the progression of the disease. The current perspective in LD is high-throughput screening for small molecules that act on the disease pathway, that is, partial inhibitors of GS, which opens a therapeutic window for potential treatment of this fatal disease.

A novel P66S mutation in exon 3 of the SOD1 gene with early onset and rapid progression

Abstract Amyotrophic lateral sclerosis (ALS) is a fatal motor neuron disease in adults of unknown origin in most cases. Here we report a novel P66S mutation in exon 3 of the SOD1 gene in an apparently sporadic ALS patient with unusual early onset and rapid disease progression. Our data widen the spectrum of SOD1 mutations and clinical presentations of ALS.

A Shared Haplotype Indicates a Founder Event in Unverricht–Lundborg Disease Patients from Serbia

Unverricht–Lundborg disease (ULD) is an autosomal recessive disorder caused by dodecamer repeat expansion in the promoter region of the cystatin B (CSTB) gene in approximately 90% of the disease alleles worldwide. This study presents results of genetic findings in four Serbian unrelated patients with clinical and molecular diagnosis of ULD. Using newly established PCR protocol with betaine, we detected a homozygous expansion of dodecamer repeats in the CSTB gene in four patients with clinical diagnosis of ULD. Our results are in agreement with previous studies showing that dodecamer repeats expansion is the most common mutation associated with ULD. Haplotype analysis of eight unrelated ULD chromosomes was performed using seven markers flanking CSTB gene and one intragenic variant. We demonstrated the existence of a founder effect, strongly supported by LD calculations. Size of the minimal common haplotype implies that the most recent common ancestor of the Serbian ULD patients lived about 110 generations ago. We showed that Serbian ULD patients share the same common ancestor with patients from Baltic countries and North Africa. In the light of our data, we proposed extended minimal common haplotype, which could be considered as initial haplotype of the founder event common for Serbian, Baltic, and North African ULD patients.

Clinical and genetic data on Lafora disease patients of Serbian/Montenegrin origin

Lafora disease (LD) is an autosomal recessive, progressive disorder characterized by myoclonus and seizures, inexorable neurologic deterioration, cognitive decline and poor prognosis. LD is caused by mutations either in the EPM2A or in NHLRC1 genes. Here we report clinical and genetic findings on 14 LD patients from 10 families of Serbian/Montenegrin origin. Molecular diagnostics was performed by sequencing the coding regions of the EPM2A and NHLRC1 genes. In addition, haplotype analysis of the chromosomes carrying the two most frequent mutations (c.1048‐1049delGA and deletion of the whole NHLRC1 gene) using eight different markers flanking the NHLRC1 gene was conducted. We identified one new mutation (c.1028T>C) along with the 3 previously reported mutations (c.1048‐1049delGA, c.990delG, deletion of the whole NHLRC1 gene), all of which were located on the NHLRC1 gene. The two predominant mutations (c.1048‐1049delGA and complete NHLRC1 gene deletion) appear to be founder mutations. In addition to documenting the genetic heterogeneity observed for LD, our study suggests that mutations in the NHLRC1 gene may be a common cause of LD in the Serbian/Montenegrin population, primarily because of a founder effect.

Schizophrenia and Apolipoprotein E Gene Polymorphism in Serbian Population

ABSTRACT Apolipoprotein E (APOE) gene variants are associated with alterations in brain function and increased risk of Alzheimers disease (AD) and conflicting results have been reported in schizophrenia. Our results showed no significant differences in APOE allele or genotype frequencies between the Serbian schizophrenic patients and control individuals. However, we observed a possible association between particular subtypes of schizophrenia and APOE ε3/ε3 genotype (p = .01221) and ε4 allele showed a tendency toward positive association with responding to typical neuroleptics. APOE genotypes have no major influence on risk of schizophrenia, treatment and response to conventional antipsychotics, and age of onset in schizophrenia.

Coexistence of Unverricht‐Lundborg disease and congenital deafness: Molecular resolution of a complex comorbidity

Purpose:  We report on genetic analysis of a complex condition in a Serbian family of four siblings, wherein two had progressive myoclonic epilepsy (PME) and congenital deafness (CD), one had isolated congenital deafness (ICD), and one was healthy.