THE AIM was focused on molecular analysis of the selected genes associated with autosomal recessi... more THE AIM was focused on molecular analysis of the selected genes associated with autosomal recessive Charcot-Marie-Tooth neuropathies (AR-CMT) and construction of a molecular diagnostic algorithm in this group of disorders in the Polish population. Material and methods: We analyzed a group of 138 subjects from 62 families with probably autosomal recessive inheritance and the control group of 52 individuals. The studies covered molecular genetic analysis of PMP22 gene dosage (real-time polymerase chain reaction and polymerase chain reaction restriction fragments length polymorphisms), analysis of coding regions of the GDAP1, PRX, EGR2 and CTDP1 genes using: mutation screening (single strand conformation polymorphism and heteroduplex analysis), sequencing and bioinformatics approach to the gene sequence variants. Results: Thirty sequence variants have been found in the analysed genes, 5 pathogenic mutations in the GDAP1 gene and 2 pathogenic mutations in the PRX gene. On the basis of bioinformatic analysis other nucleotide changes have been categorized as harmless polymorphisms and variants of unknown pathogenic effect. Conclusions: This is the first study focused on the autosomal recessive Charcot-Marie-Tooth disease in the Polish population. Our results show the difficulties in the interpretation of the pathogenic effect of the sequence variants (pathogenic mutation or polymorphism) which is essential for molecular diagnostics in CMT disease.
Charcot–Marie–Tooth disorders (CMT) represent a highly heterogeneous group of diseases of the per... more Charcot–Marie–Tooth disorders (CMT) represent a highly heterogeneous group of diseases of the peripheral nervous system in which more than 100 genes are involved. In some CMT patients, a few weak sequence variants toward other CMT genes are detected instead of one leading CMT mutation. Thus, the presence of a few variants in different CMT-associated genes raises the question concerning the pathogenic status of one of them. In this study, we aimed to analyze the pathogenic effect of c.664G>A, p.Glu222Lys variant in the GDAP1 gene, whose mutations are known to be causative for CMT type 4A (CMT4A). Due to low penetrance and a rare occurrence limited to five patients from two Polish families affected by the CMT phenotype, there is doubt as to whether we are dealing with real pathogenic mutation. Thus, we aimed to study the pathogenic effect of the c.664G>A, p.Glu222Lys variant in its natural environment, i.e., the neuronal SH-SY5Y cell line. Additionally, we have checked the patho...
Charcot-Marie-Tooth disease (CMT) is a heritable neurodegenerative disease that displays great ge... more Charcot-Marie-Tooth disease (CMT) is a heritable neurodegenerative disease that displays great genetic heterogeneity. The genes and mutations that underlie this heterogeneity have been extensively characterized by molecular genetics. However, the molecular pathogenesis of the vast majority of CMT subtypes remains terra incognita. Any attempts to perform experimental therapy for CMT disease are limited by a lack of understanding of the pathogenesis at a molecular level. In this study, we aim to identify the molecular pathways that are disturbed by mutations in the gene encoding GDAP1 using both yeast and human cell, based models of CMT-GDAP1 disease. We found that some mutations in GDAP1 led to a reduced expression of the GDAP1 protein and resulted in a selective disruption of the Golgi apparatus. These structural alterations are accompanied by functional disturbances within the Golgi. We screened over 1500 drugs that are available on the market using our yeast-based CMT-GDAP1 model....
Charcot–Marie–Tooth (CMT) disease encompasses a group of rare disorders that are characterized by... more Charcot–Marie–Tooth (CMT) disease encompasses a group of rare disorders that are characterized by similar clinical manifestations and a high genetic heterogeneity. Such excessive diversity presents many problems. Firstly, it makes a proper genetic diagnosis much more difficult and, even when using the most advanced tools, does not guarantee that the cause of the disease will be revealed. Secondly, the molecular mechanisms underlying the observed symptoms are extremely diverse and are probably different for most of the disease subtypes. Finally, there is no possibility of finding one efficient cure for all, or even the majority of CMT diseases. Every subtype of CMT needs an individual approach backed up by its own research field. Thus, it is little surprise that our knowledge of CMT disease as a whole is selective and therapeutic approaches are limited. There is an urgent need to develop new CMT models to fill the gaps. In this review, we discuss the advantages and disadvantages of y...
ObjectiveTo test the hypothesis that monogenic neuropathies such as Charcot-Marie-Tooth disease (... more ObjectiveTo test the hypothesis that monogenic neuropathies such as Charcot-Marie-Tooth disease (CMT) contribute to frequent but often unexplained neuropathies in the elderly, we performed genetic analysis of 230 patients with unexplained axonal neuropathies and disease onset ≥35 years.MethodsWe recruited patients, collected clinical data, and conducted whole-exome sequencing (WES; n = 126) and MME single-gene sequencing (n = 104). We further queried WES repositories for MME variants and measured blood levels of the MME-encoded protein neprilysin.ResultsIn the WES cohort, the overall detection rate for assumed disease-causing variants in genes for CMT or other conditions associated with neuropathies was 18.3% (familial cases 26.4%, apparently sporadic cases 12.3%). MME was most frequently involved and accounted for 34.8% of genetically solved cases. The relevance of MME for late-onset neuropathies was further supported by detection of a comparable proportion of cases in an independe...
The question of whether a newly identified sequence variant is truly a causative mutation is a ce... more The question of whether a newly identified sequence variant is truly a causative mutation is a central problem of modern clinical genetics. In the current era of massive sequencing, there is an urgent need to develop new tools for assessing the pathogenic effect of new sequence variants. In Charcot-Marie-Tooth disorders (CMT) with their extreme genetic heterogeneity and relatively homogenous clinical presentation, addressing the pathogenic effect of rare sequence variants within 80 CMT genes is extremely challenging. The presence of multiple rare sequence variants within a single CMT-affected patient makes selection for the strongest one, the truly causative mutation, a challenging issue. In the present study we propose a new yeast-based model to evaluate the pathogenic effect of rare sequence variants found within the one of the CMT-associated genes, GDAP1. In our approach, the wild-type and pathogenic variants of human GDAP1 gene were expressed in yeast. Then, a growth rate and mi...
Polineuropatie genetycznie uwarunkowane (HMSN, ang. hereditary motor and sensory neuropathies) zw... more Polineuropatie genetycznie uwarunkowane (HMSN, ang. hereditary motor and sensory neuropathies) zwane również chorobami kręgu Charcot-Marie-Tooth (CMT) stanowią niezwykle heterogenną genetycznie (ponad 80 genów) grupę chorób obwodowego układu nerwowego człowieka. Istotą chorób kręgu CMT jest powolnie postępujący zanik mięśni dystalnych kończyn dolnych (podudzia) i górnych (przedramiona). Jak dotąd nie opracowano skutecznej metody leczenia CMT. W pracy przedstawiono obecny stan wiedzy dotyczący kliniki, patogenezy molekularnej i pierwszych prób terapeutycznych w CMT. Omówiono również możliwości wynikające z zastosowania modelu drożdżowego w poszukiwaniach nowych substancji leczniczych, jak i identyfikacji substancji neurotoksycznych.
To date, only two splice-site mutations within the TPM2 gene have been shown to be causative for ... more To date, only two splice-site mutations within the TPM2 gene have been shown to be causative for congenital myopathies. While the majority of TPM2 gene mutations are causative for nemaline myopathy, cap disease or distal arthrogryposis, some mutations in this gene have been found to be associated with non-specific congenital myopathy. We report on a patient with such an unspecified congenital myopathy associated with distinctive facial dysmorphic features and distal arthrogryposis. Using the whole exome sequencing (WES) approach we were able to identify a novel heterozygous splice-site mutation within the TPM2 gene, showing the utility of WES in molecular diagnostics of congenital myopathies without recognizable morphological hallmarks.
THE AIM was focused on molecular analysis of the selected genes associated with autosomal recessi... more THE AIM was focused on molecular analysis of the selected genes associated with autosomal recessive Charcot-Marie-Tooth neuropathies (AR-CMT) and construction of a molecular diagnostic algorithm in this group of disorders in the Polish population. Material and methods: We analyzed a group of 138 subjects from 62 families with probably autosomal recessive inheritance and the control group of 52 individuals. The studies covered molecular genetic analysis of PMP22 gene dosage (real-time polymerase chain reaction and polymerase chain reaction restriction fragments length polymorphisms), analysis of coding regions of the GDAP1, PRX, EGR2 and CTDP1 genes using: mutation screening (single strand conformation polymorphism and heteroduplex analysis), sequencing and bioinformatics approach to the gene sequence variants. Results: Thirty sequence variants have been found in the analysed genes, 5 pathogenic mutations in the GDAP1 gene and 2 pathogenic mutations in the PRX gene. On the basis of bioinformatic analysis other nucleotide changes have been categorized as harmless polymorphisms and variants of unknown pathogenic effect. Conclusions: This is the first study focused on the autosomal recessive Charcot-Marie-Tooth disease in the Polish population. Our results show the difficulties in the interpretation of the pathogenic effect of the sequence variants (pathogenic mutation or polymorphism) which is essential for molecular diagnostics in CMT disease.
Charcot–Marie–Tooth disorders (CMT) represent a highly heterogeneous group of diseases of the per... more Charcot–Marie–Tooth disorders (CMT) represent a highly heterogeneous group of diseases of the peripheral nervous system in which more than 100 genes are involved. In some CMT patients, a few weak sequence variants toward other CMT genes are detected instead of one leading CMT mutation. Thus, the presence of a few variants in different CMT-associated genes raises the question concerning the pathogenic status of one of them. In this study, we aimed to analyze the pathogenic effect of c.664G>A, p.Glu222Lys variant in the GDAP1 gene, whose mutations are known to be causative for CMT type 4A (CMT4A). Due to low penetrance and a rare occurrence limited to five patients from two Polish families affected by the CMT phenotype, there is doubt as to whether we are dealing with real pathogenic mutation. Thus, we aimed to study the pathogenic effect of the c.664G>A, p.Glu222Lys variant in its natural environment, i.e., the neuronal SH-SY5Y cell line. Additionally, we have checked the patho...
Charcot-Marie-Tooth disease (CMT) is a heritable neurodegenerative disease that displays great ge... more Charcot-Marie-Tooth disease (CMT) is a heritable neurodegenerative disease that displays great genetic heterogeneity. The genes and mutations that underlie this heterogeneity have been extensively characterized by molecular genetics. However, the molecular pathogenesis of the vast majority of CMT subtypes remains terra incognita. Any attempts to perform experimental therapy for CMT disease are limited by a lack of understanding of the pathogenesis at a molecular level. In this study, we aim to identify the molecular pathways that are disturbed by mutations in the gene encoding GDAP1 using both yeast and human cell, based models of CMT-GDAP1 disease. We found that some mutations in GDAP1 led to a reduced expression of the GDAP1 protein and resulted in a selective disruption of the Golgi apparatus. These structural alterations are accompanied by functional disturbances within the Golgi. We screened over 1500 drugs that are available on the market using our yeast-based CMT-GDAP1 model....
Charcot–Marie–Tooth (CMT) disease encompasses a group of rare disorders that are characterized by... more Charcot–Marie–Tooth (CMT) disease encompasses a group of rare disorders that are characterized by similar clinical manifestations and a high genetic heterogeneity. Such excessive diversity presents many problems. Firstly, it makes a proper genetic diagnosis much more difficult and, even when using the most advanced tools, does not guarantee that the cause of the disease will be revealed. Secondly, the molecular mechanisms underlying the observed symptoms are extremely diverse and are probably different for most of the disease subtypes. Finally, there is no possibility of finding one efficient cure for all, or even the majority of CMT diseases. Every subtype of CMT needs an individual approach backed up by its own research field. Thus, it is little surprise that our knowledge of CMT disease as a whole is selective and therapeutic approaches are limited. There is an urgent need to develop new CMT models to fill the gaps. In this review, we discuss the advantages and disadvantages of y...
ObjectiveTo test the hypothesis that monogenic neuropathies such as Charcot-Marie-Tooth disease (... more ObjectiveTo test the hypothesis that monogenic neuropathies such as Charcot-Marie-Tooth disease (CMT) contribute to frequent but often unexplained neuropathies in the elderly, we performed genetic analysis of 230 patients with unexplained axonal neuropathies and disease onset ≥35 years.MethodsWe recruited patients, collected clinical data, and conducted whole-exome sequencing (WES; n = 126) and MME single-gene sequencing (n = 104). We further queried WES repositories for MME variants and measured blood levels of the MME-encoded protein neprilysin.ResultsIn the WES cohort, the overall detection rate for assumed disease-causing variants in genes for CMT or other conditions associated with neuropathies was 18.3% (familial cases 26.4%, apparently sporadic cases 12.3%). MME was most frequently involved and accounted for 34.8% of genetically solved cases. The relevance of MME for late-onset neuropathies was further supported by detection of a comparable proportion of cases in an independe...
The question of whether a newly identified sequence variant is truly a causative mutation is a ce... more The question of whether a newly identified sequence variant is truly a causative mutation is a central problem of modern clinical genetics. In the current era of massive sequencing, there is an urgent need to develop new tools for assessing the pathogenic effect of new sequence variants. In Charcot-Marie-Tooth disorders (CMT) with their extreme genetic heterogeneity and relatively homogenous clinical presentation, addressing the pathogenic effect of rare sequence variants within 80 CMT genes is extremely challenging. The presence of multiple rare sequence variants within a single CMT-affected patient makes selection for the strongest one, the truly causative mutation, a challenging issue. In the present study we propose a new yeast-based model to evaluate the pathogenic effect of rare sequence variants found within the one of the CMT-associated genes, GDAP1. In our approach, the wild-type and pathogenic variants of human GDAP1 gene were expressed in yeast. Then, a growth rate and mi...
Polineuropatie genetycznie uwarunkowane (HMSN, ang. hereditary motor and sensory neuropathies) zw... more Polineuropatie genetycznie uwarunkowane (HMSN, ang. hereditary motor and sensory neuropathies) zwane również chorobami kręgu Charcot-Marie-Tooth (CMT) stanowią niezwykle heterogenną genetycznie (ponad 80 genów) grupę chorób obwodowego układu nerwowego człowieka. Istotą chorób kręgu CMT jest powolnie postępujący zanik mięśni dystalnych kończyn dolnych (podudzia) i górnych (przedramiona). Jak dotąd nie opracowano skutecznej metody leczenia CMT. W pracy przedstawiono obecny stan wiedzy dotyczący kliniki, patogenezy molekularnej i pierwszych prób terapeutycznych w CMT. Omówiono również możliwości wynikające z zastosowania modelu drożdżowego w poszukiwaniach nowych substancji leczniczych, jak i identyfikacji substancji neurotoksycznych.
To date, only two splice-site mutations within the TPM2 gene have been shown to be causative for ... more To date, only two splice-site mutations within the TPM2 gene have been shown to be causative for congenital myopathies. While the majority of TPM2 gene mutations are causative for nemaline myopathy, cap disease or distal arthrogryposis, some mutations in this gene have been found to be associated with non-specific congenital myopathy. We report on a patient with such an unspecified congenital myopathy associated with distinctive facial dysmorphic features and distal arthrogryposis. Using the whole exome sequencing (WES) approach we were able to identify a novel heterozygous splice-site mutation within the TPM2 gene, showing the utility of WES in molecular diagnostics of congenital myopathies without recognizable morphological hallmarks.
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Papers by Dagmara Kabzinska