Epilepsy is a heterogeneous disease with a broad phenotypic spectrum and diverse genotypes. A significant proportion of epilepsies has a genetic aetiology. In our study, a custom designed gene panel ...with 112 genes known to be associated with epilepsies was used. In total, one hundred and fifty-one patients were tested (86 males / 65 females).
In our cohort, the highest probability for the identification of the cause of the disease was for patients with a seizure onset within the first four weeks of life (61.9% clarification rate) - about two times more than other groups. The level of statistical significance was determined using a chi-square analysis. From 112 genes included in the panel, suspicious and rare variants were found in 53 genes (47.3%). Among the 151 probands included in the study we identified pathogenic variants in 39 patients (25.8%), likely pathogenic variants in three patients (2%), variants of uncertain significance in 40 patients (26.5%) and likely benign variants in 69 patients (45.7%).
Our report shows the utility of diagnostic genetic testing of severe childhood epilepsies in a large cohort of patients with a diagnostic rate of 25.8%. A gene panel can be considered as a method of choice for the detection of pathogenic variants within patients with unknown origin of early onset severe epilepsy.
Highlights • This is the second paper describing GNB4 mutations as a cause of CMT. • De novo variant in the GNB4 gene is very likely the cause of Charcot-Marie-Tooth in a Czech patient. • The variant ...p.Lys57Glu (NM_021629.3:c.169A>G) is evaluated as pathogenic according to the recommendations of ACMG1.
Hereditary motor and sensory neuropathy-type Lom (HMSNL), also known as CMT4D, a demyelinating neuropathy with late-onset deafness is an autosomal recessive disorder threatening Roma population ...worldwide. The clinical phenotype was reported in several case reports before the gene discovery. HMSNL is caused by a homozygous founder mutation p.Arg148* in the N-Myc downstream-regulated gene 1. Here, we report findings from the Czech Republic, where HMSNL was found in 12 Czech patients from eight families. In these 12 patients, 11 of the causes were due to p.Arg148* mutation inherited from both parents by the autosomal recessive mechanism. But in one case, the recessive mutation was inherited only from one parent (father) and unmasked owing to an uniparental isodisomy of the entire chromosome eight. The inherited peripheral neuropathy owing to an isodisomy of the whole chromosome pointed to an interesting, less frequent possibility of recessive disease and complications with genetic counseling.
Neurodegenerative diseases of childhood present with progressive decline in cognitive, social, and motor function and are frequently associated with seizures in different stages of the disease. Here ...we report a patient with severe progressive neurodegeneration with drug-resistant epilepsy of unknown etiology from the age of 2 years.
Using whole exome sequencing, we found heterozygous missense de novo variant c.628G > A (p.Glu210Lys) in the
gene. This variant was recently described as de novo in 11 patients with similar neurodegeneration characterized by developmental decline initially confined to motor development followed by language regression, appearance of an extrapyramidal movement disorder, and leading to severe intellectual disability. In 3 of the 11 patients described so far, seizures were also present.
Our report expands the complex phenotype of neurodegeneration associated with the c.628G > A variant in the
gene and helps to clarify the relation between this one single recurrent pathogenic variant described in this gene to date and its phenotype. The
gene should be considered a novel candidate gene in neurodegeneration with or without epilepsy.
Inherited peripheral neuropathies (IPN) are the most common inherited neurological condition. It represents a highly heterogeneous group, both clinically and genetically. Targeted disease specific ...gene panel massively parallel sequencing (MPS) seems to be a useful tool in diagnosis of disorders with high genetic heterogeneity.
In our study, we have designed, validated and updated our own custom gene panel of all known genes associated with IPN. One hundred and ninety-eight patients have been tested so far. Only patients in whom mutations in more common causes or relevant genes have already been excluded were enrolled. Five consecutive panel designs were prepared according to recent literature search, the last one covering ninety-three genes. Each patient was tested only once. All data were evaluated with at least two different pipelines.
In summary, causative mutation has been found in fifty-one patients (26 %). The results were inconclusive in thirty-one (16 %) patients. No variants of likely significance to IPN were found in one hundred and sixteen (58 %) patients.
MPS gene panel enables testing of all known IPN causes at once with high coverage and at an affordable cost making it truly a method of choice also in IPN. Gene panel testing results in several interesting results and findings.
We detected a somatic mutation in the HLA‐B gene in a Czech hematooncological patient. We followed the development of this somatic mutation during the transition from severe aplastic anaemia through ...to myelodysplastic syndrome to acute myeloid leukaemia until haploidentical related transplantation. The somatic mutation differs from HLA‐B*14:02 in exon 3 resulting in an exchange from cysteine to serine at position 101 of the mature protein. Homology modelling of mutated S101 in HLA‐B*14 indicated possible conformational changes, which might also result in an aberrant expression. The assumption is that somatic mutation arose as a possible result of a selection mediated by a protective immune response against leukaemia.
Abstract Objectives To evaluate the contribution of eight small NSHL-AR (non-syndromic deafness, autosomal recessive) genes to hereditary hearing loss in Czech patients. Patients and methods: ...Unrelated Czech patients, adults and children, diagnosed with pre-lingual hereditary hearing loss with at least one similarly affected deaf sibling and with previously excluded mutations in the GJB2 gene were investigated by Sanger sequencing of the selected eight small NSHL-AR associated genes (CABP2 -51 patients, CIB2 - 45 patients, PJVK/DFNB59 - 53 patients, GJB3 - 46 patients, ILDR1 - 48 patients, LHFPL5 - 66 patients, LRTOMT - 60 patients, TMIE - 64 patients). Results Mutations were detected in the LHFPL-5 (DFNB67) gene. The patient is heterozygote for two already described pathogenic variants (p.Tyr127Cys, p.Thr165Met). In five samples, five rare heterozygous variants (two novel) predicted as pathogenic were detected in genes CABP2, ILDR1, LHFPL5 and LRTOMT. Conclusion Mutations in eight small NSHL-AR genes are not a frequent cause of hereditary hearing loss in the Czech Republic. This diagnostic approach permitted clarification of HL in only one patient - two heterozygous mutations were detected in LHFPL5 gene for the first time in Central Europe. As the use of panel base MPS certainly improves the diagnostic yield, future studies should rather profit from that diagnostic strategy.
Variants in the human X-linked cyclin-dependent kinase-like 5 (CDKL5) gene have been reported as being etiologically associated with early infantile epileptic encephalopathy type 2 (EIEE2). We report ...on two patients, a boy and a girl, with EIEE2 that present with early onset epilepsy, hypotonia, severe intellectual disability, and poor eye contact.
Massively parallel sequencing (MPS) of a custom-designed gene panel for epilepsy and epileptic encephalopathy containing 112 epilepsy-related genes was performed. Sanger sequencing was used to confirm the novel variants. For confirmation of the functional consequence of an intronic CDKL5 variant in patient 2, an RNA study was done.
DNA sequencing revealed de novo variants in CDKL5, a c.2578C>T (p. Gln860*) present in a hemizygous state in a 3-year-old boy, and a potential splice site variant c.463+5G>A in heterozygous state in a 5-year-old girl. Multiple in silico splicing algorithms predicted a highly reduced splice site score for c.463+5G>A. A subsequent mRNA study confirmed an aberrant shorter transcript lacking exon 7.
Our data confirmed that variants in the CDKL5 are associated with EIEE2. There is credible evidence that the novel identified variants are pathogenic and, therefore, are likely the cause of the disease in the presented patients. In one of the patients a stop codon variant is predicted to produce a truncated protein, and in the other patient an intronic variant results in aberrant splicing.
The axonal type of Charcot‑Marie‑Tooth (CMT) disorders is genetically heterogeneous, therefore the causal mutation is unlikely to be observed, even in clinically well characterized patients. ...Mitofusin‑2 (MFN2) gene mutations are the most frequent cause of axonal CMT disorders in a number of populations. There are two phenotypes; early onset, which is severe and late onset, which is a milder phenotype. A cohort of 139 unrelated Czech patients with axonal neuropathy was selected for sequencing and multiplex ligation-dependent probe amplification analysis (MLPA) testing of the MFN2 gene. A total of 11 MFN2 mutations were detected, with eight pathogenic mutations and three potentially rare benign polymorphisms. MLPA testing in 64 unrelated patients did not detect any exon duplication or deletion. The frequency of the pathogenic mutations detected in Czech hereditary motor and sensory neuropathy type II (HMSN II) patients was 7.2%. Early onset was more frequent among pathogenic mutation cases. Therefore we propose to examine the MFN2 gene mainly in patients with early and severe axonal CMT.
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