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Molecular genetic analysis of the causes of selected hereditary forms of colorectal polyposis
Florianová, Martina ; Kohoutová, Milada (advisor) ; Křepelová, Anna (referee) ; Vodičková, Ludmila (referee)
Colorectal cancer (CRC) is one of the most common cancers worldwide. Hereditary colorectal adenomatous polyposis syndromes are a predisposition to colorectal carcinoma development. The most common analyzed syndromes are familial adenomatous polyposis (FAP) that results from germline mutations in the APC gene and MUTYH - associated polyposis (MAP) caused by germline mutations in the MUTYH gene. The aim of this study was to clarify genetics causes of colorectal polyposis in a set of probands without the germline mutation in the APC gene. Within studyʼs scope the presence of large deletion in APC gene was tested, there was looked for germline mutations in MUTYH gene, alternatively germline mutations in MSH6 gene by probands with monoallelic MUTYH mutation, item there was tested an effect of detected APC variants on gene expression. Screening for large deletions was performed by multiplex ligation dependent probe amplification (MLPA). A set of 120 APC-negative probands was examined for the presence of germline MUTYH mutations by denaturing high performance liquid chromatography (dHPLC). Subsequently a set of 145 APC-negative probands was screened only for germline MUTYH mutation in exon 7 and 13 by high resolution melting (HRM) analysis. Analysis of the effect on expression was tested by ten APC...
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Human Diseases Caused by Germline Mutations of the Hedgehog Signaling Pathway
Trsová, Iva ; Křepelová, Anna (advisor) ; Vícha, Aleš (referee)
The Hedgehog signalling pathway is involved in regulation of differentiation of embryonic cells, in body patterning, in development of brain, bone, muscle, gastrointestinal tract, lungs, and in maintenance and regeneration of adult tissues. The pathway includes more than 10 proteins: receptors, coreceptors, ligands, transcription effectors and repressors, linked in complex functional interactions. Disruption of the hedgehog signalling during embryogenesis can lead to a serious developmental disorder - to holoprosencephaly. Loss-of- function mutations of PTCH1 lead to Gorlin syndrome - a hereditary predisposition to basal cell carcinoma associated with anomalies of brain, scull, vertebrae, and ribs. Both holoprosencephaly and Gorlin syndrome have been shown to be genetically heterogeneous, both can be caused by germline mutations of several genes of the Hedgehog signalling pathway. From 2006 to 2016, the PTCH1 gene was analysed for diagnostic purposes in 70 unrelated patients with suspicion of Gorlin syndrome (MIM 109400) referred to the Department of Biology and Medical Genetics, 2nd Medical School and University Hospital Motol, Prague. A pathogenic variant of the PTCH1 gene was detected in 35 (50%) of patients. No mutation was found in 35 patients, 10 of them fulfilled, and 25 of them did not...
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Human Diseases Caused by Germline Mutations of the Hedgehog Signaling Pathway
Trsová, Iva ; Křepelová, Anna (advisor) ; Vícha, Aleš (referee)
The Hedgehog signalling pathway is involved in regulation of differentiation of embryonic cells, in body patterning, in development of brain, bone, muscle, gastrointestinal tract, lungs, and in maintenance and regeneration of adult tissues. The pathway includes more than 10 proteins: receptors, coreceptors, ligands, transcription effectors and repressors, linked in complex functional interactions. Disruption of the hedgehog signalling during embryogenesis can lead to a serious developmental disorder - to holoprosencephaly. Loss-of- function mutations of PTCH1 lead to Gorlin syndrome - a hereditary predisposition to basal cell carcinoma associated with anomalies of brain, scull, vertebrae, and ribs. Both holoprosencephaly and Gorlin syndrome have been shown to be genetically heterogeneous, both can be caused by germline mutations of several genes of the Hedgehog signalling pathway. From 2006 to 2016, the PTCH1 gene was analysed for diagnostic purposes in 70 unrelated patients with suspicion of Gorlin syndrome (MIM 109400) referred to the Department of Biology and Medical Genetics, 2nd Medical School and University Hospital Motol, Prague. A pathogenic variant of the PTCH1 gene was detected in 35 (50%) of patients. No mutation was found in 35 patients, 10 of them fulfilled, and 25 of them did not...
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Spectrum of FGFR3 gene mutations in hypochondroplasia
Janoušková, Simona ; Křepelová, Anna (advisor) ; Baxová, Alice (referee)
Hypochondroplasia (MIM 146000) is a skeletal dysplasia characterized by disproportional dwarfism with rhizomelic or mesomelic shortening of the upper and lower extremities, with variable severity. Patients often have macrocephaly with normal facial features. Hypochondroplasia is a disease with autosomal dominant inheritance. In some patients it is caused by germline mutations in the FGFR3 gene, in others the cause of the disease remains unknown . The FGFR3 gene encodes a tyrosine kinase receptor. This receptor negatively regulates the conversion of cartilage to bone. FGFR3 gene mutations that cause hypochondroplasia lead to constitutive activation of the receptor and inhibit the growth of long bones. In this study, we analysed selected regions (exons) of the FGFR3 gene in 98 patients with disproportional dwarfism and clinical diagnosis of hypochondroplasia. Eighteen patients from 12 families had familial and 80 patients had sporadic form of the disease. All patients were previously tested negative for frequent germline mutations in exon 13 (codon 540) and exon 15 (codon 650). Genomic DNA was isolated from patient's peripheral blood leukocytes. The examination was conducted with the informed consent of the patient or his legal representative. We performed mutational analysis by direct sequencing of...
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Molecular genetic analysis of chromosomal region 8q24 in patients with trichorhinophalangeal syndrome or isolated exostosis
Klugerová, Michaela ; Šolc, Roman (advisor) ; Křepelová, Anna (referee)
Trichorhinophalangeal syndrome is a malformation syndrome characterized by craniofacial and skeletal abnormalities and is inherited in an autosomal dominant manner. We distinguish free subtypes on clinical and molecular level - TRPS I, TRPS II, TRPS III. All TRPS patients have sparse hair, a pear-shaped nose, a long flat philtrum, a thin upper lip and protruding ears. Skeletal abnormalities include cone-shaped epiphyses at the phalanges, hip malformations and short stature are present. The subgroups TRPS I and TRPS III are result of the mutated TRPS1 gene, which is maped into the 8q24 region. This gene is situated proximal of the EXT1 gene, both genes are affected in a subgroup of patients with TRPS II. These patients suffer more from multiple (cartilaginous) exostoses and mental retardation. In this work we performed molecular genetic analysis of a sample of 16 patients, 8 probands showed a TRPS phenotype and 8 probands had only isolated exostoses. The peripheral venous blood of patients was used to gain purified DNA, which was subsequently used to investigate the chromosome 8q24 region using MLPA ("multiplex ligation-dependent probe amplification"). This analysis revealed a deletion in 1 TRPS patient and 1 patient with exostoses. Sequencing of the TRPS1 gene coding exons in remaining 7 TRPS...
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Genetics of Craniosynostosis.
Valterová, Simona ; Křepelová, Anna (advisor) ; Baxová, Alice (referee)
Craniosynostoses are premature fusions of one or more cranial sutures. They affect all cranial sutures and are the main symptom of many genetic syndromes. Syndromes connected with craniosynostosis are serious disorders associated with skeleton abnormalities, limb malformations or mental disability. These syndroms are caused by different mutations in FGFR1, FGFR2, FGFR3, TWIST1, EFNB1, RECQL4, and RAB23 genes. The aim of this review was to summarize contemporary knowledge of phenotype and genetic basis of these diseases.
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Neurofibromatosis type 1 and NF1 germline mutations in Czech patients
Bendová, Šárka ; Křepelová, Anna (advisor) ; Kleibl, Zdeněk (referee) ; Kadlecová, Jitka (referee)
Neurofibromatosis type 1 (NF1, MIM 162200) is an autosomal dominant disorder affecting about 1 of 3000 live births, involving many cell types and organs, and associated with an increased risk of malignancy, predominantly of the central and peripheral nervous system 1. Tumour development is caused by inactivation of the NF1 tumour suppressor gene and subsequent cell cycle deregulation 2. Mutational analysis of NF1 is a challenge due to the presence of pseudogenes, large size of the gene, lack of mutational hotspots, and occurrence of a very diverse spectrum of mutations. There is no clear-cut genotype-phenotype correlation allowing accurate prediction of severity of the disorder. Only two mutations have been associated with a particular NF1 phenotype 3,4. This PhD thesis is composed of six publications dealing with NF1. Publications 1 and 6 are focused on NF1 mutation analysis in 67 patients from the Czech Republic. Genotypes and spectra of causal mutations are presented together with phenotypes of the patients and comparison of efficiency of various methods. Sporadic or familial cases with known germline mutation were distinguished by mutational analysis of other family members. This led to a hypothesis that the incidence of sporadic cases could had been overestimated in the past because of overlooked...
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The influence of variants in genes associated with carcinogenesis on predisposition to and phenotype of hereditary and sporadic tumour diseases of gastrointestinal tract
Vasovčák, Peter ; Křepelová, Anna (advisor) ; Kohoutová, Milada (referee) ; Plevová, Pavlína (referee)
This PhD. thesis deals with four different topics for which an increased risk of the development of colorectal cancer (CRC) is the common denominator. The first part is aimed to Cowden syndrome (CS), the second to Peutz-Jeghers syndrome (PJS), the third to sporadic CRCs in Czech population and the fourth is dedicated to a patient with a constitutional mismatch repair deficiency syndrome (CMMR-D) and a particular mutational profile. Cowden syndrome (CS) is an autosomal dominant disorder with a predisposition to tumours, especially breast, thyroid and uterine tumours. Pathognomonic features are mucocutaneous lesions with almost a 100% penetrance until 30 years of age (1). Despite the established diagnostic criteria (2), classification of the CS is a challenge due to extremely variable phenotypic spectra and a variable expression of the disease. Molecular-genetic analysis of the causal PTEN gene may confirm or exclude the suspicion of the CS (3). We have analysed and described two patients (Publication 1 and 2) who presented with variable expression of the disease. First one manifested with massive polyposis of the gastrointestinal tract (GIT) and the other patient developed the malignant disease. Peutz-Jeghers syndrome (PJS) is an autosomal dominant disorder characterised by the presence of mucocutaneous...
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