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Chromosomal investigation in foetuses with developmental abnormalities
Štolfa, Miroslav ; Novotná, Drahuše (advisor) ; Král, Jiří (referee)
Chromosomal aberrations are common causes of abnormal development of fetuses leading to the birth of malformed indvidual or to the intrauterine death. Half of miscarriages in the first trimester and a third in the second trimester are caused by fetal chromosomal abnormalities, mainly aneuploidies. If fetus is abnormally developed, invasive prenatal cytogenetic diagnosis should be recommended. Positive cytogenetic finding can be reason for induced abortion till the end of 24th week of gestation. We investigated 81 miscarriages, 46 fetuses from induced abortions and 80 fetuses with abnormal development from ongoing pregnancies. G-banding analysis was used as the main method for investigating miscarriages. Genomic DNA isolated from abnormally developed fetuses was screened by array CGH technique. We found 43,75 % chromosomal abnormal miscarried fetuses, majority of them with numerical aberrations (91,4 %). In group of induced abortions, 25,71 % fetuses carried chromosomal abnormality. The lowest rate 11,67 % of chromosoal aberrations was detected in group of prenatally diagnosed fetuses from ongoing pregnancies. Array CGH detected submicroscopic aberrations in 13,41 % fetuses with ultrasound findings. All together 25,74 % microscopic and causal submicroscopic chromosomal abnormalities were found to be...
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Detection of submicroscopic chromosomal aberrations in phenotypically abnormal carriers of apparently balanced rearrangements using array CGH
Slámová, Zuzana ; Sedláček, Zdeněk (advisor) ; Michalová, Kyra (referee) ; Kuglík, Petr (referee)
Carriers of apparently balanced chromosomal aberrations (BCA) are usually phenotypically normal. However, it has been estimated that up to 27% of these BCA may be associated with an abnormal phenotype, most often caused by cryptic imbalances at the breakpoints, gene disruption by the breakpoint or via the position effect. In contrast to conventional karyotyping, molecular cytogenetic techniques enable more detailed BCA characterization and better correlation between genotype and phenotype of the patient. The aim of this thesis was to evaluate the presence of copy number variants (CNVs) at breakpoints or elsewhere in the genome in patients with abnormal phenotype who carry de novo or inherited BCA. 54 BCA were investigated using array CGH (20 de novo cases, 27 inherited and 7 cases of unknown origin) including 32 reciprocal translocations, 6 robertsonian translocations, 12 inversions and 4 complex chromosomal rearrangements. If possible, the parents were also examined to ascertain the inheritance of the relevant CNVs. In order to specify microarray findings or exclude gene disruption, FISH was used in selected patients. Among the patients included, in 31,5% (17/54) at least one (in 8 patients more than one) significant CNV was detected. Four cases carried cryptic imbalances only at the breakpoints,...
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Analysis of mosaic chromosomal aberrations using various methods
Oroszová, Karin ; Drábová, Jana (advisor) ; Šolc, Roman (referee)
Mosaicism is represented by two or more chromosomally different cell lines in an individual. Mosaics are most often caused by chromosome malsegregation during mitosis, resulting in the gain or loss of chromosomes, known as aneuploidy, but structural aberrations can also occur in mosaic form. The problem is the limitation of detection with standart cytogenetic methods. The present study was carried out to compare the efficiency of FISH, array CGH and cytogenetic techniques in detection of mosaicism. In the practical part the results of 45 patients with mosaicisms of aneuplody of gonosomes (26 patients) and mosaicisms of autosomes (19 patients) were compared. The data show that we have different peripheral blood karyotype and FISH results in 23 of 37 patients (62%). There was a case of failure of detection of the mosaicism on the karyotype and the FISH method revealed a abnormal cell lines with a percentage of less than 5%. The array CGH method confirmed the karyotype and FISH results in 10 out of 12 patients (83%) in peripheral blood tests. The work also dealt with artificially made mosaics. From the results, it is obvious that the FISH method has a more accurate percentage of mosaic capture compared to the karyotype. The results indicate that using the techniques in parallel allow in clinical...
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Detection of submicroscopics aberrations using arrayCGH
HORÁKOVÁ, Pavla
This thesis addresses array CGH method (Comparative Genomic Hybridization on microarrays) and its use inprenatal and postnatal genetic diagnosis. The method used was to determine the chromosomal areas in which the number of copies of DNA sequences had changed. Localizations of the aberrations sites are not known in advance; the issue is that of all genomic screening. The method is used in suspected cases of microdeletion and microduplication syndromes. It may also be used in cases of patients with pathological phenotypic changes, but other methods have shown no change in genetic makeup. This thesis focuses on diagnosis in the prenatal period and investigates the causes of pathological symptoms in the postnatal diagnosis. Firstly, this thesis describes procedures in clinical cytogenetics and then it discusses submicroscopic changes. Secondly, the thesis looks into the array CGH method, explains its procedure and use, and evaluates and interpretates its results. Finally, the work statistically evaluates the array CGH data procured in the OLG department in Thomayrova hospital from 8/ 8 to 3/19. The array CGH method may be used to supplement routinely administered cytogenetic tests. It enables specialists to obtain more detailed information about the genetic material of an individual and examine the frequency of microdeletion and microduplication syndromes. The diagnosis and prognosis of patients may be determined based on the results.
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Application of cytogenetic and molecular cytogenetic methods in prenatal diagnosis
Rašpličková, Tereza ; Novotná, Drahuše (advisor) ; Zemanová, Zuzana (referee)
Foetal anomalies found on ultrasound increase the probability of occurrence of chromosomal abnormalities. They cause about one quarter of all abortions and stillbirths and many of inborn defects in newborns. Karyotype analysis is number one method in prenatal diagnosis whereas array CGH is often used as a verification and supplemental method. The aim of this work was to prove that array CGH gives additional chromosomal findings to karyotypes and could substitute conventional karyotyping as a primary examination method in foetuses with ultrasound findings. We examined 45 prenatal samples using both methods. These samples were referred for invasive examination because of abnormal ultrasound findings. Karyotype analyses found two abnormalities in two (4,4 %) patients and array CGH identified aberrations in five (11,1 %) foetuses whereas both anomalies detected by karyotypes were discovered by array CGH too. This means that array CGH identified about 6,7 % more aberrations than karyotype. Our results correspond with scientific articles which refer that array CGH should replace karyotype not only in postnatal examinations but even in prenatal diagnosis. Keywords: chromosomal aberrations, array CGH, karyotype, prenatal diagnosis, ultrasound
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Chromosomal investigation in foetuses with developmental abnormalities
Štolfa, Miroslav ; Novotná, Drahuše (advisor) ; Král, Jiří (referee)
Chromosomal aberrations are common causes of abnormal development of fetuses leading to the birth of malformed indvidual or to the intrauterine death. Half of miscarriages in the first trimester and a third in the second trimester are caused by fetal chromosomal abnormalities, mainly aneuploidies. If fetus is abnormally developed, invasive prenatal cytogenetic diagnosis should be recommended. Positive cytogenetic finding can be reason for induced abortion till the end of 24th week of gestation. We investigated 81 miscarriages, 46 fetuses from induced abortions and 80 fetuses with abnormal development from ongoing pregnancies. G-banding analysis was used as the main method for investigating miscarriages. Genomic DNA isolated from abnormally developed fetuses was screened by array CGH technique. We found 43,75 % chromosomal abnormal miscarried fetuses, majority of them with numerical aberrations (91,4 %). In group of induced abortions, 25,71 % fetuses carried chromosomal abnormality. The lowest rate 11,67 % of chromosoal aberrations was detected in group of prenatally diagnosed fetuses from ongoing pregnancies. Array CGH detected submicroscopic aberrations in 13,41 % fetuses with ultrasound findings. All together 25,74 % microscopic and causal submicroscopic chromosomal abnormalities were found to be...
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Molecular cytogenetic analysis of mosaic chromosomal abnormalities
Cinkajzlová, Anna ; Kočárek, Eduard (advisor) ; Král, Jiří (referee)
The focus of this diploma thesis is on mosaic numerical and structural chromosomal aberrations. In its theoretical part, general problems of mosaicism, its phenotypic effect, mechanisms of origin, related epigenetic modifications, and diagnostic options are described. The methodical part of the thesis then primarily refers to fluorescence in situ hybridization (FISH) and its application in the diagnostics of mosaicism. This method was used in the examination of 29 patients with numerical as well as structural abnormalities of autosomes or gonosomes with proven or suspected mosaicism. On the basis of this analysis, possible errors of measurement were determined and data for statistic evaluation were retrieved. For the examinations of three patients an alternative of the comparative genomic hybridization, the array CGH technique, was applied. The FISH method, although being based on random selection and human factor, proved sufficient sensitivity as well as specificity in the field of low-frequency mosaicism diagnostics. The main critical factors responsible for potential misinterpretation of the data arose from inherent characteristics of the biological material, incorrect targeting of the analysis, probe instability, bleed through effect and absence of mitosis during the structural aberrations analysis.
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Using MLPA method for determining unbalanced changes in genome
KŘÍHOVÁ, Miroslava
Unbalanced chromosomal structural changes are connected with the presence of supernumerary particular part of chromosome, or the chromosome is absenting. MLPA is a method based on PCR principal, which amplifies MLPA probes, not the target sequences. MLPA probes hybridize to target sequences and then ligate them. Only one pair of primers is used. In the theoretical part the MLPA method is presented. Additionally, other diagnostics method of clinical genetic are mentioned (for example PCR, FISH, Array CGH). Diseases caused by unbalanced chromosomal structural changes are disscused too. Mental retardation and BRCA 1, 2 mutation were the main topic. The experimental part took place in Molecular Biology and Genetics Laboratory in the hospital in České Budějovice. I did my experiments under professional care of Mgr. Ondřej Scheinost and his colleagues. The aim of using MLPA method was to diagnose BRCA 1, 2 gene, microdeletion syndroms or subtelomeric deletions. All procedures were done according to standards. The final part of my thesis is concerned on the results interpretation and their comparation with other methods. I also thought over different approach of statistical analysis in MLPA.
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