Сomprehensive chromosomal pathology diagnostic of derivative of the 4 chromosome and the small supernumerary marker chromosome

Cytogenetic diagnosis performed only by GTG-staining does not provide sufficient reliability and accuracy in the identification of structurally rearranged chromosomes. To describe the karyotype in such cases, it is required to involve methods of molecular-cytogenetic analysis. The purpose of this study was to develop methods for testing, specification and correcting the results of primary cytogenetic diagnostics using complex methods of modern chromosomal analysis by two cases of patients with abnormal karyotypes. Separation and cultivation human peripheral blood lymphocytes, metaphase chromosome preparation, GTG-, CBG-, Ag-NOR-differential staining of chromosomes, chromosomal in situ suppression hybridization were done according to standard protocol. The creation of microdissection DNA probes and their quality control were performed as described previously. Chromosomes were counterstained with DAPI to visualize DNA after in situ hybridization. Inverted DAPI banding of chromosomes was used for chromosome identification, according to ISCN (2009). Using the GTG-, CBG-, Ag-NOR-staining of chromosomes, chromosomal in situ suppression hybridization with specially prepared microdissection DNA probes, the patient’s karyotype, previously described as 46,XX,der(4)t(4;?)(p12;?) or del(4)(p12p15.2), was determined as 46,XX,del(4)(p12p15.2), and the patient’s karyotype previously described as 47,XY,+22 was determined as 47,XY,+invdup(15)(q13). Applying methods of cytogenetic analysis, including methods of differential staining of chromosomes and fluorescent in situ hybridization with specially prepared DNA probes, allows to specify and, if necessary, to correct the description of the karyotype, resulting in accurate and reliable description of patient karyotypes. Clarification of the cytogenetic diagnosis is important for the medical-genetic predictions.

хромосомы, кариотип, цитогенетическое исследование, микродиссекция метафазных хромосом, флуоресцентная гибридизация in situ, медико-генетический прогноз, chromosomes, karyotype, cytogenetic tests, microdissection of metaphase chromosomes, fluorescence in situ hybridization, medico-genetic predictions

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