ABSTRACT
Introduction: Cytogenetics is the area of genetics that studies chromosomes, including numerical changes, and their relationship to structural imbalances. Among the classical cytogenetics tests, the GTG banding karyotype is the most widely used. The period of culture establishment is a critical step, which can affect the pre-analytical phase of the test. Objective: To evaluate, at different establishment times, culture viability and banding resolution. Material and methods: Collection of 10 ml blood from 10 subjects was carried out for culture analysis. For viability analysis, mitotic index (MI) and banding resolution were assessed. Results: The comparative analysis of MI showed significant difference between times. In the assessment of banding resolution, the mean value of the bands was higher at times zero and 24 hour. Discussion: The MI reflects inhibition of cell cycle progression and/or loss of ability to proliferate. When the pair analysis was performed, a difference between zero and 48 hours was observed. The average number of bands analyzed at times zero and 24 hours did not indicate difference in the quantity and quality of the bands when cultures were grown immediately after blood collection or within 24 hours. At the 48th hour after blood collection significant reduction of band resolution was observed. Conclusion: These data highlight the importance of the biological material quality, as viability is lower when the culture is grown after 24 hours, as well as the banding resolution...
Introdução: Citogenética é a área da genética que estuda os cromossomos, incluindo alterações numéricas, estruturais e sua relação com distúrbios. Nos exames de citogenética clássica, o cariótipo com bandamento GTG é a metodologia mais utilizada, sendo o período de implantação da cultura uma fase crítica, que pode comprometer a fase pré-analítica do exame. Objetivo: Avaliar, em diferentes tempos de implantação, a viabilidade das culturas e o número de bandas. Material e métodos: Foram colhidos 10 ml de sangue de 10 sujeitos para realização das culturas. Para análise da viabilidade, foram utilizados o índice mitótico (IM) e a análise de resolução por bandamento. Resultados: A comparação dos valores do IM demonstrou desigualdade entre os diferentes tempos analisados. Na análise de resolução, o valor médio das bandas foi maior nos tempos zero e 24 horas. Discussão: O IM reflete a inibição da progressão do ciclo celular e/ou a perda da capacidade de proliferação. Quando o IM foi comparado dois a dois, verificou-se a diferença entre os tempos zero e 48 horas. O número médio de bandas analisadas nos tempos de zero e 24 horas mostrou que não houve diferença na quantidade e na qualidade das bandas quando as culturas foram implantadas logo após a coleta do sangue ou em até 24 horas. No tempo de 48 horas, houve significativa redução da resolução. Conclusão: Os dados obtidos reforçam a importância da qualidade do material biológico, visto que a viabilidade decai quando a implantação da cultura é realizada após 24 horas, assim como a resolução das bandas...
Subject(s)
Humans , Male , Female , Adult , Cytogenetic Analysis/methods , Mitotic Index/methods , Karyotyping , Time FactorsABSTRACT
Chromosomal abnormalities are thought to be the most common cause of mental retardation (MR). However, apart from a few selected types with typical aneuploidy, like Downs syndrome, Klinefelter syndrome, Turner syndrome, etc., the frequency of detectable chromosomal abnormalities in association with idiopathic MR is very low. In this study, we have investigated chromosomal abnormalities in female MR subjects (n = 150) by high-resolution GTG banding. Of them, 30 cases were diagnosed as Downs syndrome. Among the remaining (n = 120), chromosomal abnormalities/marked polymorphisms were detectable in only three MR cases (0.025).
Subject(s)
Chromosome Aberrations/epidemiology , Chromosome Aberrations/genetics , Chromosome Banding/methods , Down Syndrome/diagnosis , Female , Humans , Intellectual Disability/etiology , Intellectual Disability/genetics , Karyotype , Polymorphism, GeneticABSTRACT
Background: An abnormal karyotype in either partner, especially featuring a translocation and/or inversion is considered to be a cause of recurrent miscarriages. It is generally assumed that recurrent miscarriage might be due to recurrent chromosomal abnormalities in the fetus due to a balanced aberration in one of the parents being inherited by the offspring in an unbalanced form. Aim: Evaluation of chromosomal rearrangements in couples with recurrent miscarriages. Materials and Methods: Peripheral blood was collected and lymphocyte cultures were set up. Slides prepared from the cell suspension were stained and screened for metaphases followed by karyotyping. Result: Balanced translocation was observed in the male partner in one case and in the female partners in the three other cases. Conclusion: Couples with recurrent miscarriage should be investigated for chromosomal rearrangements, thus helping in genetic counseling and providing the options for future pregnancies.
ABSTRACT
BACKGROUND : Cytogenetics study using cultured T-lymphocytes derived from peripheral blood is the easiest way to study human chromosome complement and it is also an excellent method to study chromosomal abnormalities: either structural or numerical. The structural chromosomal abnormalities include translocations, deletions, duplications, ring chromosomes and isochromosomes. AIMS : Cases presenting with multiple congenital anomalies, mental retardation, pregnancy wastage or abnormalities in sexual function are referred to the Division of Human Genetics to rule out chromosomal anomalies. METHODS AND MATERIALS : A total of 70 cases with multiple congenital anomalies, mental retardation, pregnancy wastage or abnormalities in sexual function were studied. About 72 h cultured peripheral lymphocytes subjected to GTG banding were analyzed to look at the chromosome profile. RESULTS : Out of 70 cases of reciprocal translocation, single cell translocations were seen in ten cases (three females; seven males). Looking at the case profile, it was seen that they were referred for mental retardation, bad obstetric history and hypogonadism. It was seen that seven cases (70%) had t(7;14), two (20%) had complex translocations: t(X;9;8) and t(2;10;11), and one (10%) had t(4;21). CONCLUSIONS : Depending on the phenotype, the patients were informed of their abnormality and the need for a look out for the development of any associated problems.
ABSTRACT
Comparative genomic hybridization (CGH) can now be applied to detect the origin of extra or missing chromosomal material in cases with common unbalanced aberrations and in prenatal investigations. This method has been used in 13 cases of fetal samples for this study; 3 for amniocytes, 2 for cord blood and 8 for abortus tissues. These samples were previously subjected to GTG-banding. Our study showed aneuploidy in 8 cases, and partial monosomy, partial trisomy or marker chromosome in the remaining 5. The CGH disclosed further small genetic imbalances in 4 of all 13 cases: a prenatal sample showing del(20)(q13) by GTG confirmed a loss of the segment 20p13-pter by CGH; a marker chromosome manifested normal CGH profile; chromosome der(?)(?;15) found in an abortus sample by GTG turned out to be a loss of 15pter-q14 (partial monosomy) and a gain of 10pter-q22 (partial trisomy); the der(15) shown by GTG represented partial trisomy of 3q24-qter. These findings show that CGH is very useful and efficient for cytogenetic investigations of clinical cases.