Chromosomal Heteromorphism with Reference to Cancer and Reproduction in Human: An Appraisal
Abstract
Background and Objectives: Human cell nucleus has, the genome consisting of euchromatin and heterochromatin. The euchromatin has gene-rich and actively functional. The heterochromatin has two components namely constitutive and facultative, where the former is highly polymorphic. It is related to numerous diseases like cancer and infertility which is now well known, though it was earlier thought to be inactive; hence the implication of these polymorphic variants of chromosomes is reviewed with respect to acrocentric and non- acrocentric types. Methodologies: The polymorphic variants can be detected by C, G, Q and R banding techniques. We usually follow G band preparation of karyotypes following World Health Organisation (WHO) manuals and their role in cancer and reproduction is reviewed. Review and Conclusion: It is emphasized that most of the p and q arms of 1, 9, 16, D and G groups and X, Y chromosomes exhibited polymorphism which are related to cancerous and infertile conditions in both sexes. Data on few non-acrocentric chromosomes like 2, 4, 8, 10, 12, 18, 19 and 20 are not available. Our review however indicated that the evaluation of specific heteromorphic variants needs to be detected using specific probes for confirmation of anomaly to assist affected cases, though earlier data indicated ambiguous information with few cases analyzed regarding assisted reproductive technologies and malignancy condition. This appraisal thus would play a key role in human chromosomal heteromorphic abnormalities and recommend genetic tests and counseling ultimately made available to the affected cases.
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Background and Objectives: Aneuploidy is one of the major concerns to cause genetic anomalies. This condition is mostly related to addition and/or deletion with respect to set(s) of chromosomes. Here, we report an analysis of 5740 referral cases during three consecutive years (2015 – 2018) from our Diagnostic Research Center, Ahmedabad for aneuploidy pattern. Methodologies: The patients were asked to fill the necessary forms and their blood (5ml) was drawn for chromosomal studies using the Karyotyping following International System for Human Cytogenetic Nomenclature (ISCN) manual. Results: The data revealed the numerical aberrations for only aneuploidy detected was (3.7%; 211/5740). In this report, constitutional (c) autosomal aneuploidy was 75% (158/211). The total mosaic cases were nine (9/211) comprising constitutive (2) and acquired (7) aneuploidy cases. In autosomal aneuploidy, cT21 was higher (96%; 152/158) than others (4%; 6/158) comparatively. Among cT21 (152), males (76%; 115/152) were more affected than females (24%; 37/152). These statistical data also revealed that acquired chromosomal aneuploidy (leukemia) possessed (25%; 53/211); with more mosaic cases (7/211). Conclusion: Couples with such conditions are eligible for genetic tests and counseling as well as new strategies are urgently to be undertaken by governmental organizations (GOs) and non-governmental organizations (NGOs) for affected families with better personalized and informed decision making. The significance of these data is thus discussed in relation to genetic disorders caused by constitutional and acquired aneuploidy of leukemic blood in this report.
Background: Heteromorphic variants including Yq12 material, being inserted or added to autosomal
chromosomes have been reported for chromosomes 1, 7, 11, 13, 14, 15, 21 and 22. Here we describe a novel
insertion of Yq12 heterochromatin into a chromosome 17; to the best of our knowledge no similar cases have been reported previously.
Methods: GTG-, C-banding, fluorescence in situ hybridization (FISH), and homemade human heterochromatin
specific multicolor FISH probes set (HCM-mix) were used to define the abnormality. A whole chromosome painting (wcp) probe for #17 together with a probe for Yq12 heterochromatin was hybridized to the patient sample. Additionally, Y microdeletion PCR was done to detect possible AZF subregional deletions.
Results: The male patient had normal sperm analysis and no AZF deletions on Y chromosome. GTG and Cbanding showed an additional band on chromosome 17q21. FISH studies revealed that the insertion was derived from Yq12 heterochromatin.
Conclusions: The heterochromatin insertion on 17q21 originating from Yq12 chromosome did not affect the
spermatogenesis of aberration carrier and is probably not the cause of infertility in these partners. However, a new heteromorphic variant was identified in this case.
A total of 440 couples (880 individuals) with history of repeated abortions were evaluated for heterochromatic variations. The present study was undertaken with the objective of investigating the role of heteromorphic variations in pregnancy losses and reproductive failures in the human population. Peripheral blood samples of the couples were cultured and processed to obtain metaphase plates. The GTG banded slides were analysed using automated karyotyping system (Cytovision) for precise analysis of the karyotype. The study revealed that the frequency of chromosomal anomalies and variations leading to Bad Obstetric History (BOH) was 17%. Chromosomal rearrangements constituted 24% of the cases while heterochromatic variations constituted 76% of the chromosomal cause for BOH. The heterochromatic variations associated with BOH included inversions and deletions. Our study revealed a correlation between BOH and heterochromatic variations of Chromosome 1 and 9.
Background and objective:
Male infertility has been associated with aneuploidies and structural chromosomal abnormalities, Yq microdeletions and specific gene mutations and/or polymorphisms. Besides genetic factors, any block in sperm delivery, endocrine disorders, testicular tumours, infectious diseases, medications, lifestyle factors and environmental toxins can also play a causative role. This study aimed to determine the constitutional karyotype in infertile males having normal female partners in a south Indian population.
Materials and methods:
A total of 180 men with a complaint of primary infertility ranging from 1 to 25 years were screened for chromosomal abnormalities through conventional analysis of GTG-banded metaphases from cultured lymphocytes.
Results:
Four individuals were diagnosed to have Klinefelter syndrome. Two cases exhibited reciprocal translocations and one showed a maternally inherited insertion. Polymorphisms were seen in sixty-seven patients (37.2%).
Conclusion:
The occurrence of chromosomal abnormalities in 4.6% and variants involving the heterochromatic regions of Y, chromosome 9 and the acrocentric chromosomes in 38.2% of the infertile men with an abnormal seminogram strongly reiterates the inclusion of routine cytogenetic testing and counselling in the diagnostic work-up prior to the use of assisted reproduction technologies.
Males with abnormal karyotypes and subgroups of fertile and infertile males with normal karyotypes may be at risk of producing unbalanced or aneuploid spermatozoa. Biological, clinical, environmental and other factors may also cause additional sperm aneuploidy. However, increased risk of sperm aneuploidy is directly related to chromosomally abnormal embryo production and hence to poor reproductive potential. This systemic literature review focuses on the identification of these males because this is an essential step in the context of assisted reproduction. This research may allow for a more personalised and, hence, more accurate estimation of the risk involved in each case, which in turn will aid genetic counselling for affected couples and help with informed decision-making.
Introduction: This paper presents a detailed study of inversion in chromosome 9 and its correlation with sub-fertility amongst 26 couples. Until now, there have been conflicting views on the clinical outcome of the pericentric inversion in chromosome 9. Many researchers consider this anomaly as a predisposing factor for infertility. Methods: In the present study, the karyotyping analysis of 500 couples was carried out to investigate the genetic basis for infertility in these subjects. Results and Conclusion: It was observed that a significant fraction (5.2%) of the total group had a pericentric inversion in chromosome 9 as the only known abnormality. The incidence of this abnormality in infertile patients was significantly higher than the reported value of 1%-3% in the normal population. Moreover, it was observed that the incidence of the inv (9) karyotype in the male patients was 2.5 times higher than that in females. These correlations clearly indicated that the inv (9) karyotype was not a normal karyotype but that it had a harmful effect on fertility.
Cytogenetic heteromorphisms are described as variations at specific chromosomal regions with no impact on phenotype. The purpose of this study was to investigate the effects of these chromosomal polymorphisms involved in reproductive failure in the Romanian population.
One thousand eight hundred and nine infertile patients, who were referred to Life Memorial Hospital, Bucharest, Romania, between January 2008 and April 2011, were investigated in this retrospective study. The frequency of chromosomal polymorphic variations was calculated for these patients. The control group is represented by 1116 fetuses investigated by amniocentesis between January 2009 and April 2011.
In this study 122 (6.74%) infertile patients and 63 fetuses (5.65%) showed chromosomal polymorphic variations. The differences between the two groups was not statistically significant (p <0.242) but there was statistical significance for some specific chromosomal polymorphisms [inv(9),1qh+, 9qh+, fra(17)].
Some chromosomal polymorphic variations appear to be associated with reproductive failure. The statistically significantly higher incidence of heterochromatic variations found in infertile individuals emphasizes the need to assess their role in infertility and subfertility.
Various studies have reported a higher incidence of heterochromatin variants among individuals with idiopathic reproductive failure. The aim of the present study was to assess the frequency of chromosomal heteromorphisms in 948 women with history of reproductive failure and 478 controls in the Prešov region (Slovakia) (1998-2013) using G-banding and C-banding cytogenetic techniques. In 95 individuals (10.02%) with reproductive failure heterochromatin variants of chromosomes 1, 9, 16 and Y were detected. In the control group, there were 15 (3.15%) heterochromatin variants. The most frequent heterochromatin variants in the reproductive failure group were heterochromatin variants within chromosome 9 (9qh+/9qh-/inv(9)). The overall incidence of heterochromatin variants in women with reproductive failure was higher than in controls (p<0.0001; 95% CI 1.971-5.996). The results of the study confirmed the higher occurrence of chromosome anomalies in Slovak women with reproductive failure that absolutely reasons indication of cytogenetic examination.