Karyotype patterns, clinical features, and parental ages of three predominant live born autosomal trisomies of Northeast Malaysia

Chromosomal abnormality is one of the causes of congenital disorders among newborns. Despite aneuploidy being the major cause of first trimester miscarriages, very few aneuploidies such as trisomies of chromosomes 13, 18 and 21 survive to birth. The results of 4,064 patients referred for cytogenetic analysis at Human Genome Centre, Universiti Sains Malaysia, Kelantan, Malaysia between 2008 and 2019 were reviewed. We retrospectively investigated the karyotype patterns, clinical features and parental ages of the three common live-born autosomal trisomies such as trisomy 13, trisomy 18 and trisomy 21. The relative frequency of cases with the total sample received and cultured was calculated in each group and compared with those reported elsewhere. Between 2008 and 2019, a total of 1034 live-born trisomic cases which accounted for 25.4% of the 4064 total referred cases and 73.7% of 1403 suspected trisomy cases, were identified, with age ranging from newborns to 57 years. Down syndrome was the commonest aneuploidy (857 cases; 21.1%) followed by Edwards syndrome (133 cases; 3.3%) and Patau syndrome (44 cases; 1.1%). The number of diagnosed cases for each of the trisomies was fairly stable from year to year. About two-thirds of both maternal and paternal ages were ≥ 35 years. This is the first cytogenetic report on the common live-born autosomal trisomies in the North-Eastern region of Malaysia. The prevalence of trisomies 21 was found to be higher compared to an earlier study in the North-Western region of Malaysia, wherein also, advanced maternal age was a significant risk factor.

Clinical implications of conventional cytogenetics, fluorescence in situ hybridization (FISH) and molecular testing in chronic myeloid leukaemia patients in the tyrosine kinase inhibitor era - A review

Chronic myeloid leukaemia (CML) provides an illustrative disease model for both molecular pathogenesis of cancer and rational drug therapy. Imatinib mesylate (IM), a BCR-ABL1 targeted tyrosine kinase inhibitor (TKI) drug, is the first line gold standard drug for CML treatment. Conventional cytogenetic analysis (CCA) can identify the standard and variant Philadelphia (Ph) chromosome, and any additional complex chromosome abnormalities at diagnosis as well as during treatment course. Fluorescence in situ hybridization (FISH) is especially important for cells of CML patients with inadequate or inferior quality metaphases or those with variant Ph translocations. CCA in conjunction with FISH can serve as powerful tools in all phases of CML including the diagnosis, prognosis, risk stratification and monitoring of cytogenetic responses to treatment. Molecular techniques such as reverse transcriptase-polymerase chain reaction (RT-PCR) is used for the detection of BCR-ABL1 transcripts at diagnosis whereas quantitative reverse transcriptase-polymerase chain reaction (qRTPCR) is used at the time of diagnosis as well as during TKI therapy for the quantitation of BCR-ABL1 transcripts to evaluate the molecular response and minimal residual disease (MRD). Despite the excellent treatment results obtained after the introduction of TKI drugs, especially Imatinib mesylate (IM), resistance to TKIs develops in approximately 35% - 40% of CML patients on TKI therapy. Since point mutations in BCR-ABL1 are a common cause of IM resistance, mutation analysis is important in IM resistant patients. Mutations are reliably detected by nested PCR amplification of the translocated ABL1 kinase domain followed by direct sequencing of the entire amplified kinase domain. The objective of this review is to highlight the importance of regular and timely CCA, FISH analysis and molecular testing in the diagnosis, prognosis, assessment of therapeutic efficacy, evaluation of MRD and in the detection of BCR-ABL1 kinase mutations which cause therapeutic resistance in adult CML patients.

Gene therapy: An updated overview on the promising success stories

Gene therapy is a method of treatment of disease aimed at its molecular level. The progress of gene therapy, however, was as promising as it was tardy mainly due to the limitations in the resources and financial part of its development as well as owing to the rarity of most diseases it can offer its benefits to. The methods of gene therapy can vary depending on factors such as the physiology of tissue of interest, affinity of vectors to a certain type of cells, depth and accessibility of the tissue of interest, and size of the gene to be replaced or edited. The concept behind gene therapy has inspired scientists and clinicians alike leading to a rapid expansion of its clinical utility that has become so widespread to not only include diseases of monogenic origin, but also polygenic diseases, albeit not so commonly. This article delves into notable success stories of gene therapy which has been regarded as the beacon of medical novelty expected to blossom in the near future to provide a holistic, targeted, precise, and individualistic personalised-medicine as well as laying out the future hopes of gene therapy in the treatment of debilitating diseases such as solid tumours, AIDS, Tuberculosis, Diabetes Mellitus, psychiatric illnesses, which are still at a standstill, from a gene therapy point of view.

Micro-RNA Expression Profiling in Malaysian Triple-Negative Breast Cancer Patients: Impact on Recurrence Prediction

Background: Triple negative breast cancer (TNBC) is characterized by its biologic aggressiveness, worse prognosis and lack of therapeutic targets. Due to high probability of tumor recurrence and also due to lack of available targeted therapies, TNBC patients are treated with standard chemotherapy using TAC [taxane (T), adriamycin (A) and cytoxan (C)] chemotherapy regimen. However, TNBC patients present significant interindividual differences of treatment efficacy. Drug resistance and recurrence remains major clinical obstacles to successful treatment in many TNBC patients. This warrants the need for early identification of TNBC patients who are likely to be chemosensitive and those who have high recurrence risk. TNBC may have specific molecular features that could be possible targets for new biologic targeted drugs. microRNAs (miRNAs) which are aberrantly expressed in tumors, can target and modulate key genes involved in TNBC chemotherapy. Aberrant microRNA expression is strongly implicated in anticancer drug resistance phenotype and hence, miRNAs appear to be promising candidates for response and recurrence prediction. Aim: To investigate the expression profile of few candidate miRNAs (miR-21, miR-27b, miR-34a, miR-182, miR-200c and miR-451) in tumourous and nontumourous tissues in Malaysian TNBC patients and their utility as predictive markers of recurrence in TNBC patients. Methods: Malaysian TNBC patients who had undergone TAC chemotherapy regimen at Hospital Universiti Sains Malaysia were identified and the clinicopathological variables were recorded. Total RNA from cancerous and adjacent noncancerous tissues of FFPE samples from 41 patients were isolated, transcribed and preamplified. The expression of selected miRNAs (miR-21, miR-27b, miR-34a, miR-182, miR-200c and miR-451) were quantified using quantitative real-time PCR (qRT-PCR). The miRNAs expression was categorized into two groups based on upregulation and downregulation. The disease outcome of the patients were evaluated after completion of chemotherapy. Disease-free survival (DFS) analysis using Kaplan-Meier method followed by univariate and multivariate Cox's regression analysis were performed to investigate the impact of these candidate miRNAs on recurrence prediction. Results: The relative expressions of miR-27b and miR-451 were found to be significantly lower in cancerous as compared with normal adjacent tissues of TNBC patients. Multivariate Cox's regression analysis demonstrated that medullary and metaplastic tumor subtypes and positive axillary lymph nodes significantly increased the risk of recurrence in TNBC patients. Downregulated expression of miR-21 and upregulated expression of miR-182 were found to be associated with risk of recurrence in TNBC patients. Conclusion: Tumor subtypes, positive axillary lymph nodes as well as expression profiles of miR-21 and miR-182 could be useful as predictive biomarkers of recurrence in TNBC patients.

Micro-RNA Expression Profiling in Malaysian Triple-Negative Breast Cancer Patients: Impact on Recurrence Prediction

Background: Triple negative breast cancer (TNBC) is characterized by its biologic aggressiveness, worse prognosis and lack of therapeutic targets. Due to high probability of tumor recurrence and also due to lack of available targeted therapies, TNBC patients are treated with standard chemotherapy using TAC [taxane (T), adriamycin (A) and cytoxan (C)] chemotherapy regimen. However, TNBC patients present significant interindividual differences of treatment efficacy. Drug resistance and recurrence remains major clinical obstacles to successful treatment in many TNBC patients. This warrants the need for early identification of TNBC patients who are likely to be chemosensitive and those who have high recurrence risk. TNBC may have specific molecular features that could be possible targets for new biologic targeted drugs. microRNAs (miRNAs) which are aberrantly expressed in tumors, can target and modulate key genes involved in TNBC chemotherapy. Aberrant microRNA expression is strongly implicated in anticancer drug resistance phenotype and hence, miRNAs appear to be promising candidates for response and recurrence prediction. Aim: To investigate the expression profile of few candidate miRNAs (miR-21, miR-27b, miR-34a, miR-182, miR-200c and miR-451) in tumourous and nontumourous tissues in Malaysian TNBC patients and their utility as predictive markers of recurrence in TNBC patients. Methods: Malaysian TNBC patients who had undergone TAC chemotherapy regimen at Hospital Universiti Sains Malaysia were identified and the clinicopathological variables were recorded. Total RNA from cancerous and adjacent noncancerous tissues of FFPE samples from 41 patients were isolated, transcribed and preamplified. The expression of selected miRNAs (miR-21, miR-27b, miR-34a, miR-182, miR-200c and miR-451) were quantified using quantitative real-time PCR (qRT-PCR). The miRNAs expression was categorized into two groups based on upregulation and downregulation. The disease outcome of the patients were evaluated after completion of chemotherapy. Disease-free survival (DFS) analysis using Kaplan-Meier method followed by univariate and multivariate Cox's regression analysis were performed to investigate the impact of these candidate miRNAs on recurrence prediction. Results: The relative expressions of miR-27b and miR-451 were found to be significantly lower in cancerous as compared with normal adjacent tissues of TNBC patients. Multivariate Cox's regression analysis demonstrated that medullary and metaplastic tumor subtypes and positive axillary lymph nodes significantly increased the risk of recurrence in TNBC patients. Downregulated expression of miR-21 and upregulated expression of miR-182 were found to be associated with risk of recurrence in TNBC patients. Conclusion: Tumor subtypes, positive axillary lymph nodes as well as expression profiles of miR-21 and miR-182 could be useful as predictive biomarkers of recurrence in TNBC patients.

Clinical impact of ABCC1 and ABCC2 genotypes and haplotypes in mediating imatinib resistance among chronic myeloid leukaemia patients

WHAT IS KNOWN AND OBJECTIVE

The introduction and success of imatinib mesylate (IM) has brought about a paradigm shift in chronic myeloid leukaemia (CML) treatment. However, despite the high efficacy of IM, clinical resistance develops due to a heterogeneous array of mechanisms. Pharmacogenetic variability as a result of genetic polymorphisms could be one of the most important factors influencing resistance to IM. The aim of this study was to investigate the association between genetic variations in drug efflux transporter ABCC1 (MRP1) and ABCC2 (MRP2) genes and response to IM in patients with CML.

METHODS

We genotyped 215 Malaysian patients with CML (comprising of two groups with 108 IM resistant and 107 IM responsive) for polymorphisms of ABCC1 (2012G>T and 2168G>A) and ABCC2 (-24C>T, 1249G>A and 3972C>T) genes. Genotype, allele and haplotype frequencies were compared between two groups of patients. Patients with CML were further stratified according to their clinical response to IM into those having cytogenetics and molecular responses, and the associations with genotypes were evaluated.

RESULTS AND DISCUSSION

We observed no significant differences in the distribution of any of the tested genotypes between the investigated groups. However, on evaluating the risk association, ABCC2 T₋₂₄ G₁₂₄₉ T₃₉₇₂ haplotype was found to be associated with IM resistance (P = 0·046). These results suggest that haplotype variants -24T and 3972T might be associated with lower expression of ABCC2 protein and reduced transport activity and hence might be contributing to development of IM resistance.

WHAT IS NEW AND CONCLUSION

Our results suggest the ABCC2 T₋₂₄ G₁₂₄₉ T₃₉₇₂ haplotype was associated with imatinib resistance. However, the evidence is as yet insufficient to establish this haplotype as a predictive biomarker for response to the drug.

Somatic copy-neutral loss of heterozygosity and copy number abnormalities in Malaysian sporadic colorectal carcinoma patients

Colorectal cancer is one of the most common cancers in many countries, including Malaysia. The accumulation of genomic alterations is an important feature of colorectal carcinogenesis. A better understanding of the molecular events underlying the stages of colorectal carcinogenesis might be helpful in the detection and management of the disease. We used a commercially available single-nucleotide polymorphism genotyping array to detect both copy number abnormalities (CNAs) and copy-neutral loss of heterozygosity (LOH) in sporadic colorectal carcinomas. Matched tumor and normal tissues of 13 colorectal carcinomas (Dukes' stages A-D) were analyzed using a 250K single nucleotide polymorphism array. An additional assay was performed to determine the microsatellite instability status by using the National Cancer Institute-recommended BAT-26 panel. In general, copy number gain (92.3%) was most common, followed by copy number loss (53.8%) and copy-neutral LOH (46.2%). Frequent CNAs of gains and losses were observed on chromosomes 7p, 8, 13q, 17p, 18q, and 20q, and copy-neutral LOH was observed on chromosomes 2, 6, 12, 13q, 14q, 17, 20p, 19q, and 22q. Even though genomic alterations are associated with colorectal cancer progression, our results showed that DNA CNAs and copy-neutral LOH do not reflect disease progression in at least 50% tumors. Copy-neutral LOH was observed in both early and advanced tumors, which favors the involvement of these genomic alterations in the early stages of tumor development.

Chromosomal abnormalities and reproductive outcome in Malaysian couples with miscarriages

INTRODUCTION

This study was done to determine the prevalence of chromosomal abnormalities and the subsequent reproductive outcome in couples who had two or more miscarriages.

METHODS

56 couples with a history of at least two previous miscarriages were evaluated for prevalence and types of chromosomal abnormalities from their karyotype records. The study was a retrospective one, and subsequent reproductive outcome after a period of 12-24 months from the time of karyotyping was obtained by telephone interviews and scrutiny of the case records. The comparison of reproductive outcome was done by chi-square statistics.

RESULTS

Five couples (8.9 percent) had a chromosomal abnormality in one partner. Three cases of reciprocal translocations t(5;11), t(9;14), dup(9q); one Robertsonian D/D translocation 13/14; and one mosaic Down syndrome male karyotype were found. Among the 32 couples available for follow-up, there was a lower incidence of subsequent live healthy births among chromosomally-normal couples (35.7 percent) compared to chromosomally-abnormal ones (25 percent). However, the difference was not statistically significant (p-value is 1.0). There was a lower incidence of subsequent abortions in chromosomally-normal couples (42.8 percent) compared to chromosomally-abnormal ones (50 percent), but the difference was also not statistically significant (p-value is 1.0).

CONCLUSION

Chromosomal abnormalities were seen in 8.9 percent of the couples, and translocations were the commonest abnormality found. The frequencies of subsequent live healthy births and subsequent abortions showed no significant difference between couples having normal karyotypes and those having chromosomal abnormality in one partner.

Clinical manifestations in trisomy 9

Complete trisomy 9 is a lethal diagnosis and most fetuses diagnosed thus die prenatally or during the early postnatal period and majority of such cases have been known to end in spontaneous abortion in the first trimester itself. One such rare survival of fetus ending in normal delivery and surviving until 20 days is reported here detailing the clinical manifestations of the child during the period of survival. The salient clinical features observed were small face, wide fontanel, prominent occiput, micrognathia, low set ears, upslanting palpebral fissures, high arched palate, short sternum, overlapping fingers, limited hip abduction, rocker bottom feet, heart murmurs and also webbed neck, characteristic of this trisomy 9 syndrome.

Two cases of deletion 5p syndrome: one with paternal involvement and another with atypical presentation

We report two cases of deletion 5p or cri du chat syndrome (CdCS) with different presentations and risks of transmission: one case with paternal chromosome 5 involvement and another, a de novo case with atypical clinical presentation. Cytogenetic analysis was performed on the two cases and their parents. GTG-banded karyotype analysis of Cases 1 and 2 revealed abnormal 46,XY,del(5)(p13-15) male karyotypes. For Case 1, the mother showed normal female karyotype while the father showed an abnormal karyotype involving a balanced translocation 46,XY,t(5;10)(p13;p15). For Case 2, however, both parents showed a normal karyotype pattern. In Case 1, the clinical features, particularly the distinct facial phenotype in combination with a characteristic cat-like cry and hypotonia, aided in the diagnosis at birth and the karyotype analysis was resolutive. The boy in Case 2 presented with atypical clinical features. Even though this patient had multiple syndromic features, the typical high pitched cat-like cry was not prominent. Instead, the patient manifested persistent stridor (from day three of life), which might have prevented the clinician from suspecting CdCS at birth. However, when this patient was presented at seven months of age for cytogenetic analysis, a confirmatory diagnosis of CdCS was established. For children with congenital abnormalities, an early clinical diagnosis confirmed through cytogenetic and molecular investigations, is important for providing personalised diagnostic and prognostic evaluation, and also for genetic counselling on the reproductive risk, particularly for patients with parental chromosome translocation involvement.

Screening of dystrophin gene deletions in Malaysian patients with Duchenne muscular dystrophy

Duchenne Muscular Dystrophy (DMD) is an X-linked recessive genetic disorder characterized by rapidly progressive muscle weakness. The disease is caused by deletion, duplication or point mutation of the dystrophin gene, located on the X chromosome (Xp21). Deletion accounts for 60% of the mutations within the 79 exons of the dystrophin gene. Seven exons (43, 44, 45, 46, 49, 50, and 51) were found to be most commonly deleted among the Asian patients. To detect the frequency of deletion of these 7 exons in Malaysian DMD patients, we carried out a molecular genetic analysis in 20 Malaysian DMD patients. The mean age of initial presentation was 60 months (SD 32 months, range 5-120 months). Fourteen patients were found to have deletion of at least one of the seven exons. The remaining six patients did not show any deletion on the tested exons. Deletions of exons 49, 50 and 51 were the most frequent (71.43%) and appear to be the hot spots in our cohort of patients.

Germline BRCA1 mutation and survival analysis in familial breast cancer patients in Kerala; South India

Mutations in breast cancer susceptibility gene BRCA1 have been identified in breast or breast/ovarian cancer families from different ethnic background. We analyzed a total of 79 samples for BRCA1 mutation, using Conformation Sensitive Gel Electrophoresis (CSGE) followed by sequencing. The overall survival of BRCA1 mutation carriers was also investigated. BRCA1 mutation was detected in 11 out of the 29 (38%) patients. Four different alterations were detected of three which were novel. A missense mutation in exon 7, 465G>A was detected in 1 patient (9%). Another missense mutation 932 G>A was observed in three patients (27.3%) and a truncation mutation 1027delA, was observed in one patient (9%). The fourth type of mutation (185delAG) which also results in protein truncation was observed in 6 different patients (54.5%). Kaplan-Meier survival analysis revealed a median overall survival of 34 months for BRCA1 mutation positive breast cancer patients and 71 months for BRCA1 negative breast cancer patients. The median overall survival of BRCA1 truncation mutation carriers was 26 months. Our data showed high prevalence of BRCA1 gene mutation among breast or breast/ovarian cancer families in South India and breast cancer patients having BRCA1 mutations were associated with poor prognosis.

Cytogenetic and clinical profile of Down syndrome in Northeast Malaysia

INTRODUCTION

This study was designed to evaluate the karyotype pattern, clinical features and other systemic anomalies of patients with Down syndrome in Malaysia.

METHODS

Retrospective analysis was performed on the case records of 149 patients confirmed as Down syndrome by cytogenetic analysis at Human Genome Centre and Genetic Clinic at the Universiti Sains Malaysia.

RESULTS

Among the 149 cases of Down syndrome presenting over a period of 4.2 years, free trisomy (non-disjunction) was present in 141 cases (94.6 percent). One case (0.7 percent) had translocation, and seven cases (4.7 percent) were mosaics. Average age at presentation was 10.6 months. Average maternal age at birth of the affected child was 32.3 years. The prominent craniofacial features noted were upslanting palpebral fissures (89.3 percent), flat facial profile (64.9 percent), low set ears (56.1 percent), epicanthic folds (17.5 percent) and protruding tongue (19.2 percent). A total of 52.6 percent of the cases had documented hypotonia. Characteristic limb and dermatoglyphic anomalies included short stubby fingers (24.5 percent), sandal gap (33.3 percent), unilateral or bilateral simian crease (36.8 percent) and clinodactyly (19.2 percent). Ophthalmological abnormalities, such as hypertelorism, were presented in 33.3 percent of the cases. Congenital heart disease was diagnosed in 35 out of 71 cases (49.3 percent) and gastrointestinal anomalies were noted in 18 out of 79 cases (22.7 percent) analysed.

CONCLUSION

Efforts to establish early diagnosis and a proper screening for high association with systemic anomalies should be undertaken among the Down syndrome patients in this population.

Two cases of isochromosome 18q syndrome

Patients with isochromosome 18q, a rare cytogenetic abnormality, also reported as Edwards syndrome, is the second most common autosomal trisomy. However, the phenotypic features and survival of these patients are not uniform and depend upon the portion of chromosomes getting duplicated or deleted. The survival of these children may be longer, hence a good cytogenetic diagnosis is a must. Morphological characteristics of isochromosome 18q are not yet fully delineated because of the rarity of the cases and as most cases are aborted medically or terminate spontaneously. We report two cases of isochromosome 18q, one male aged two years old and the other a male aged eight months old, and review the literature on this rare syndrome.

Expression of folate sensitive and aphidicolin induced chromosomal fragile sites in familial neuroblastoma

The expression of folate sensitive and aphidicolin induced fragile sites in the blood lymphocyte chromosomes of affected and unaffected members from 2 neuroblastoma families were studied. The subjects included 4 neuroblastoma patients, and 9 of their clinically healthy first degree relatives and corresponding number of age and sex matched controls. Lymphocytes cultured in folate deprived culture medium showed rare fragile sites at band p13.1 of chromosome 1, in a frequency of 3%-5% in all the 4 neuroblastoma patients. In aphidicolin treated cultures, the patients and unaffected members in neuroblastoma families, showed hypersensitivity to aphidicolin, as evidenced by the significant increase in percentage of aberration/cell (ab/c) and damaged cells (dc), over that of controls (P < 0.01). Aphidicolin induced fragile sites were more pronounced in chromosomes 1 and 2. A larger number of subjects have to be studied to prove whether altered fragile site expression may be a cytogenetic evidence for an individual or familial cancer predisposing genetic constitution.

Deficient DNA repair capacity: a predisposing factor and high risk predictive marker in familial colorectal cancer

Even though colorectal cancer tends to aggregate in families, there is paucity of information on the genetic determinism for familial colorectal cancer (FCRC) predisposition. Therefore, we investigated constitutional chromosome abnormalities and bleomycin induced chromosome sensitivity of 26 familial and 30 sporadic colorectal cancer (SCRC) patients, 60 unaffected family members (first/second degree relatives) and 30 normal healthy controls to determine whether these parameters could give any clues on genetic predisposing factors by which high risk members in CRC families could be identified. The test assay used bleomycin-induced chromatid breaks in short term microcultures of peripheral blood lymphocytes of the subjects. The CRC patients, the unaffected family members and the controls did not show any constitutional chromosomal abnormalities. However, with regard to bleomycin sensitivity, there was significant difference between the CRC patients, unaffected relatives and controls. The mean b/c values of 1.64+/-0.42 for the FCRC patients and 1.08+/-0.34 for the SCRC patients were significantly higher than the mean b/c values of 0.62+/-0.18 for the unaffected relatives and 0.52+/-0.12 for the controls (P<0.001). A noteworthy observation was that 6 unaffected members from 6 CRC families also showed bleomycin hypersensitivity, at the initiation of the study. Since they expressed mean b/c values greater than 1.0, which was as high a value as those of the patients, they were regularly followed up. Out of these 6 members, 2 developed CRC later. This clearly demonstrates that mutagen hypersensitivity among unaffected relatives in CRC families may be related to cancer predisposition. Hence, this cytogenetic assay could be utilised to identify the genetically high risk individuals in CRC families.

The cytogenetic identification of high risk members in colorectal cancer families

Family history of colorectal cancer is recognized as a risk factor for the disease and the development of colorectal cancer represents a suitable model for illustrating multistep tumor development. Bleomycin induced chromosome sensitivity studies were done in 7 colorectal cancer families consisting of 12 colorectal cancer patients and their 34 first degree relatives and 12 sporadic colorectal patients for comparison and identification of high risk family members with genetic instability. All patients and 4 unaffected relatives showed increased bleomycin sensitivity, which might be due to defective DNA repair system. These four relatives may be classified as high risk (without cancer at present) individuals. The study is being continued in more number of familial colorectal cancer patients and their relatives to arrive at definite conclusions.

DNA repair proficiency: a potential marker for identification of high risk members in breast cancer families

Breast cancer is the single largest cancer and causes the high rate of cancer mortality among women. A positive family history of breast cancer is recognized as one of the major risk factors for this disease. The present study evaluates bleomycin (BLM)-induced chromosome sensitivity analysis in breast cancer families which provides indirectly a measure of the DNA repair defect of each person. BLM sensitivity assay on cultured lymphocytes of 36 familial breast cancer patients, their 85 first or second degree female relatives, 36 sporadic breast cancer patients and 40 age- and sex-matched controls (without any family history of cancer) were carried out to measure interindividual variation in their DNA repair capacity through mutagen-induced chromosome sensitivity analysis. Fifty percent of familial breast cancer patients and seven unaffected relatives showed hypersensitivity. Compared to hyposensitive relatives these seven subjects may be considered as high risk individuals.

Increased levels of mutagen-induced chromosome breakage in Down syndrome children with malignancy

Even though an association between Down syndrome (DS) and malignancies has been established, the mechanism behind this is still unclear. We therefore investigated constitutional chromosomal abnormalities and bleomycin-induced chromosome sensitivity in 12 DS children, 8 DS children with malignancies, and 10 normal controls to explore whether these factors play any role in cancer predisposition. Trisomy 21 was the only constitutional cytogenetic abnormality observed in all the DS children. But there was significant variation between the patients and controls with regard to bleomycin sensitivity. Compared to the normal controls, all the DS patients expressed significantly higher chromosomal breaks per cell (b/c) values indicating sensitivity to bleomycin. Furthermore, DS children with malignancies demonstrated significantly higher b/c values than DS children with malignancies. These results permit us to assume that DS children showing mutagen hypersensitivity may be having defective DNA repair competence and hence may be predisposed to malignancies.

Malignancies in Down syndrome

Down Syndrome (DS) is associated with an increased incidence of malignancies, especially leukaemias. We came across 8 DS children presenting with malignancies and having trisomy 21 as the sole cytogenetic abnormality. Of these 8 DS cases, 4 presented with acute lymphocytic leukaemia, 2 with acute myeloid leukaemia and one case each with Hodgkin's disease and Wilms' tumour. There are contradictory reports regarding the distribution of myeloid versus lymphoid malignancies in DS children and their response to therapy. The exact mechanism by which patients with DS are predisposed to develop malignancies is unclear. However, presence of the extra chromosome no. 21 is presumed to disrupt the genetic balance which increases generalized susceptibility to genetic and environmental trauma. Furthermore, an increased methotrexate toxicity observed in these patients should also be taken into consideration in designing treatment for DS children with malignancies.

Mutagen sensitivity as a predisposing factor in familial oral cancer

Pedigree analysis of the oral cancer (OC) patients registered at our Centre had disclosed familial aggregation of oral cancer which hitherto has not been largely reported. There is a paucity of information on the genetic determinism for familial oral cancer predisposition. Therefore, we investigated constitutional chromosome abnormalities and bleomycin-induced chromosome sensitivity of 7 familial and 10 sporadic oral cancer patients and 14 unaffected family members (first-degree relatives) to determine whether these factors could give any clues regarding cancer-predisposing factors. Neither the oral cancer patients nor the unaffected family members showed any constitutional chromosomal abnormalities. However, with regard to bleomycin sensitivity, there was significant difference between the oral-cancer patients and unaffected relatives. The mean b/c value was 1.68 +/- 0.48 for familial OC patients, 1.12 +/- 0.36 for sporadic OC patients and 0.52 +/- 0.18 for the unaffected family members (p < 0.001). A noteworthy observation was that one unaffected family member also showed bleomycin hypersensitivity and expressed a mean b/c value of 1.32, at the initiation of the study. That patient later developed oral carcinoma. This clearly demonstrates that mutagen hypersensitivity among unaffected relatives in OC families may be related to cancer predisposition. The mutagen sensitivity study is being continued in a larger series of subjects, for the development of a cytogenetic marker for prediction of cancer susceptibility.

Clinical implications of cytogenetic classification in adult acute lymphoblastic leukaemia patients

Cytogenetic analysis performed on pretreated unstimulated, bone marrow/peripheral blood samples of 46 adult patients with acute lymphoblastic leukaemia (ALL) showed sufficient metaphases in 39 patients and insufficient metaphases in 7 patients. G-banded karyotype analysis of these 39 patients revealed non-random clonal chromosome abnormalities in 31 patients and apparently normal karyotypes in 8 patients. Numerical abnormalities involving chromosome trisomies and structural abnormalities involving different types of chromosomal translocations and deletions were encountered in varying percentages. These patients were grouped into various cytogenetic subsets on the basis of their karyotype pattern and followed-up to evaluate their prognosis. Patients with apparently normal karyotypes showed good prognosis and those with 6q- showed intermediate prognosis. But all other patients with hyperdiploid, pseudodiploid and hypodiploid karyotypes were associated with poor prognosis. Cytogenetic classification of ALL patients is thus of clinical importance, as it helps the early identification of clinically important prognostic groups.

Is oral cancer susceptibility inherited? Report of five oral cancer families

All the oral cancer patients registered at the Regional Cancer Centre, Trivandrum, during January to July 1995 were subjected to detailed pedigree analysis. This revealed that oral cancer tends to aggregate in families. Like other familial cancers, a family history of oral cancer was associated mostly with an early age of onset of the disease. Family members without habits such as tobacco chewing, smoking or alcohol consumption were also affected. These observations prompt us to suggest the probable inheritance of an oral cancer susceptibility gene in these families. The familial aggregation, mostly site-specific, with an autosomal dominant mode of inheritance, was observed in 0.94% of the total oral cancers. This necessitates the need to undertake studies to elucidate the molecular lesions responsible for oral cancer susceptibility in families.

Nonrandom karyotype abnormalities in 36 multiple myeloma patients

G-banded analysis performed on pretreated bone marrow samples of 36 multiple myeloma patients allowed the identification of clonal chromosome abnormalities. Abnormalities consisting of trisomies, monosomies, translocations, deletions, and marker chromosomes apparently followed a nonrandom pattern. The chromosomes involved in the production of abnormal karyotypes were numbers 1,2,3,11,12,14,17, and 18. Even though no specific chromosome pattern has been identified, the involvement of chromosomes 1, 3, and 14 was found to be more frequent. Many of the chromosomes and chromosomal breakpoints involved in these abnormalities correspond to the location of identified oncogenes or tumor suppressor genes. Hence, it is presumed that these chromosome abnormalities may be playing an important role in the genesis of multiple myeloma by altering the structure or function of oncogenes or tumor suppressor genes.

Mandibulofacial dysostosis. Case report

A case of mandibulofacial dysostosis (Treacher Collins syndrome) is presented. Clinical features and skull radiographs revealed typical anomalies associated with the syndrome. Cleft of the soft palate and unerupted multiple supernumerary teeth were present in this case. No haematological, biochemical or immunological abnormalities could be detected in the patient. Pedigree analysis showed an autosomal dominant mode of transmission of the disease. Chromosomal studies did not reveal any structural or numerical discrepancies.

Chromosomal aberrations induced by methyl parathion in human peripheral lymphocytes of alcoholics and smokers

1 Two different concentrations (0.08 and 0.16 micrograms ml-1) of methyl parathion (MP), a broad-spectrum insecticide, were tested on peripheral lymphocytes of healthy non-smoking non-alcoholics (CN), chronic smokers (SM) and alcoholics with smoking habit (ALSM). 2 SM and ALSM revealed a significant increase in chromosome aberration frequencies in peripheral lymphocytes compared to the CN group. 3 MP did not induce chromosomal aberrations in vitro in the CN group at either of the concentrations tested. 4 In SM and ALSM, MP induced a significant increase in chromosomal aberrations in vitro in peripheral lymphocytes at a concentration of 0.16 micrograms ml-1. 5 The results indicate that the damage induced by MP in peripheral lymphocytes is potentiated by smoking and alcohol intake.

Prognostic significance of karyotype analysis in children with acute lymphoblastic leukemia

Chromosome studies, using bone marrow samples of 26 pretreated children (below 15 years of age) with Acute Lymphoblastic Leukemia were carried out to explore the potentialities of applying chromosomal findings as a prognostic indicator in these patients. Abnormal karyotype was identified in 15 patients (57.6 per cent). The chromosomes frequently involved in non-random numerical abnormalities were Nos. 8, 18 and 21. Structural chromosome changes observed consisted of deletion 6q- and translocation t (4;11). After karyotype analysis, patients were grouped into subsets on the basis of the karyotype pattern observed. They were followed up to evaluate their prognosis and survival period. Patients showing hyperdiploid clone with greater than 51 chromosomes had the best prognosis. Patients with normal karyotype and patients with deletion of the long arm of chromosome 6 showed intermediate prognosis whereas patients showing t (4;11), trisomy 8, trisomy 18, trisomy 21, and hypodiploid karyotype were associated with worst prognosis. Thus, karyotype analysis before treatment helps to classify ALL patients as poor, intermediate and good prognosis groups and on this basis therapy can be designed accordingly.

Sister chromatid exchange frequencies in carcinoma of the human oral cavity: effect of treatment

Spontaneous and mitomycin-C-induced sister chromatid exchange frequencies were studied in the lymphocytes of 25 oral cancer patients. For these patients, the mean spontaneous SCE value was 8.31 (+/- SD), which was significantly higher than the value of 6.60 (+/- SD) obtained for the controls (p < 0.001). But there was no significant difference between the Mitomycin C induced mean SCE values of oral cancer patients and controls. Seven of these 25 oral cancer patients were selected for second sampling after surgical removal of the tumor. Six of these seven patients showed a decrease in mean SCE/cell value following surgery, which was almost equal to the SCE values obtained for the controls. This indicates that the increased spontaneous SCE rates in oral cancer patients might be due to the metabolic stress imposed by the tumor on the host body or by some clastogenic product of the malignant cells. Surgical removal of the tumour might have resulted in normalization of the lymphocytic SCE rates in postoperatively studied patients.

Molecular pathogenesis of chronic myelogenous leukaemia

Chronic myelogenous leukaemia is a clonal neoplasm of the pluripotent haematopoietic stem cell which is characterized in most patients by a consistent cytogenetic abnormality known as the Philadelphia chromosome. This chromosome occurs as a consequence of a reciprocal translocation between the long arms of chromosomes 9 and 22 which results in the creation of a new gene comprising sequences from the c-abl gene on chromosome 9 and the bcr gene on chromosome 22. The protein encoded by this structurally altered hybrid gene differs from the normal c-abl gene product in both molecular weight and in tyrosine kinase activity. It is likely that these alterations in the c-abl gene product play a central role in the pathogenesis of this leukaemia.

Molecular cytogenetics of human cancer

Cancer may arise from the genetic transformation of a single precursor cell, which proliferates to form a clone. Chromosomal abnormalities are associated with many types of tumours. Some of the chromosomal rearrangements such as translocation, deletion and insertion involve breakage of chromosomes close to known oncogenes. The close linkage between the chromosomal changes, the gene modifications and consequently altered protein function seen in malignant cells suggest that cancer is a genetic disease. Analysis of chromosomal abnormalities and oncogene amplifications in malignant cells have been found to be related to their malignant potential and hence may be utilized in the clinical management of patients with cancer.

Circulating immune complexes in localised juvenile periodontitis

This study determined the quantity and type of circulating immune complexes (CIC) in the sera of 15 patients with localised juvenile periodontitis (LJP). There was a significantly higher level IgG and IgM in LJP patients as compared with the controls. The possible role of CIC in the pathogenesis of juvenile periodontitis is discussed.

Cell-mediated and humoral immune responses in patients with localized juvenile periodontitis

Cell-mediated and humoral immune responses were assessed in 21 patients with localized juvenile periodontitis (LJP), and in an equal number of control subjects. The cell-mediated immunity, assessed by enumeration of total rosette forming cells [TRFC] and high affinity rosette forming cells [HARFC], was found to be depressed in LJP patients compared to controls. Estimation of serum immunoglobulins G,A,M,D and E levels were done using single radial immunodiffusion. All the immunoglobulins except IgD were found to be elevated significantly in LJP patients. The defective immune response found in LJP patients may be the cause or effect of the disease process. Further investigations are necessary to determine whether these defects are genetically controlled.

Jack fruit lectin binding pattern in benign and malignant lesions of the breast

N-acetyl D-galactosamine specific lectin was isolated from Jack fruit (Artocarpus integrifolia) and conjugated to horse radish peroxidase type VI. The purified conjugate was used for the study of tissue binding properties on benign and malignant lesions of the breast using diaminobenzidine as substrate on dewaxed tissue sections. Forty mammary carcinomas, 10 cystic hyperplasias of the breast and 10 normal breast tissues were used for the study. Neoplastic cells showed increased affinity to the lectin. The lectin binding was focally strong in neoplastic cells compared to the normal as well as the hyperplastic tissues. The stroma of the cancer tissues showed an intense strong binding where elastosis was present. The use of the lectin as a histochemical reagent is discussed.

Circulating immune complexes as an immunological marker in premalignant and malignant lesions of the oral cavity

Circulating immune complexes and their immunoglobulin contents were estimated in the sera of 50 patients with oral leukoplakia, 50 patients with oral submucous fibrosis and 50 oral cancer patients. The values were compared with that of 50 normal controls. The circulating immune complexes and their immunoglobulin contents were found to be elevated significantly both in oral submucous fibrosis and oral cancer. This study seems to be of help in monitoring the malignant transformation of oral submucous fibrosis to oral cancer.

Total hemolytic complement (CH50) and its fractions (C3 and C4) in the sera of patients with carcinoma of the oral cavity, uterine cervix, and breast

The total hemolytic complement activity of CH50 and its fractions C3 and C4 was determined in the sera of 196 patients with carcinoma of the oral cavity, 172 patients with carcinoma of the uterine cervix, and 166 patients with breast cancer. The values were compared with those of 18 patients with mammary dysplasia, 32 patients with mild to moderate dysplasia of the cervix, and 100 healthy, normal age- and sex-matched controls. No alterations in CH50, C3, and C4 were observed in the sera of patients with benign lesions, whereas a significant rise in the three factors was observed in all the cancer patients studied. The complement activity increased significantly with the progression of the disease up to stage III and remained persistently elevated thereafter. Patients who had a clinical cure had normal levels of CH50, C3, and C4, whereas the values remained elevated in patients who were still undergoing treatment for residual lesions.

Cell mediated and humoral immune responses in oral submucous fibrosis

Cell-mediated and humoral immune responses were assessed in 50 patients with oral submucous fibrosis (OSMF) and the results were compared with those of 50 patients with oral-leukoplakia, 50 oral cancer patients, and 50 normal healthy adult controls. The number of high-affinity rosette-forming cells (HARFC) was found to be significantly decreased in OSMF and oral cancer, whereas the number of total rosette-forming cells (TRFC) remained unaltered. Levels of serum IgA, IgD, and IgE were found to be elevated both in OSMF and oral cancer. Immunologic derangements were found to be more pronounced in oral cancer than in OSMF. The enumeration of HARFC along with the estimation of serum levels of IgA, IgD, and IgE indicates that OSMF can be an intermediary stage in the malignant transformation of a normal cell, and that these parameters may serve as markers for the early detection of oral cancer.

Serum immunoglobulins in patients with carcinoma of the oral cavity, uterine cervix and breast

Serum immunoglobulin levels (IgG, IgA, IgM, IgD and IgE) were estimated in 196 patients with carcinoma of the oral cavity, 172 patients with cervical cancer and 166 patients with breast cancer. The values were compared with those of 50 patients with benign lesions of the breast and cervix and 100 healthy adult controls. Only the serum IgE levels were found to be elevated in the benign group. Serum IgA, IgD and IgE levels were found to be elevated in all the three types of cancers and the levels were found to increase with clinical stage. In carcinoma of uterine cervix IgG levels were also found to be elevated. Immunoglobulins A and D returned to normal after clinical cure whereas IgE remained slightly elevated. IgD and IgE remained high in patients who had residual cancer.