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Biomedical subjects

R S Verma

Publications and source records attributed to R S Verma.

At least 55 records · Page 3Linked to original sources
PubMed1997

Rapid denaturation improves chromosome morphology and permits multiple hybridizations during fluorescence in situ hybridization.

Denaturation of chromosomal DNA for fluorescence in situ hybridization (FISH) is an essential step in a procedure associated with a number of variables. In our experience, shorter denaturation time in 70% formamide/2 x SSC at 72 C provides sufficient denaturation, where the hydrogen bonds are broken between the purines and pyrimidines of the double helix. This shortened exposure improves retention of morphology of human chromosomes from lymphocytes, aminocytes, fibroblasts and bone marrow, and allows the same metaphases to be denatured repeatedly and rehybridized with different probes. This approach is useful in investigations where sample volume is limited.

Chromosomes, Human↗
PubMed1997

Characterization of an isodicentric Y-chromosome for the long arm in a newborn with mixed gonadal dysgenesis.

A newborn infant was referred for evaluation because of ambiguous genitalia. Examination of the genitalia revealed a hypospadiac phallus measuring 1.5 cm in length with chordee. Subtle phenotypic features consistent with Turner syndrome were present including hypertelorism, anti-mongoloid slant to the eyes, mild widening of the neck, but no definitive webbing, shield like chest and positive cubitus valgus. A pelvic and renal sonogram confirmed the presence of a uterus and normal-appearing kidneys. There was incomplete fusion of the scrotum. No gonads were palpable within the scrotal sac. The patient was assigned a female gender on the basis of the presence of a uterus, the phenotypic appearance of the genitalia and the malignant potential of the gonads. The cytogenetic findings with QFQ-banding revealed an abnormal karyotype, i.e., mos 46,X,idic(Y) (p11.2)[77]/45,X[29]/46,X,idic(Y) (p11?) [2]/ 47,XY,idic(Y)(p11.2)[2]/47,X,idic(Y)(p11.2), + idic(Y)(p11.2)[1]/46,XY[1]. The presence of an abnormal isodicentric Y-chromosome was evaluated by FISH-technique to ensure a finer characterization than routine methods. The genotype-phenotype correlation could not be established since mosaicisms of highly variable nature can exhibit an unpredictable outcome.

Female↗
PubMed1997

Characterization of two extreme variants involving the short arm of chromosome 22: are they identical?

The heteromorphic nature of the short-arms of human acrocentric chromosomes is considered the norm without any dire consequences. We characterized two highly unusual chromosome 22 variants with extremely enlarged short arms by routine and molecular cytogenetic techniques. Routine banding revealed that the two variants were not alike. Therefore, a characterization by fluorescent in situ hybridization (FISH) technique became warranted and revealed their remarkable differences. The first variant apparently had a tandem duplication of bands p11.2-->p13, while the second variant had a loss of the beta-satellite and ribosomal DNA regions with an apparent amplification of the satellite III region. The formation of these extremely enlarged regions can occur by a variety of mechanisms whose clinical significance remains obscure.

Adult↗
PubMed1997

Tandem duplication of chromosome 14 (q12q13).

A nine-years-old Egyptian boy was referred for speech and language delay. He has an I.Q. of 35 which is in the moderately to severely delayed range. Routine cytogenetic and FISH-techniques revealed a de novo tandem duplication of chromosome 14 bands q12 and q13, i.e., 46, XY, dup (14)(q12q13) and there are no investigations reporting a direct de novo duplication for this region.

Child↗
PubMed1997

An unusual G-negative band within 1qh region a rare variant or an abnormality?

Morphological variations due to heterochromatic DNA of the secondary constriction region (qh) of human chromosome 1 are considered normal. The structural abnormalities involving or in association within the qh region have been difficult to characterize by routine cytogenetic methods and in turn have often gone undetected. In the past, the presence of a G-negative band within the qh region of chromosome 9 has been considered as a rare or unusual variant. Fortuitously, we were referred two cases where a G-negative band was embedded within the secondary constriction region of chromosome 1. Whole chromosome #1 specific painting probe, did hybridize to the band. Both patients have speech delay. Unfortunately, the parents were not available to confirm the mode of inheritance, nor could a definite conclusion be reached concerning its morbidity. Nevertheless, we are tempted to hypothesize that this is an unusual variant where a G-negative band apparently became genetically inert when it was sandwiched between two blocks of heterochromatin. Similar to a rare variant of chromosome 9 it could be found in the qh region of chromosome 16 as well, whose clinical consequences remain obscure.

Child, Preschool↗
PubMed1996

Assignment of human MYCN proto-oncogene to chromosome band 12q24 in higher primates.

Controversies concerning the reduction of chromosome number from 48 to 46 in humans by putative fusion of two ape chromosomes still persist. Nevertheless, abundant evidence suggests that human chromosome 2 was derived by fusion. Consequently, the recent availability of the human MYCN gene probe which was localized to 2p24.3 facilitated our search for its location in the human equivalent chromosome(s) of chimpanzee (Pan troglodytes), gorilla (Gorilla gorilla) and orangutan (Pongo pygmaeus). In all three species, the human MYCN gene was localized to the long arm of chromosome 12 band 12q24 which is the corresponding band equivalent of the short arm of human chromosome 2. The conservation of MYCN gene in higher primates at the equivalent chromosome locus that corresponds to that of the human provides additional prevailing view towards tracing the evolutionary pathways concerning the origin of chromosome 2, though we recognize that there are conceptual problems concerning human descent.

Animals↗
PubMed1996

T-cell receptor J beta 1/J beta 2 locus rearrangements in an HTLV-1-positive T-cell lymphoma with complex chromosomal aberrations.

We report a case of human T-cell lymphotropic virus type 1 (HTLV-1)-infected adult T-cell lymphoma that has multiple chromosomal abnormalities, including the presence of an additional 7q22-36, which contains the locus of the T-cell receptor (TCR) beta chain gene. Specific TCR J beta 1/J beta 2 gene rearrangements were detected in both marrow and peripheral blood DNA, with evidence of further evolution of the transformed clonal population within the peripheral lymphocytes. To our knowledge, this is the first case in which gene rearrangements have been associated with additional TCR loci. Consequently, it is advised that every effort should be made to correlate chromosomal abnormalities with gene rearrangement by molecular methods.

Adult↗
PubMed1996

Regional localization of human M-BCR gene to chromosome 23 band q11 in the great apes.

We hybridized a human M-BCR DNA probe to the chromosomes of chimpanzee (Pan troglodytes), gorilla (Gorilla gorilla) and orangutan (Pongo pygmaeus) by FISH-technique. The human M-BCR gene was localized to chromosome 23 band q11 (23q11), which is equivalent to the human chromosome 22 band q11 in all three species. The conservation of M-BCR gene in higher primates at the corresponding human chromosome locus provides phylogenetic clues concerning the evolution of genes.

Animals↗
PubMed1996

A unique genomic sequence in the Wolf-Hirschhorn syndrome [WHS] region of humans is conserved in the great apes.

The Wolf-Hirschhorn syndrome (WHS) is caused by a partial deletion in the short arm of chromosome 4 band 16.3 (4p 16.3). A unique-sequence human DNA probe (39 kb) localized within this region has been used to search for sequence homology in the apes' equivalent chromosome 3 by FISH-technique. The WHS loci are conserved in higher primates at the expected position. Nevertheless, a control probe, which detects alphoid sequences of the pericentromeric region of humans, is diverged in chimpanzee, gorilla, and orangutan. The conservation of WHS loci and divergence of DNA alphoid sequences have further added to the controversy concerning human descent.

Abnormalities, Multiple↗
PubMed1996

Genetics of bladder cancer.

Bladder cancer manifests many different forms, ranging from superficial to aggressive muscle invasion, which suggests that various genetic alterations are responsible. Several attempts have been made to establish correlations between specific genetic alterations and various grades of the disease. Numerous types of chromosomal abnormalities have been observed, involving [1p, 1q, 2q, 3p, 4p, 5q, i(5p), +7, +8, 8p, 9p, 9q, 10q23-25, 11p, 11q, +11, 13q, 14q, 17p, 18q, 21q, and Y]. In addition, p53 mutations and loss of heterozygosity on various chromosomes have recently begun to shed light on the molecular pathways of transitional cell carcinomas of the bladder. We have begun to focus on specific genomic sites (especially 9q), although the heterogeneity of the disease and the variable presentation suggests divergent progression pathways. When the genetic basis of bladder cancer is fully understood, new diagnostic and therapeutic strategies will be developed, which in turn may promote better clinical management by pathologists and urologists.

Chromosome Aberrations↗
PubMed1996

Retrieval of aneuploidy by FISH-technique in a case with 46,XX/47,XXX/47,XX,+8.

We report on a 46 year old female with a new chromosomal finding [46,XX/47,XXX/47,XX,+8] who was referred for ovarian failure. The clinical presentation was highly unusual and the patient does not exhibit the characteristic phenotype of trisomy 8 syndrome. Interphase cytogenetics using FISH-technique revealed discrepancies with a different population of cells when compared with its metaphase index. Therefore, it is advised that patients with mosaic karyotypes should be evaluated by analyzing metaphase as well as interphase nuclei labeled with chromosome specific molecular tags, especially in the situations where the incidence of a mosaic cell line is very low. Nevertheless, in a cost-conscious environment, we must exercise caution prior to making universal recommendations concerning the usefulness of medical devices which are increasing at a logarithmic rate.

Aneuploidy↗
PubMed1996

Molecular characterization of an unusual variant of the short arm of chromosome 15 by FISH-technique.

One of the most frequent translocations involving the long arm of chromosome Y with autosomes is with the short arm of chromosome 15. The regions which are involved in this translocation fluoresce brightly, are highly heteromorphic and thus escape detection. Therefore, these abnormalities could not be fully characterized, especially in cases where parents are not available or paternity is disputed. Results from the employment of the selective staining techniques DA/DAPI and Q-banding have been inconclusive. FISH-technique using whole chromosome painting (WCP) probes should be used to decipher such translocations. We present a case where, even after using a battery of probes, the origin of extra material on chromosome 15p could not be identified though it was not a part of Yq.

Chromosomes, Human, Pair 15↗
PubMed1996

Mapping the homolog of the human Rb1 gene to chromosome 14 of higher primates.

The Rb1 gene has been implicated with retinoblastoma and is located on human Chromosome (Chr) 13q14.2. A unique sequence human Rb1 cosmid DNA probe has been used to localize this region on apes' Chr 14 by the FISH technique. The conservation of the Rb1 gene in higher primates at the corresponding equivalent chromosome locus (14q14) of the human may serve as a phylogenetic marker to further trace the evolutionary pathway of human descent.

Animals↗
PubMed1996

Molecular cytogenetic characterization of breakpoints involving pericentric inversions of human chromosome 9.

Pericentric inversions involving the secondary constriction (qh) region of chromosome 9 are considered to be normal variants. The evolutionary mechanisms and conservation of these inversions via Mendelian fashion have been investigated since the advent of banding techniques. Routine cytogenetic techniques cannot provide the fine characterization necessary to determine the type of genetic material involved in these rearrangements. Therefore, the fluorescence in situ hybridization technique with the human centromere-specific alpha satellite and the beta satellite (D9Z5) and classical satellite (D9Z1) human DNA probes were used to identify the breakpoints of chromosome 9 pericentric inversions. Four unique types of pericentric inversions involving the 9qh region were observed, and the mechanism may be due to breakage and reunion at the proposed breakpoints. They are: type A inversions consist of breakpoints within the alpha and beta satellite DNA regions; type B consist of breakpoints within the beta satellite DNA region and band 9q13; type C involve breakage within the beta and classical satellite DNA regions, and type D have breakpoints within the alpha and classical satellite DNA regions. Obviously, reshuffling of satellite DNA sequences has occurred, which has given rise to a variety of heteromorphisms whose clinical significance remains obscure.

Chromosome Breakage↗
PubMed1996

A new translocation, t(5;21)(q13;q22) in acute myelogenous leukemia.

We report a case of acute myelogenous leukemia with a variant translocation involving chromosomes 5 and 21 with breakpoints on 5q13 and 21q22 as revealed by various techniques including fluorescence in situ hybridization. The unusual presentation of t(5;21)(q13;q22), as the sole abnormality in acute myelogenous leukemia, is atypical.

Acute Disease↗
PubMed1996

Characterization of a complex translocation [t(4;9;22)(p16;q34;q11)] in chronic myelogenous leukemia by fluorescence in situ hybridization technique.

A patient was referred with a high leukocyte count and diagnosed with chronic myelogenous leukemia (CML). Although practically asymptomatic since the time of diagnosis, he had a variable and inconsistent response to treatment. All of his bone marrow cells had a complex, three-way translocation, involving chromosomes 4, 9 and 22. Translocation of chromosome 4 to chromosome 9 was undetectable by routine cytogenetic techniques; however, by the fluorescence in situ hybridization technique, a three-way translocation was identified, 46,XY,t(4;9;22)(p16;q34;q11). Although, other chromosomes are frequently involved in complex or variant translocations with chromosome 9 and 22, participation of chromosome 4 is a very rare event. So far, two previous cases have been described in the literature with translocations involving chromosome 4p16. We present a third case of CML having similar break points whose clinical presentation is unusual.

Allopurinol↗