Novel regions of allelic deletion on chromosome 18p in tumors of the lung, brain and breast.
(1/992)
Lung cancer is now the number one cause of cancer death for both men and women. An age-adjusted analysis over the past 25 years shows that in women specifically, lung cancer incidence is on the rise. It is estimated that 10-20 genetic events including the alteration of oncogenes and tumor suppressor genes will have occurred by the time a lung tumor becomes clinically evident. In an effort to identify regions containing novel cancer genes, chromosome 18p11, a band not previously implicated in disease, was examined for loss of heterozygosity (LOH). In this study, 50 matched normal and NSCLC tumor samples were examined using six 18p11 and one 18q12.3 PCR-based polymorphic markers. In addition, LOH was examined in 29 glioblastoma pairs and 14 paired breast carcinomas. This analysis has revealed potentially two regions of LOH in 18p11 in up to 38% of the tumor samples examined. The regions of LOH identified included a 2 cm area between markers D18S59 and D18S476, and a more proximal, 25 cm region of intermediate frequency between D18S452 and D18S453. These results provide evidence for the presence of one or more potential tumor suppressor genes on the short arm of chromosome 18 which may be involved in NSCLC, brain tumors and possibly breast carcinomas as well. (+info)
Insulin dependent diabetes mellitus (IDDM) and autoimmune thyroiditis in a boy with a ring chromosome 18: additional evidence of autoimmunity or IDDM gene(s) on chromosome 18.
(2/992)
A 4 year 3 month old boy with insulin dependent diabetes mellitus (IDDM), autoimmune thyroiditis, slight mental retardation, facial dysmorphism, and a de novo ring chromosome 18 (deletion 18q22.3-18qter) is described. This unique association of defects could represent a chance association. Alternatively, the clinical features could be the result of the chromosomal aberration. If so, one could speculate that a gene or genes on chromosome 18 might act as a suppressor or activator of the autoimmune process by itself or in concert with other IDDM loci. (+info)
Loss of heterozygosity at 18q21 is indicative of recurrence and therefore poor prognosis in a subset of colorectal cancers.
(3/992)
Adjuvant therapies are increasingly used in colorectal cancers for the prevention of recurrence. These therapies have side-effects and should, thus, be used only if really beneficial. However, the development of recurrence cannot be predicted reliably at the moment of diagnosis, and targeting of adjuvant therapies is thus based only on the primary stage of the cancer. Loss of heterozygosity (LOH) in the long arm of chromosome 18 is suggested to be related to poor survival and possibly to the development of metastases. We studied the value of LOH at 18q21 as a marker of colorectal cancer prognosis, association with clinicopathological variables, tumour recurrence and survival of the patients. Of the 255 patients studied, 195 were informative as regards LOH status when analysed in primary colorectal cancer specimens using the polymerase chain reaction (PCR) and fragment analysis. LOH at 18q21 was significantly associated with the development of recurrence (P = 0.01) and indicated poor survival in patients of Dukes' classes B and C, in which most recurrences (82%) occurred. An increased rate of tumour recurrence is the reason for poor survival among patients with LOH at 18q21 in primary cancer. These patients are a possible target group for recurrence-preventing adjuvant therapies. (+info)
An integrated map of chromosome 18 CAG trinucleotide repeat loci.
(4/992)
Expansions of trinucleotide CAG repeats have been demonstrated in at least eight neurodegenerative disorders, and suggested to occur in several others, including bipolar disorder and schizophrenia. Chromosome 18 loci have been implicated in bipolar disorder pedigrees by linkage analysis. To address this putative link between chromosome 18 CAG trinucleotide repeats and neuropsychiatric illness, we have screened a chromosome 18 cosmid library (LL18NCO2" AD") and identified 14 novel candidate loci. Characterisation of these loci involved repeat flank sequencing, estimation of polymorphism frequency and mapping using FISH as well as radiation hybrid panels. These mapped trinucleotide loci will be useful in the investigation of chromosome 18 in neurodegenerative or psychiatric conditions, and will serve to integrate physical and radiation hybrid maps of chromosome 18. (+info)
Detection of t(14;18) carrying cells in bone marrow and peripheral blood from patients affected by non-lymphoid diseases.
(5/992)
AIMS/BACKGROUND: To assess the presence of bcl-2/JH rearrangements in bone marrow and peripheral blood lymphocytes from patients affected by diseases other than malignant lymphomas. The t(14;18) (q32;q21) translocation, which juxtaposes the bcl-2 oncogene on chromosome 18 and the JH segment of the immunoglobulin heavy chain (IgH) genes on chromosome 14, is found frequently in follicular lymphomas. METHODS: A sensitive semi-nested polymerase chain reaction (PCR) was used to detect t(14;18) translocation in bone marrow aspirates and peripheral blood lymphocytes from 48 patients. In 137 additional individuals peripheral blood lymphocytes only were tested. RESULTS: Cells carrying bcl-2/JH rearrangements were detected in about a quarter of the bone marrow samples and half of the peripheral blood lymphocyte samples. In seven patients, t(14;18) positive cells were found in both the bone marrow and peripheral blood lymphocyte samples. The size of the PCR products and bcl-2/JH DNA sequence analysis showed that the same t(14;18) carrying clone was present in the bone marrow and the corresponding peripheral blood lymphocyte samples in three of these seven patients. Some patients had more than one bcl-2/JH rearrangement. There was no significant correlation between age and the translocation incidence. Cells carrying the t(14;18) translocation were present in peripheral blood lymphocyte samples with a similar incidence--between 47% and 52% in all age groups from 20 to 79 years. Patients older than 80 years had a lower (37%) but not significantly different incidence. CONCLUSIONS: These findings suggest that patients affected by non-lymphoid diseases may have several t(14;18) carrying cells and some of them undergo a clonal expansion. Whether individuals with t(14;18) positive cells are at a higher risk of lymphoid malignancies remains unanswered and further epidemiological studies are required. (+info)
Asynchronous replication of alleles in genomes carrying an extra autosome.
(6/992)
Transcriptional activity of genes appears to be highly related to their replication timing; alleles showing the common biallelic mode of expression replicate highly synchronously, whereas those with a monoallelic mode of expression replicate asynchronously. Here we used FISH to determine the level of synchronisation in replication timing of alleles in amniotic fluid cells derived from normal foetuses and from those with either of the trisomies for autosomes 21, 18 or 13, or for sex chromosomes (47,XXX and 47,XXY). Two pairs of alleles, not associated with the extra chromosome, were studied in subjects with each trisomy and three in normal subjects. In cells derived from normal foetuses and from foetuses with sex chromosome trisomies, each pair of alleles replicated synchronously; yet these very same alleles replicated asynchronously in cells derived from foetuses with trisomy for any of the three autosomes studied. The results suggest that the gross phenotypic abnormalities associated with an extra autosome are brought about not only by over-expression of genes present in three doses, but also by modifications in the expression of genes present in the normal two doses. (+info)
Correlation of bcl-2 rearrangement with clinical characteristics and outcome in indolent follicular lymphoma.
(7/992)
The t(14;18) translocation, which involves the bcl-2 oncogene, occurs in follicular lymphomas (FL) at two common sites: the major breakpoint region (MBR) and the minor cluster region (mcr). The biological and clinical significance of these breakpoints is unknown. The bcl-2 breakpoint site was determined in 247 previously untreated patients (49% men; median age 52 years) with indolent FL (155 grade I, 83 grade II, and 8 grade III) to correlate it with pretreatment characteristics, response, and outcome. The bcl-2 breakpoint site was determined by a polymerase chain reaction method of peripheral blood (all cases), bone marrows (149 cases), and fresh lymph node biopsy specimens (68 cases). The breakpoint site occurred at MBR in 175 cases (71%) and at mcr in 27 (11%). In 45 cases (18%), no breakpoint was detected (germline). No significant relationship was found between the rearrangements and the expression of BLC-2 and BAX proteins. Patients' germline for MBR and mcr tended to present more frequently with stage IV disease and higher beta2-microglobulin (beta2M) levels, whereas mcr-rearranged patients presented more frequently with early stage and normal beta2M. The complete response rate of germline patients was significantly lower than that of MBR and mcr patients. An estimated 3-year failure-free survival (FFS) for mcr, MBR, and germline cases was 95%, 76%, and 57%, respectively (P <.001). The bcl-2 breakpoint site was independent of serum beta2M and lactate dehydrogenase in its correlation with FFS. In conclusion, the bcl-2 rearrangement site is an important prognostic factor in indolent FL, useful to identify patients who may require different treatment. (+info)
Lymphatic vessel hypoplasia in fetuses with Turner syndrome.
(8/992)
Turner syndrome is associated with subcutaneous accumulation of fluid in the neck region that can be visualized sonographically from 10-14 weeks of gestation as massively increased nuchal translucency thickness. Possible mechanisms for this increased translucency include dilatation of the jugular lymphatic sacs because of developmental delay in the connection with the venous system, or a primary abnormal dilatation or proliferation of the lymphatic channels interfering with a normal flow between the lymphatic and venous systems. The aim of this study was to investigate the distribution of lymphatic vessels in nuchal skin tissue from fetuses with Turner syndrome compared with fetuses carrying trisomies 21, 18 and 13 and chromosomally normal controls. The distribution of vessels was examined by immunohistochemistry using a monoclonal antibody, PTN63, against 5' nucleotidase and an anti-laminin antibody. In normal control fetuses (n = 6) and those with trisomies 21 (n = 3), 18 (n = 2) and 13 (n = 2), PTN63-positive and laminin-positive vessels were evenly distributed throughout the dermis and subcutis. In Turner syndrome (n = 3), there was a chain of large vessels that stained with both PTN63 and laminin at the border between dermis and subcutis, but there was scarcity of vessels in the upper dermis and the subcutis. Using PTN63 alone, there were no positive vessels in the upper dermis. We conclude that in Turner syndrome lymphatic vessels in the upper dermis are hypoplastic. (+info)