A primary linkage map of the human chromosome 11q22-23 region

Genetic haplotyping of ataxia-telangiectasia families localizes the major gene to an approximately 850 kb region on chromosome 11q23.1

The genotyping data given localize the major A-T gene to an approximately 850 kb region. They also localize the group A A-T gene (ATA) to a region that contains the approximately 850 kb region. They are compatible with linking A-TFresno to 11q22-23. NBS-V2 does not link to this region. Four non-linking families contain only single affecteds, suggesting that these may be spontaneous mutations rather than evidence for an A-T gene outside the 11q22-23 region. Finally, two other non-linking families contain recombinant haplotypes that are compatible with a second A-T gene at 11q22-23, slightly distal to the approximately 850 kb region. However, convincing evidence for a second gene is still lacking.

Initial report of a genome search for the affective disorder predisposition gene in the old order Amish pedigrees: chromosomes 1 and 11

Family data have suggested that some forms of major affective disorder are genetic. Certain of the Old Order Amish pedigrees have a familial form of the disease. In this report we present the results of genetic analyses under autosomal dominant mode of transmission with reduced penetrance and three different disease hierarchies. The pedigrees were genotyped with 28 markers from chromosome 1 and 23 markers from chromosomes 11. None of the markers result in a significantly positive lod score.

In situ hybridisation analysis of a homogeneously staining region at 11q23-24 in an acute myeloid leukaemia (M5) using yeast artificial chromosomes

An example of a homogeneously staining region (hsr), occurring in an acute myeloid leukaemia (M5) on chromosome 11 in the region of bands q23-q24, has been analysed. In situ hybridisation using yeast artificial chromosome (YAC) DNA demonstrated that the amplification did not include the CD3 gene cluster and did not affect the human trithorax gene known to be disrupted by translocations at 11q23. In contrast, the amplification was shown to include the sequence D11S543 which has been previously mapped to chromosome band 11q24. High resolution analysis using confocal microscopy allowed the individual amplicons to be visualised, and it was shown that the hsr consisted of an 8-fold amplification of the region surrounding the probe D11S543. From previous estimates of human chromosome size it was possible to calculate that the hsr was composed of amplicons approximately 10 megabases in length. It was concluded that the region amplified did not extend as far as the translocation breakpoints occurring at 11q23 in acute leukaemias.

Atypical clinical presentation of ataxia telangiectasia

Ataxia telangiectasia (AT) is an autosomal recessive disorder characterized by progressive cerebellar ataxia, oculocutaneous telangiectasias, immunodeficiency with recurrent infections, IgA and IgE deficiency, and increased incidence of malignancies. The pathognomonic biological abnormalities consist of spontaneous chromosomal instability resulting in a high in vivo occurrence of cells with translocations, especially involving chromosomes 7 and 14, and a relative insensitivity of DNA replication in vitro to radiation exposure. We report on a patient with the biological hallmarks of AT but with atypical clinical manifestations. Although progressive cerebellar ataxia was present, the neurological picture was broader than that usually seen in AT and included peripheral polyneuropathy and spinal atrophy. On the other hand, telangiectasias, recurrent infections, malignancies, IgA deficiency, or other immunological abnormalities were not present. This illustrates that the clinical picture of AT is broad and nonspecific, and highlights the diagnostic value of cytogenetic analysis and studies of radioresistance of DNA synthesis.

11q deletions in human colorectal carcinomas: cytogenetics and restriction fragment length polymorphism analysis

Deletions and/or allelic losses of a portion of the long arm of chromosome 11 were discovered by cytogenetic and restriction fragment length polymorphism analyses in 23 of 39 (59%) informative cases of colorectal carcinoma. By comparing the patterns of loss of heterozygosity and chromosome rearrangements in different patients, we could map a common target region to 11q22-23. This region may contain a tumor suppressor gene, the inactivation of which may be involved in the development of tumors of the large intestine. The subgroup of malignancies with 11q alterations seemed to be enriched by tumors that were located in the rectum, that were Dukes' stage A, and that were well differentiated and mucin producing.

Molecular cloning and analysis of chromosome band 11q23 involved in leukaemia-associated translocations

Three overlapping yeast artificial chromosomes (YACs) spanning a 780 kb region of DNA around the CD3 locus on chromosome 11 have been isolated and characterised. The individual cloned regions have been mapped by in situ hybridisation to chromosome band 11q23, and a restriction enzyme map of this region has been constructed. The positions of these clones in relation to a series of leukaemia-associated chromosomal translocations has also been determined. It was concluded that, although two clones lay entirely proximal to the breakpoints examined, the third clone (13HH4) encompassed the breakpoints for the translocations t(4;11), t(6;11), and t(9;11). The t(9;11) was observed in an acute myeloid leukaemia in a patient previously treated for an unrelated malignancy. It would thus appear that the breakpoints at chromosome band 11q23 occurring in therapy-related leukaemias are in the same region as those found in adult and childhood acute leukaemias and may result from a common underlying mechanism.

Highly informative dinucleotide repeat polymorphism at the D11S29 locus on chromosome 11q23

The informativeness of locus D11S29 as a genetic marker was improved by the identification of a highly polymorphic (GT)n repeat within the locus. Ten alleles were identified in parents of 40 Centre d'Etude du Polymorphisme Humain families and the polymorphism information content (PIC) was 0.77. The increased PIC value thus enables refinement of the linkage map of 11q23.

Identification of a gene, MLL, that spans the breakpoint in 11q23 translocations associated with human leukemias

Recurring chromosomal translocations involving chromosome 11, band q23, have been observed in acute lymphoid leukemias and especially in acute myeloid leukemias. We recently showed that breakpoints in four 11q23 translocations, t(4;11)(q21;q23), t(6;11)(q27;q23), t(9;11)(p22;q23), and t(11;19)(q23;p13.3), were contained within a yeast artificial chromosome clone bearing the CD3D and CD3G gene loci. We have identified within the CD3 yeast artificial chromosome a transcription unit that spans the breakpoint junctions of the 4;11, 9;11, and 11;19 translocations, and we describe two other, related transcripts that are upregulated in the RS4;11 cell line. We have named this gene MLL (myeloid/lymphoid, or mixed-lineage, leukemia.

Genetic linkage analysis and homology relationships of genes located on human chromosome 11q

We have used DNA polymorphisms detected by probes for 11q to order 16 genes and to determine the genetic distances between them. Our map includes the genes for CD20, tyrosinase, progesterone receptor, stromelysin, collagenase, N-CAM, dopamine-D2 receptor, apolipoproteins AI-CIII-AIV, CD3-epsilon, -delta, and -gamma, porphobilinogen deaminase, thy-1, and ets-1. These genes have previously been sequenced as well as placed on the 11q cytogenetic map, which now makes them anchor points between the cytogenetic, genetic, and physical maps of this region. The ordering and distances between these genes are of immediate use in testing hypotheses of candidate genes for human genetic diseases associated with chromosome 11q. A comparison between our genetic map and similar maps from other species defines regions of homologous synteny that may be useful in mapping human genetic disease genes localized to the 11q region. Analysis of such homology provides additional bases for speculation of the evolutionary histories of gene families in this region.

The ATC (ataxia-telangiectasia complementation group C) locus localizes to 11q22-q23

The multisystem autosomal recessive disease ataxia-telangiectasia (A-T) is determined by several genes, as evidenced by the existence of four complementation groups in this disorder. Using linkage analysis, the ATA (A-T complementation group A) gene was previously localized to chromosome 11, region q22-q23. Analysis of the segregation of RFLP markers from this region in a Jewish-Moroccan family assigned to group C indicates that the ATC (A-T complementation group C) gene localizes to chromosome 11q22-q23 as well.

CD3G is within 200 kb of the leukemic t(4;11) translocation breakpoint

The t(4;11)(q21;q23) has been associated with acute lymphocytic leukemia (ALL) especially in infants. The t(4;11) breakpoint on chromosome 11 is cytogenetically indistinguishable from breakpoints for other leukemia-associated translocations affecting 11q23. The molecular basis of the t(4;11) is unknown although a number of genes have been mapped to 11q23. The CD3D, G, and E genes have been positioned proximal to the 11q23 breakpoint of the 4;11 translocation while the THY1 and ETS1 genes have been mapped distal to this breakpoint. We report evidence that CD3G is within 200 kb of the 4;11 breakpoint as observed by pulsed field gel analysis. A rearrangement of the CD3G gene has been observed in a cell line derived from a patient with the t(4;11) translocation and in a hybrid cell line containing the derivative 11q chromosome derived from this cell line, using the restriction enzymes SacII and ClaI. Similar rearrangements using SacII were observed in 2 further patients with ALL and the t(4;11) translocation. No rearrangements in the same DNA were observed using ETS1, THY1, and D11S29 and a range of rare cutter restriction enzymes. CD3G thus provides a tool for the cloning and analysis of the 4;11 translocation, and poses a question of its possible involvement at long range with this translocation.

Gene mapping by microdissection and enzymatic amplification: heterogeneity in leukaemia associated breakpoints on chromosome 11

A new strategy for mapping chromosome translocation breakpoints in relation to known genes has been developed. This approach is based on the amplification by the polymerase chain reaction (PCR) of specific target sequences from small numbers of microdissected chromosome fragments. This method has been applied to leukaemia-associated translocations affecting the q23 region of chromosome 11. In two independent leukaemias, the t(6;11) translocation was distinguished from the t(9;11) and t(4;11) translocations by demonstrating that the former breakpoint on chromosome 11 lay proximal to the CD3D gene while the latter breakpoints lay distal to CD3D. All three translocation breakpoints were found to lie proximal to ETSI and THYI. The data suggest that although these leukaemia-associated breakpoints on chromosome 11 are cytogenetically identical they may involve disruption of different genes. This approach offers a rapid alternative to mapping by hybridisation of probes either in situ to chromosomes or to somatic cell hybrids containing the appropriate derivative chromosomes.

A physical linkage group in human chromosome band 11q23 covering a region implicated in leukocyte neoplasia

Six genes on human chromosome band 11q23 have been linked by pulse-field gel electrophoretic analysis with the order cen-CD3E-CD3D-CD3G-PBGD-CBL2-THY1-qter. The corresponding long-range restriction map covers 1.8 Mb, the telomeric half of which (PBGD-CBL2-THY1) is localized to subband 11q23.3. Four genes (CD3E, CD3D, CD3G, and PBGD) can be positioned precisely, and with known transcriptional orientation, with respect to rare-cutter restriction sites. The linkage group covers a region implicated in leukocyte malignancy: several nonrandom neoplasia-associated translocation chromosomes have breakpoints which separate the CD3 genes from PBGD, CBL2, and THY1. Thus, we are able to localize such breakpoints, and consequently any affected candidate genes, to the 750 kb between CD3G and PBGD.

Mapping the human genome: current status

The human genome has already been the subject of extensive research activity even though the Human Genome Project is only just officially starting. This review and the accompanying wall chart attempt to provide an integrated, quantitative, and detailed summary of the status of knowledge on the human genome in mid-1990. The analysis has highlighted the rudimentary nature of many of the information links needed for the task. While this overview could not be fully comprehensive and required simplifying assumptions, the results have provided estimates of relative progress on a region-by-region basis throughout the genome.

Fine mapping of the chromosome 11q22-23 region using PFGE, linkage and haplotype analysis; localization of the gene for ataxia telangiectasia to a 5cM region flanked by NCAM/DRD2 and STMY/CJ52.75, phi 2.22

Using pulsed-field gel electrophoresis, and a range of different enzyme digests, we have established that both markers of each of the pairs CJ52.208/YNB3.12, NCAM/DRD2, and STMY/CJ52.75, on chromosome 11q22-23, show physical linkage on a single DNA fragment. We have also shown, using genetic linkage and haplotype analyses, that these markers lie within a region of approximately 18cM, which, it has been shown previously, is likely to contain the A-T gene. The relative positions of these marker loci, and the distance between them was determined in order to construct a detailed map which has allowed a more precise localization of the A-T gene. We have shown that in pairwise linkage analysis the strongest support for linkage to the A-T gene was with the STMY/CJ52.75 locus (Z = 5.59, theta = 0.0). A three-point analysis using the results from STMY/CJ52.75 and the closely linked marker phi 2.22 gave Z = 5.55, theta = 0.03. Despite persisting evidence of some linkage to Thy-1 our results are consistent with the existence of a single A-T locus on chromosome 11q22-23 and our best estimate of the position of this locus places it between NCAM/DRD2 and (STMY/CJ52.75, F2.22) (Z = 6.74), a region of approximately 5cM in males.