HRAS1-selected chromosome transfer generates markers that colocalize aniridia- and genitourinary dysplasia-associated translocation breakpoints and the Wilms tumor gene within band 11p13

A Number of the N-terminal RASSF Family: RASSF7

The Ras association domain family 7 (RASSF7, also named HRC1), a potential tumor-related gene, located on human chromosome 11p15, has been identified as an important member of the N-terminal RASSF family. Whereas, the molecular biological mechanisms of RASSF7 in tumorigenesis remain to be further established. We perform a systematic review of the literature and assessment from PUBMED and MEDLINE databases in this article. RASSF7 plays a significant role in mitosis, microtubule growth, apoptosis, proliferation and differentiation. Many research literature shows that the RASSF7 could promote the occurrence and advance of human tumors by regulating Aurora B, MKK4, MKK7, JNK, YAP, MEK, and ERK, whereas, it might inhibit c-Myc and thus lead to the suppression of tumorigenesis. The pregulation of RASSF7 often occurs in various malignancies such as lung cancer, neuroblastoma, thyroid neoplasm, hepatocellular cancer, breast cancer and gastric cancer. The expression stage of RASSF7 is positively correlated with the tumor TNM stage. In this review, we primarily elaborate on the acknowledged structure and progress in the various biomechanisms and research advances of RASSF7, especially the potential relevant signaling pathways. We hope that RASSF7 , a prospective therapeutic target for human malignancies, could play an available role in future anti-cancer treatment.

PAX6: 25th anniversary and more to learn

The DNA-binding transcription factor PAX6 was cloned 25 years ago by multiple teams pursuing identification of human and mouse eye disease causing genes, cloning vertebrate homologues of pattern-forming regulatory genes identified in Drosophila, or abundant eye-specific transcripts. Since its discovery in 1991, genetic, cellular, molecular and evolutionary studies on Pax6 mushroomed in the mid 1990s leading to the transformative thinking regarding the genetic program orchestrating both early and late stages of eye morphogenesis as well as the origin and evolution of diverse visual systems. Since Pax6 is also expressed outside of the eye, namely in the central nervous system and pancreas, a number of important insights into the development and function of these organs have been amassed. In most recent years, genome-wide technologies utilizing massively parallel DNA sequencing have begun to provide unbiased insights into the regulatory hierarchies of specification, determination and differentiation of ocular cells and neurogenesis in general. This review is focused on major advancements in studies on mammalian eye development driven by studies of Pax6 genes in model organisms and future challenges to harness the technology-driven opportunities to reconstruct, step-by-step, the transition from naïve ectoderm, neuroepithelium and periocular mesenchyme/neural crest cells into the three-dimensional architecture of the eye.

Regional mapping panels for chromosomes 3, 4, 5, 11, 15, 17, 18, and X

The NIGMS Human Genetic Mutant Cell Repository collects and distributes well-characterized human/rodent somatic cell hybrid regional mapping panels for human chromosomes 3, 4, 5, 11, 15, 17, 18, and X. Each regional mapping panel consists of 4 to 11 hybrids that divide the chromosome into 5 to 11 intervals. These panels have been extensively characterized by the submitters and the NIGMS Repository.

Genotype/phenotype correlations in Wilms' tumor

Study of genotype/phenotype relationships involving the Wilms' tumor (WT) gene, WT1, in WT patients has provided insights into the function of the WT1 protein, a transcriptional regulator, and has suggested possible mutational mechanisms important in the etiology of WT. For example, the identification of deletion/insertion mutations in the first exon implicates a deletion hotspot consensus sequence in the etiology of these mutations. The disproportionate number of WT/aniridia patients with such mutations further suggest that this genetic mechanism may be enhanced by the hemizygous state. WT1 mutations are observed throughout the gene and, as predicted by the two hit mutational model, germline mutations predominantly occur in patients with congenital genitourinary (GU) anomalies and/or bilateral disease. The presence of hemizygous mutations in tumors from individuals with germline 11p13 deletions encompassing WT1 supports the hypothesis that inactivation of both WT1 alleles is important in tumorigenesis. Analyses of WT1 mutations in individuals with WT-associated Drash syndrome and WT patients with GU anomalies in the absence of Drash syndrome indicate that Drash patients almost invariably carry germline missense mutations in the zinc finger domains whereas WT/GU patients carry germline mutations that delete the WT1 gene or encode truncated proteins. These data suggest a functional difference between mutant WT1 protein carrying a single amino acid substitution versus mutant WT1 protein that is grossly truncated or WT1 haploinsufficiency. These and other genotype/phenotype correlations in WT patients will be discussed in more detail.

Abnormal gonadal differentiation in two subjects with ambiguous genitalia, Mullerian structures, and normally developed testes: evidence for a defect in gonadal ridge development

Among a group of patients with abnormal sexual differentiation, we have identified two subjects who had a 46,XY karyotype, ambiguous genitalia, and well-developed Müllerian structures, but normal appearing testes. The presence of ambiguous genitalia and persistent Müllerian structures implied both Leydig cell and Sertoli cell dysfunction, hence, gonadal dysgenesis. However, the normal testicular histology suggested that the underlying abnormality was not a defect in testis determination itself but an abnormality in timing of gonadal ridge and testis development. In one of the two subjects genomic DNA was available. The sequence of the SRY gene was normal. Because rare patients with partial androgen insensitivity may have a similar phenotype, the AR gene was evaluated by denaturing gradient gel electrophoresis (DGGE) and was normal. Some subjects with mutation of the WT1 gene or with deletion of the distal short arm of chromosome 9 may have similar phenotypes. The WT1 gene was studied by single-strand conformation polymorphism (SSCP) analysis and was normal. In addition, there was no loss of heterozygosity of polymorphic markers in distal 9p. The gene for Müllerian inhibiting substance (MIS) was also studied by SSCP and was normal. Although the exact mechanism for the defect in the two subjects is unknown, it may be due to an abnormality in a gene or genes involved in the timing of gonadal ridge development.

The molecular genetics of Wilms tumor: a paradigm of heterogeneity in tumor development

The evidence that genes on chromosome 11 are involved in Wilms tumor development is convincing; however, it is also evident that the mechanisms of tumorigenesis are more complex than the two-mutation model originally proposed. Potentially several genetic loci participate in Wilms tumor development. This should not be too surprising considering the complexity of pathways regulating growth and differentiation in nephrogenesis. It is possible that these various genes act at different points in the differentiation pathway and disruption of their normal function contributes to tumorigenesis. In fact, these loci may interact with one another in tumor formation. Certain types of genetic alterations may be the rate-limiting steps, but other changes may also contribute or be necessary for tumor development. Homozygous inactivation of specific genes, combinations of mutated alleles, and relaxation of genetic imprinting, or even interactions between different mutated alleles may all be part of the process for individual tumors. It has been found that some patients with the WAGR syndrome who are hemizygous for WT1 at 11p13 have in addition loss of heterozygosity within 11p15, and a sporadic tumor has been shown to have a WT1 mutation and loss of heterozygosity at loci at both 11p15 and 11p13 (59,85). These observations suggest the potential for interaction among the various Wilms tumor loci. Not only are there likely to be a number of different genetic loci linked to Wilms tumor development, but the mechanisms underlying altered gene function may be more variable than originally believed. It is probably not correct to think of Wilms tumor as a homogeneous entity. Mutations at different loci or various combinations of genetic lesions could well be responsible for the different categories of Wilms tumors. This apparent genetic complexity of Wilms tumor development is a concept that can very likely be applied to many other types of neoplasms. A complete understanding of Wilms tumorigenesis awaits identification of all members of the Wilms tumor gene family and the functional significance of their alterations.

Molecular genetic aspects of human cancers: the 1993 Frank Rose Lecture

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Schizophrenia-associated chromosome 11q21 translocation: identification of flanking markers and development of chromosome 11q fragment hybrids as cloning and mapping resources

Genetic linkage, molecular analysis, and in situ hybridization have identified TYR and D11S388 as markers flanking the chromosome 11 breakpoint in a large pedigree where a balanced translocation, t(1;11)(q43;q21), segregates with schizophrenia and related affective disorders. Somatic cell hybrids, separating the two translocation chromosomes from each other and from the normal homologues, have been produced with the aid of immunomagnetic sorting for chromosome 1- and chromosome 11-encoded cell-surface antigens. The genes for two of these antigens map on either side of the 11q breakpoint. Immunomagnetic bead sorting was also used to isolate two stable X-irradiation hybrids for each cell-surface antigen. Each hybrid carries only chromosome 11 fragments. Translocation and X-irradiation hybrids were analyzed, mainly by PCR, for the presence of 19 chromosome 11 and 4 chromosome 1 markers. Ten newly designed primers are reported. The X-irradiation hybrids were also studied cytogenetically, for human DNA content, by in situ Cot1 DNA hybridization and by painting the Alu-PCR products from these four lines back onto normal human metaphases. The generation of the translocation hybrids and of the chromosome 11q fragment hybrids is a necessary preliminary to determining whether a schizophrenia-predisposition gene SCZD2 is encoded at this site.

Submicroscopic deletions at the WAGR locus, revealed by nonradioactive in situ hybridization

Fluorescence in situ hybridization (FISH) with biotin-labeled probes mapping to 11p13 has been used for the molecular analysis of deletions of the WAGR (Wilms tumor, aniridia, genitourinary abnormalities, and mental retardation) locus. We have detected a submicroscopic 11p13 deletion in a child with inherited aniridia who subsequently presented with Wilms tumor in a horseshoe kidney, only revealed at surgery. The mother, who has aniridia, was also found to carry a deletion including both the aniridia candidate gene (AN2) and the Wilms tumor predisposition gene (WT1). This is therefore a rare case of an inherited WAGR deletion. Wilms tumor has so far only been associated with sporadic de novo aniridia cases. We have shown that a cosmid probe for a candidate aniridia gene, homologous to the mouse Pax-6 gene, is deleted in cell lines from aniridia patients with previously characterized deletions at 11p13, while another cosmid marker mapping between two aniridia-associated translocation breakpoints (and hence a second candidate marker) is present on both chromosomes. These results support the Pax-6 homologue as a strong candidate for the AN2 gene. FISH with cosmid probes has proved to be a fast and reliable technique for the molecular analysis of deletions. It can be used with limited amounts of material and has strong potential for clinical applications.

Human RAG2, like RAG1, is on chromosome 11 band p13 and therefore not linked to ataxia telangiectasia complementation groups

Ataxia telangiectasia (A-T) is an inherited, recessive, cancer-prone disease with associated immunodeficiency and chromosome abnormalities involving TCR loci. The latter phenomena implicate errors of the enzyme(s) responsible for assembly of antigen receptor genes (recombinase) in disease pathogenesis. Here we report the location of a human recombination activating gene (RAG2), in addition to RAG1, on chromosome 11, band p13, thereby formally demonstrating linkage of these genes in humans and showing that they are not linked to the known locus responsible for the A-T syndrome.

Evidence for WT1 as a Wilms tumor (WT) gene: intragenic germinal deletion in bilateral WT

The inactivation of two alleles at a locus on the short arm of chromosome 11 (band 11p13) has been suggested to be critical steps in the development of Wilms tumor (WT), a childhood kidney tumor. Two similar candidate WT cDNA clones (WT33 and LK15) have recently been identified on the basis of both their expression in fetal kidney and their location within the smallest region of overlap of somatic 11p13 deletions in some tumors. These homozygous deletions, however, are large and potentially affect more than one gene. Using a cDNA probe to the candidate gene, we have analyzed DNA from both normal and tumor tissue from WT patients, in an effort to detect rearrangements at this locus. We report here a patient with bilateral WT who is heterozygous for a small (less than 11 kb) germinal deletion within this candidate gene. DNA from both tumors is homozygous for this intragenic deletion allele, which, by RNA-PRC sequence analysis, is predicted to encode a protein truncated by 180 amino acids. These data support the identification of this locus as an 11p13 WT gene (WT1) and provide direct molecular data supporting the two-hit mutational model for WT.

Direct pulsed field gel electrophoresis of Wilms' tumors shows that DNA deletions in 11p13 are rare

In order to search for small tumor-specific deletions in 11p13 we analysed DNA isolated from 30 fresh Wilms' tumor (WT) samples with pulsed field gel electrophoresis. For these studies we have isolated new probes from the ends of several Notl fragments. Using these and previously described probes from 11p13 we first completed and extended the existing map of the 11p13 region. The analysis of the tumor material showed that (I) tumor-specific deletions were very rare: one homozygous deletion out of 30 tumors analysed, (2) hemizygous deletions were not observed in any of the tumors. The homozygous deletion in one patient spans 220 kb and is composed of a tumor-specific translocation associated with a deletion on one chromosome and a deletion of about 220 kb on the other chromosome at the same site. The WT-33 Wilms' tumor candidate gene maps to this deleted segment. A small constitutional deletion of 1,300 kb was identified in a patient with WT and genital tract malformations. These results suggest that in the majority of sporadic WT loss of gene function is due to subtle alterations in the gene, e.g., point mutations or very small deletions.

Molecular analysis of chromosome region 11p13 in patients with Drash syndrome

The association of nephropathy, Wilms' tumour and genital abnormalities is known as Drash syndrome. Two of these features are also seen in the WAGR (Wilms' tumour, aniridia, genito-urinary abnormalities, mental retardation) complex, known to be associated with deletions of chromosome region 11p13. We have carried out karyotypic and molecular studies in 10 Drash patients, 5 males and 5 females. All the males had a 46XY karyotype as did 3/5 of the phenotypic females, the other two having a 46XX karyotype. One of the 46XX females also had a deletion of region 11p13-p12, the only detectable autosomal chromosome abnormality in any of the patients studied. Lymphoblastoid cell lines were prepared from 6 of the Drash patients and were used in dosage studies using a variety of DNA probes from the 11p13 region. There was no evidence of microdeletions in any patient with a normal karyotype. Because of the 46XY karyotype in phenotypic females, selected X and Y chromosome loci were analysed and all found to be normal. Although Drash syndrome is likely to be of genetic origin, there are no readily detected deletions within the 11p13 region.

The human MyoD1 (MYF3) gene maps on the short arm of chromosome 11 but is not associated with the WAGR locus or the region for the Beckwith-Wiedemann syndrome

The human gene encoding the myogenic determination factor myf3 (mouse MyoD1) has been mapped to the short arm of chromosome 11. Analysis of several somatic cell hybrids containing various derivatives with deletions or translocations revealed that the human MyoD (MYF3) gene is not associated with the WAGR locus at chromosomal band 11p13 nor with the loss of the heterozygosity region at 11p15.5 related to the Beckwith-Wiedemann syndrome. Subregional mapping by in situ hybridization with an myf3 specific probe shows that the gene resides at the chromosomal band 11p14, possibly at 11p14.3.

Somatic cell hybrid and long-range physical mapping of 11p13 microdissected genomic clones

Microdissection and microcloning of banded human metaphase chromosomes have been used to construct a genomic library of 20,000 clones that is highly enriched for chromosome 11p13 DNA sequences. Clones from this library have been mapped on a panel of human-rodent somatic cell hybrids that divides the region from distal p12 to proximal p14 into seven physical intervals, A total of 1500 clones has been isolated, 250 clones have been characterized, and 58 clones have been mapped. Six of the clones were used to complete a long-range physical map of 7.5 megabases through the region. Two of the clones are localized to the Wilms tumor (WT) region, three are localized to the aniridia (AN2) region, and two are localized to the region between WT and AN2. The library represents DNA sequences spanning a distance of approximately 13 x 10(6) base pairs, with an average density of one clone per 37,000 base pairs.

Role for the Wilms tumor gene in genital development?

Detailed molecular definition of the WAGR region at chromosome 11p13 has been achieved by chromosome breakpoint analysis and long-range restriction mapping. Here we describe the molecular detection of a cytogenetically invisible 1-megabase deletion in an individual with aniridia, cryptorchidism, and hypospadias but no Wilms tumor (WT). The region of overlap between this deletion and one associated with WT and similar genital anomalies but no aniridia covers a region of 350-400 kilobases, which is coincident with the extent of homozygous deletion detected in tumor tissue from a sporadic WT. A candidate WT gene located within this region has recently been isolated, suggesting nonpenetrance for tumor expression in the first individual. The inclusion within the overlap region of a gene for WT predisposition and a gene for the best-documented WT-associated genitourinary malformations leads us to suggest that both of these anomalies result from a loss-of-function mutation at the same locus. This in turn implies that the WT gene exerts pleiotropic effect on both kidney and genitourinary development, a possibility supported by the observed expression pattern of the WT candidate gene in developing kidney and gonads.

Isolation and regional localisation of DNA sequences from a human chromosome 11-specific cosmid library

A cosmid library has been prepared in the lorist-B vector from a mouse/human somatic cell hybrid containing region 11q23-11pter as the only human component. This chromosome region is stably maintained in the hybrid as a result of translocation onto one copy of mouse chromosome 13. Individual cosmids containing human DNA were isolated by their ability to hybridise with total human DNA, digested with either HindIII or EcoRI, and 33 individual unique sequences were identified. These fragments were then isolated and subcloned into the bluescribe plasmid vector. Regional localisation of these unique sequences was achieved using a panel of somatic cell hybrids containing different overlapping deletions of chromosome 11. The majority of the 33 mapped sequences derived from the long arm of chromosome 11. Two clones were located within the 11p13-p14 region, which is associated with a predisposition to Wilms' tumour. These probes supplement those already mapped to this chromosome and will assist in the generation of a detailed chromosome 11 linkage map.

Rhabdomyosarcoma-associated locus and MYOD1 are syntenic but separate loci on the short arm of human chromosome 11

The MYOD1 locus is preferentially expressed in skeletal muscle and at higher levels in its related neoplasm, rhabdomyosarcoma. We have combined physical mapping of the human locus with meiotic and physical mapping in the mouse, together with synteny homologies between the two species, to compare the physical relationship between MYOD1 and the genetically ascertained human rhabdomyosarcoma-associated locus. We have determined that the myogenic differentiation gene is tightly linked to the structural gene for the M (muscle) subunit of lactate dehydrogenase in band p15.4 on human chromosome 11 and close to the p and Ldh-1 loci in the homologous region of mouse chromosome 7. Because the rhabdomyosarcoma locus maps to 11p15.5, MYOD1 is very unlikely to be the primary site of alteration in these tumors. Further, these analyses identify two syntenic clusters of muscle-associated genes on the short arm of human chromosome 11, one in the region of rhabdomyosarcoma locus that includes IGF2 and TH and the second the tightly linked MYOD1 and LDHA loci, which have been evolutionarily conserved in homologous regions of both the mouse and the rat genomes.

Homozygous deletion in Wilms tumours of a zinc-finger gene identified by chromosome jumping

Cytogenetic analysis has identified chromosome 11p13 as the smallest overlap region for deletions found in individuals with WAGR syndrome, which includes Wilms tumour (a recessive childhood nephroblastoma), aniridia, genito-urinary abnormalities and mental retardation. The underlying loci have since been resolved into an aniridia (AN2) locus at a telomeric position, and a locus of closely spaced genes or a single pleiotropic gene involved in genito-urinary tract abnormalities and Wilms tumour at a more centromeric position. Pulsed-field gel analysis of the 11p13 region has revealed the presence of several putative CpG islands, structures which are frequently associated with the 5' ends of expressed sequences, mainly housekeeping genes and some tissue-specific genes. Starting from a CpG island, we have now isolated four neighbouring CpG islands, all within 650 kilobases (kb), by means of two consecutive bidirectional jumps in rare-cutting restriction-enzyme jumping libraries. In two instances, flanking sequences were conserved in other species and RNA transcripts were identified. A complementary DNA clone isolated for one of them derives from an RNA highly expressed in fetal kidney, and is predicted to encode a Krüppel-like zinc-finger protein that is probably a transcription factor. The entire cDNA region is included in two partially overlapping homozygous deletions found in Wilms tumour DNA samples. Cloning of the breakpoints in one tumour revealed a deletion size of 170 kb, one-third of which is covered by the cDNA. The expression pattern and sequence of this cDNA could point to an important role for its corresponding gene in the normal development of the renal system as well as in Wilms tumour.

SV40-mediated tumor selection and chromosome transfer to enrich for cystic fibrosis region

The somatic cell hybrid C121, with chromosome 7 as its sole human component, arose when mouse macrophages SV40 genomes are integrated at 7q31-7q35. We show that hybrids with a reduced chromosome 7 component, but which retain markers linked to the cystic fibrosis locus, can be generated by direct in vivo tumor selection or following chromosome-mediated gene transfer and SV40-mediated cellular transformation. Our methods for chromosome fragmentation and fine-structure mapping can now be applied to the substantial number of SV40-transformed human cell lines, with independent chromosomal integration sites, already available. Our results also suggest that expression of human epidermal growth factor receptor augments the tumorigenic potential of the SV40-transformed C121 hybrid.

Aniridia, Wilms' tumor and human chromosome 11

Aniridia-a developmental abnormality of the eye in which the iris is apparently absent-has been shown to be genetically associated with Wilms' tumor (an embryonic nephroblastoma) in the WAGR syndrome. Genetic and cytogenetic evidence points to band p13 of human chromosome 11 as the localization of the genes responsible for these defects. Deleted chromosomes 11 from WAGR patients and clinically associated translocations involving 11p13 have been used to map and order genes and anonymous DNA markers around the WAGR locus refining the localization of the aniridia and Wilms' tumor genes to within about 1 million base pairs of DNA.

A fine-structure deletion map of human chromosome 11p: analysis of J1 series hybrids

Deletion analysis offers a powerful alternative to linkage and karyotypic approaches for human chromosome mapping. A panel of deletion hybrids has been derived by mutagenizing J1, a hamster cell line that stably retains chromosome 11 as its only human DNA, and selecting for loss of MIC1, a surface antigen encoded by a gene in band 11p13. A unique, self-consistent map was constructed by analyzing the pattern of marker segregation in 22 derivative cells lines; these carry overlapping deletions of 11p13, but selectively retain a segment near the 11p telomere. The map orders 35 breakpoints and 36 genetic markers, including 3 antigens, 2 isozymes, 12 cloned genes, and 19 anonymous DNA probes. The deletions span the entire short arm, dividing it into more than 20 segments and define a set of reagents that can be used to rapidly locate any newly identified marker on 11p, with greatest resolution in the region surrounding MIC1. The approach we demonstrate can be applied to map any mammalian chromosome. To test the gene order, we examined somatic cell hybrids from five patients, whose reciprocal translocations bisect band 11p13; these include two translocations associated with familial aniridia and two with acute T-cell leukemia. In each patient, the markers segregate in telomeric and centromeric groups as predicted by the deletion map. These data locate the aniridia gene (AN2) and a recurrent T-cell leukemia breakpoint (TCL2) in the marker sequence, on opposite sides of MIC1. To provide additional support, we have characterized the dosage of DNA markers in a patient with Beckwith-Wiedemann syndrome and an 11p15-11pter duplication. Our findings suggest the following gene order: TEL - (HRAS1, MER2, CTSD, TH/INS/IGF2, H19, D11S32) - (RRM1, D11S1, D11S25, D11S26) - D11S12 - (HBBC, D11S30) - D11S20 - (PTH, CALC) - (LDHA, SAA, TRPH, D11S18, D11S21) - D11S31 - D11S17 - HBVS1 - (FSHB, D11S16) - AN2 - MIC1 - TCL2 - delta J - CAT - MIC4 - D11S9 - D11S14 - ACP2 - (D11S33, 14L) - CEN. We have used the deletion map to show the distribution on 11p of two centromeric repetitive elements and the low-order interspersed repeat A36Fc. Finally, we provide evidence for an allelic segregation event in the hamster genome that underlies the stability of chromosome 11 in J1. The deletion map provides a basis to position hereditary disease loci on 11p, to distinguish the pattern of recessive mutations in different forms of cancer and, since many of these genes have been mapped in other mammalian species, to study the evolution of a conserved syntenic group.

Long-range restriction map around 11p13 aniridia locus

Using two random DNA markers, and pulsed field gel electrophoresis, a 1.5-Mb physical map surrounding the 11p13 aniridia locus (AN2) has been assembled. The map was constructed using a combination of single- and double-restriction digests on DNA from normal controls and a patient transmitting familial aniridia. The aniridia patient has a chromosome translocation and the two DNA markers flank the breakpoint. This 11p13 breakpoint lies no further than 100 kb from the DNA marker 1104 (D11S95), located on the centromeric side of the breakpoint. Two CpG islands, separated by 550 kb and flanking the translocation, suggest an upper limit to the size of the gene.

Loss of chromosome 11p alleles in cultured cells derived from Wilms' tumours

Cell cultures have been produced from five Wilms' tumours. All cultures had a finite lifespan and a pattern of antigen expression which indicated that the cells were derived from the differentiated components of the tumours. No cells showed any of the expected characteristics of the putative Wilms' tumour stem cell. Nevertheless, in both cases where the original tumours showed a loss of heterozygosity at chromosome 11p alleles, the cultured cells also demonstrated a loss of heterozygosity. Thus these cell cultures definitely originated from Wilms' tumour tissue. The results demonstrate that cell cultures can be produced from the differentiated tissues present in Wilms' tumours and that these non-immortal cells show no 'transformed' phenotype, even though they possess the genetic changes present in the original tumour.

Cloning of breakpoints of a chromosome translocation identifies the AN2 locus

Chromosome translocations involving 11p13 have been associated with familial aniridia in two kindreds highlighting the chromosomal localization of the AN2 locus. This locus is also part of the WAGR complex (Wilms tumor, aniridia, genitourinary abnormalities, and mental retardation). In one kindred, the translocation is associated with a deletion, and probes for this region were used to identify and clone the breakpoints of the translocation in the second kindred. Comparison of phage restriction maps exclude the presence of any sizable deletion in this case. Sequences at the chromosome 11 breakpoint are conserved in multiple species, suggesting that the translocation falls within the AN2 gene.

Characterization of a panel of somatic cell hybrids for subregional mapping along 11p and within band 11p13. Subdivision of the WAGR complex region

The short arm of chromosome 11 carries genes involved in malformation syndromes, including the aniridia/genitourinary abnormalities/mental retardation (WAGR) syndrome and the Beckwith-Wiedemann syndrome, both of which are associated with an increased risk of childhood malignancy. Evidence comes from constitutional chromosomal aberrations and from losses of heterozygosity, limited to tumor cells, involving regions 11p13 and 11p15. In order to map the genes involved more precisely, we have fused a mouse cell line with cell lines from patients with constitutional deletions or translocations. Characterization of somatic cell hybrids with 11p-specific DNA markers has allowed us to subdivide the short arm into 11 subregions, 7 of which belong to band 11p13. We have thus defined the smallest region of overlap for the Wilms' tumor locus bracketed by the closest proximal and distal breakpoints in two of these hybrids. The region associated with the Beckwith-Wiedemann syndrome spans the region flanked by two 11p15.5 markers, HRAS1 and HBB. These hybrids also represent useful tools for mapping new markers to this region of the human genome.

Long-range structure of H-ras 1-selected transgenomes

We have used chromosome-mediated gene transfer (CMGT) and whole cell fusion to derive human-mouse hybrid cells carrying reduced human chromosomes 11, by selecting for expression of the transforming H-ras 1 oncogene. To realize the full potential of these somatic cell genetic techniques as resources for enriched DNA probe isolation and the fine structure mapping of chromosomes, the nature of any molecular rearrangements that may accompany the process of DNA transfer must be understood. We have analyzed the long-range structure of our transgenomes by pulsed field gel electrophoresis (PFGE) and show here that, whereas during cell fusion several megabase pairs (Mb) of DNA can be transferred intact, multiple rearrangements of DNA accompany CMGT even in transgenomes where other methods of analysis gave no indication of such molecular scrambling.

The aniridia-Wilms' tumour association: molecular and genetic analysis of chromosome deletions on the short arm of chromosome 11

We have analysed karyotypes and DNA from three patients with aniridia (congenital absence of irises) and Wilms' tumour. All three had constitutional deletions from the short arm of chromosome 11. The minimum region of overlap of the deletion involves a small region of band 11p13 presumed to contain the genetic loci responsible for both phenotypic abnormalities. Using cells from these patients, somatic cell hybrids with transformed mouse cells have been prepared. Individual subclones retaining either the deletion-11 chromosome or the normal chromosome 11, in addition to a variety of other human chromosomes, have been identified. The relative position of these breakpoints have been determined and the panel of hybrids has been used to map randomly-isolated 11p13 DNA sequences. The characterisation of these deletions has provided a useful panel of hybrids for random mapping strategies designed to identify the Wilms' and aniridia genes.

A deletion map of the WAGR region on chromosome 11

The WAGR (Wilms tumor, aniridia, genitourinary anomalies, and mental retardation) region has been assigned to chromosome 11p13 on the basis of overlapping constitutional deletions found in affected individuals. We have utilized 31 DNA probes which map to the WAGR deletion region, together with six reference loci and 13 WAGR-related deletions, to subdivide this area into 16 intervals. Specific intervals have been correlated with phenotypic features, leading to the identification of individual subregions for the aniridia and Wilms tumor loci. Delineation, by specific probes, of multiple intervals above and below the critical region and of five intervals within the overlap area provides a framework map for molecular characterization of WAGR gene loci and of deletion boundary regions.

Rapid isolation of moderate and highly polymorphic DNA fragments mapping close to WT (Wilms' tumour) and AN2 (aniridia) on chromosome 11

Genes implicated in the development of Wilms' tumour (WT) and aniridia (AN2) have been localised to a sub-region of band p13 on chromosome 11 by molecular and cytogenetic characterisation of WAGR syndrome patients carrying variable constitutional deletions. Polymorphic markers for the region would be valuable for linkage analysis in the familial forms of both Wilms' tumour and aniridia, as well as for studying somatic rearrangements of chromosome 11 in a variety of tumour types. Here we describe the isolation and characterisation of three frequently polymorphic arbitrary DNA fragments that map proximal to the AN2 and WT loci.

Partial deletion of chromosome 11p in breast cancer correlates with size of primary tumour and oestrogen receptor level

In a study of DNAs from 100 breast cancer patients and 100 controls, there were no differences in the frequencies of common or rare alleles at the Harvey ras (c-Ha-ras) locus on chromosome 11. However, one Ha-ras allele was deleted from the tumour DNA in 14 of 65 informative patients. Loss of a Ha-ras allele correlates with paucity of oestrogen receptor protein and with increased tumour size at presentation, but is not associated with microscopic evidence of lymph node invasion. The findings on Ha-ras and other informative loci are consistent with the possibility that a tumour suppressor gene involved in the early stages of breast cancer is located on the short arm of chromosome 11.

Molecular nature of genetic changes resulting in loss of heterozygosity of chromosome 11 in Wilms' tumours

In this paper we describe the analysis of genetic changes in chromosome 11 in Wilms' tumours. Using a range of probes for regions 11p15, 11p13 and 11q we have screened DNA from 14 Wilms' tumours together with control DNA obtained from the patients' lymphocytes and their parents. We have been able to demonstrate loss of heterozygosity in 5 of the 14 different Wilms' tumours. In three of these five tumours, loss of heterozygosity did not involve markers for 11p13, 11p15.4 or the proximal region of 11p15.5, but only some markers assigned to the most distal part of 11p15.5. In two of these tumours we could demonstrate unequal mitotic recombination in 11p with breakpoints in the hypervariable regions 5' of the insulin gene and/or 3' of the HRASI proto-oncogene. In one tumour, from a Beckwith-Wiedemann patient, all markers for the region 11q13-pter became hemizygous; the region 11q13-qter remained heterozygous. These results demonstrate that loss of heterozygosity in Wilms' tumours may not necessarily involve the proposed Wilms' tumours locus at 11p13 but may be limited to 11p15.5. This suggests that not only the 11p13 region, but also the 11p15.5 region is involved in Wilms' tumour development. The possible role of both regions in the development of Wilms' tumour is discussed.

Construction of a genetic map of human chromosome 17 by use of chromosome-mediated gene transfer

We used somatic-cell hybrids, containing as their only human genetic contribution part or all of chromosome 17, as donors for chromosome-mediated gene transfer. A total of 54 independent transfectant clones were isolated and analyzed by use of probes or isoenzymes for greater than 20 loci located on chromosome 17. By combining the data from this chromosome-mediated gene transfer transfectant panel, conventional somatic-cell hybrids containing well-defined breaks on chromosome 17, and in situ hybridization, we propose the following order for these loci: pter-(TP53-RNP2-D17S1)-(MYH2-MYH1)-D17Z 1-CRYB1-(ERBA1-GCSF-NGL)-acute promyelocytic leukemia breakpoint-RNU2-HOX2-(NGFR-COLIAI-MPO)-GAA-UM PH-GHC-TK1-GALK-qter. Using chromosome-mediated gene transfer, we have also regionally localized the random probes D17S6 to D17S19 on chromosome 17.

Two anonymous DNA segments distinguish the Wilms' tumor and aniridia loci

The association of Wilms' tumor with aniridia (the WAGR complex) in children with 11p13 chromosomal abnormalities has been established, but the paucity of molecular probes in 11p13 has hampered identification of the responsible genes. Two new anonymous DNA segments have been identified that map to the WAGR region of 11p13. Both DNA probes identify a cytologically undetectable deletion associated with a balanced chromosome translocation inherited by a patient with familial aniridia, but not Wilms' tumor. The same two DNA segments are also included in the distal p13-p14.1 deletion of another patient, who has aniridia, Wilms' tumor, and hypogonadism, but they are not included in the p12-p13 deletion of a third patient, who does not have aniridia but has had a Wilms' tumor. The discovery of this aniridia deletion and these two DNA segments that physically separate the Wilms' tumor and aniridia loci should facilitate identification of the genes in the WAGR locus, beginning with the aniridia gene.

Recessive mechanisms of malignancy

It is increasingly recognised that recessive mutations play an important role in the pathogenesis of many forms of malignancy. Some of the affected loci may prove to be recessively-activated proto-oncogenes, but others are now known to be tumorigenic solely by virtue of their loss or inactivation and therefore form a distinct and novel family of tumour genes. Preliminary evidence suggests that such genes are likely to be functionally heterogeneous and to encode molecules involved in the inhibition of cellular proliferation and/or the induction of differentiation. Their further study is likely to illuminate fundamental mechanisms of normal cellular growth and differentiation as well as having important implications for the pathogenesis and management of cancer.

Hitch-hiking from HRAS1 to the WAGR locus with CMGT markers

The clinical association of Wilms' tumour with aniridia, genitourinary abnormalities and mental retardation (WAGR syndrome) is characterised cytogenetically by variable length, constitutional deletion of the short arm of chromosome 11, which always includes at least part of band 11p13. HRAS1-selected chromosome mediated gene transfer (CMGT) generated a transformant, E65-6, in which the only human genes retained map either to band 11p13 or, with HRAS1, in the region 11p15.4-pter. Human recombinants isolated from E65-6 were mapped to a panel of five WAGR deletion hybrids and two clinically related translocations. We show that E65-6 is enriched congruent to 400-fold for 11p15.4-pter markers and congruent to 200-fold for 11p13 markers. 'Hitch-hiking' from HRAS1 with CMGT markers has allowed us to define seven discrete intervals which subtend band 11p13. Both associated translocations co-locate within the smallest region of overlap for the WAGR locus, which has been redefined by identifying a new interval closer than FSHB.

Human cytochrome P-450 PB-1: a multigene family involved in mephenytoin and steroid oxidations that maps to chromosome 10

The cytochrome P-450 monooxygenase system possesses catalytic activity toward many exogenous compounds (e.g., drugs, insecticides, and polycyclic aromatic hydrocarbons) and endogenous compounds (e.g., steroids, fatty acids, and prostaglandins). Multiple forms of cytochrome P-450 with different substrate specificities have been isolated. In the present paper we report the isolation and sequence of a cDNA clone for the human hepatic cytochrome P-450 responsible for mephenytoin (an anticonvulsant) oxidation. The mephenytoin cytochrome P-450 is analogous to the rat cytochrome P-450 form termed PB-1 (family P450C2C). We also report that human PB-1 is encoded by one of a small family of related genes all of which map to human chromosome 10q24.1-10q24.3. The endogenous role of this enzyme appears to be in steroid oxidations. This cytochrome P-450 family does not correspond to any of the hepatic cytochrome P-450 gene families previously mapped in humans.

Analysis of WAGR deletions and related translocations with gene-specific DNA probes, using FACS-selected cell hybrids

We used the fluorescence-activated cell sorter (FACS) to select a series of somatic cell hybrids with deleted or translocated chromosome 11 segregated from its normal homolog. Analysis of these cell hybrids with gene-specific probes and for cell-surface marker expression has allowed us to order the markers and define a smallest region of overlap (SRO) for deletions associated with the WAGR (Wilms' tumor, aniridia, genitourinary abnormalities, and mental retardation) region of chromosome 11. Two translocation breakpoints in 11p13 (one associated with familial aniridia and one with a sporadic case of congenital renal dysfunction resulting from urethral and ureteral atresia) map within this SRO.

Molecular genetic approaches to the analysis of human ophthalmic disease

In this review of the recent literature, the contribution that the new techniques of molecular genetics has made in the analysis and diagnosis of human ophthalmic conditions is presented and discussed. Among the disorders reviewed are X-linked retinitis pigmentosa, Norrie's disease, gyrate atrophy and retinoblastoma, and there are also sections on crystallins and visual pigments.