Computer-assisted analysis of chromosomal abnormalities: detection of a deletion in aniridia-Wilms' tumor syndrome

Chromosomal Abnormalities and Glaucoma: A Case of Congenital Glaucoma with Trisomy 8q22-Qter/ Monosomy 9p23-Pter

PURPOSE

To present a case of congenital glaucoma with an unbalanced translocation trisomy 8q22-qter/monosomy 9p23-pter, resulting in trisomy of the GLC1D locus. To perform a literature review of chromosomal abnormalities associated with glaucoma.

METHOD

A case report of a family with balanced translocation without glaucoma and unbalanced translocation with congenital glaucoma. PubMed and OMIM databases were searched for reports of chromosomal abnormalities and glaucoma.

RESULTS

Other case reports of congenital glaucoma with chromosomal abnormalities in this region were identified. A review of cytogenetics in southeastern Australia found nine cases involving the loss of 9p23 and 10 cases involving mosaicism for trisomy 8, but none had congenital glaucoma. A review of the literature identified reports of glaucoma and chromosomal abnormalities in regions with glaucoma loci mapped by conventional linkage analysis. These include the loci GLC1B, GLC1C, GLC1D, GLC1F, GPDS1, and RIEG2.

CONCLUSION

The study of patients with glaucoma and chromosomal abnormalities may help to identify new glaucoma genes. Ophthalmologists can assist with this by requesting cytogenetic studies on congenital and developmental glaucoma cases and interacting with ophthalmic genetics researchers.

[Congenital glaucoma and trabeculodysgenesis. Clinical and genetic aspects]

Congenital glaucoma is generally related to an iridocorneal angle malformation, with an obstacle to aqueous humor outflow. This spectrum of diseases can involve the angle, the iris and the cornea. The diagnosis relies on characteristic signs and is confirmed by an examination under general anaesthesia and paraclinical examinations (especially echography). An early diagnosis is essential for beginning surgical treatment. Several filtering surgery techniques with equivalent intraocular pressure results are available, but visual function must be protected in all cases. In many cases, genetic counseling relies on a careful clinical analysis and sometimes on a molecular analysis. A number of ocular and/or general abnormalities can be accompanied by glaucoma in infants and children. They must be screened in case of associated signs, but the existence of these abnormalities leads to suspicion of associated glaucoma.

Syndrome-related chromosome-specific radiation-induced break points of various inherited human metabolic disorders

The frequency, distribution pattern and localisation of gamma radiation-induced break points on the chromosomes of patients with various inherited metabolic disorders were studied to detect: (i) whether the break point distribution following irradiation is random and proportional to the length or the DNA content of the chromosome, or non-proportionally distributed on their length and at times clustering to form hot spots on certain region of the chromosomes; and (ii) to find whether there exists a syndrome-related chromosome-specific pattern of radiation-induced break points. Lymphocyte cultures from patients of haemophilia, ichthyosis, Duchenne muscular dystrophy, retinitis pigmentosa and alpha-thalassemia, whose defective gene loci were located by DNA probe method, were subjected to 3Gy of gamma radiation at G(0). The chromosomal break point analysis was carried out on all the 23 types of chromosomes (excluding Y chromosome) using G banding and FISH painting. The exact location of the break points on G-banded chromosomes was identified using a semi-automated microscope densitometer system (Leitz MPV2). In normal individuals in all the chromosomes except the chromosome 1, a random distribution of break points proportional to their length based on their DNA content was observed. However, in all the syndromes studied a mixture of hypersensitive chromosomes with a non-random distribution pattern of chromosomal break points invariably clustering to form hot spots, and chromosomes with random distribution of break points proportional to their length were observed. The hypersensitive chromosomes and their hot spots were syndrome-specific.

Hereditary cancer: two hits revisited

According to a "two-hit" model, dominantly inherited predisposition to cancer entails a germline mutation, while tumorigenesis requires a second, somatic, mutation. Non-hereditary cancer of the same type requires the same two hits, but both are somatic. The original tumor used in this model, retinoblastoma, involves mutation or loss of both are somatic. The original tumor used in this model, retinoblastoma, involves mutation or loss of both copies of the RB1 tumor-suppressor gene in both hereditary and non-hereditary forms. In fact, most dominantly inherited cancers show this relationship. New dominantly inherited cancers show this relationship. New questions have arisen, however. When a tumor-suppressor gene is ubiquitously expressed, why is there any specificity of tumor predilection? In some instances, it is clear that two hits produce only a benign precursor lesion and that other genetic events are necessary. As the number of necessary events increase, the impact of the germline mutation diminishes. The number of events is least for embryonal tumors, and relatively small for certain sarcomas. Stem-cell proliferation evidently plays a key role early in carcinogenesis. In some tissues it is physiological, as in embryonic development and in certain tissues in adolescence. In adult renewal tissues, the sites of the common carcinomas, mutation may be necessary to impair the control of switching between renewal and replicative cell divisions; the APC gene may be the target of such a mutation.

Introduction to the genetics of primary renal tumors in children

Wilms tumor can be explained only partially by the "two hit" model that was originally developed for retinoblastoma. Heterogeneity of two kinds operates. The first is that four other primary tumors are regularly observed in children, and the second is that Wilms tumor itself appears to represent more than one genetic entity. All five of these primary renal tumors arise from primary or secondary mesenchyme, renal blastema, or renal epithelium. Mesoblastic nephroma, and possibly clear cell sarcoma, may have some genetic affinity with Wilms tumor, but rhabdoid tumor of the kidney and renal carcinoma do not. At least three different genes seem to be important in the origin of Wilms tumor. One, WT1, whose mutations may be associated with aniridia, may follow the "two hit" model in that there are cases in which both copies of the gene are defective or lost, as expected for a tumor suppressor gene. A second gene, which is associated with Beckwith-Wiedemann Syndrome (BWS) and which has not been cloned, appears to be imprinted in females, and may have an oncogene function. It is evidently activated by gain of a paternal allele or by loss of the inactive, but possibly trans-sensing, maternal allele. Activation of the insulin-like growth factor II gene may be a final common pathway for mutation in both WT1 and BWS. A third gene is unlinked to either of the other two, but its location and function are unknown. It shares with WT1 specificity for Wilms tumor, which is not true of the BWS gene.

Two cases of cri-du-chat syndrome with mild phenotypic effect but with different size of 5p deletion

The clinical and cytogenetic findings of two cases of cri-du-chat syndrome are described. Both cases were females with only slight growth delay, moderate mental disability and minimal phenotypic effects. The mild phenotype was difficult to correlate with the karyotype, which on GTG and RBG banding showed that each had a regular de novo 5p deletion. The deletion in Case 1 was terminal - 46,XX,del(5) (pter----p15.2:) and in Case 2 it was interstitial - 46,XX,del(5) (pter----p15.2::p13.3----qter). The deletion in Case 2 was considerably larger than in Case 1.

The N-myc proto-oncogene and IGF-II growth factor mRNAs are expressed by distinct cells in human fetal kidney and brain

We studied the expression of the N-myc proto-oncogene and the insulin-like growth factor-II (IGF-II) gene in human fetuses of 16-19 gestational wk. Both genes have specific roles in the growth and differentiation of embryonic tissues, such as the kidney and neural tissue. Since continued expression of N-myc and IGF-II mRNAs is also a characteristic feature of Wilms' tumor, a childhood neoplasm of probable fetal kidney origin, we were particularly interested in the possibility that their expression might be linked or coordinately regulated in the developing kidney. Expression of N-myc mRNA was observed in the brain and in the kidney by Northern hybridization analysis. In in situ hybridization of the kidney, N-myc autoradiographic grains were primarily located over epithelially differentiating mesenchyme while most of the mesenchymal stromal cells showed only a background signal with the N-myc probe. N-myc mRNA was detectable throughout the developing brain with a slight accentuation in the intermediate zone cells in between the subependymal and cortical layers. Thus, even postmitotic neuroepithelial cells of the fetal cerebrum expressed N-myc mRNA. In Northern hybridization, IGF-II mRNA signal was abundant in the kidney but much weaker, though definite, in the brain. The regional distribution of IGF-II mRNA in the kidney was largely complementary to that of N-myc. IGF-II autoradiographic grains were located predominantly over the stromal and blastemal cells with a relative lack of hybridization over the epithelial structures. In the brain, IGF-II mRNA was about two- to threefold more abundant in the subependymal and intermediate layers than in the cortical plate and ependymal zone, respectively. The fetal expression patterns of the N-myc and IGF-II mRNAs are reflected by the types of tumors known to express the corresponding genes during postnatal life such as Wilms' tumor. However, the apparent coexpression of the IGF-II and N-myc genes in immature kidneys occurs largely in distinct cell types.

Oncogenes and tumor suppressor genes

The artificial selection of the directly acting or acute RNA tumor viruses for high transforming ability has led to the isolation of defective retroviral genomes that have picked up, by accidental recombination, some of the important genes that influence, trigger or regulate cell division. These genes belong to at least four functionally different groups. Each of them can contribute to tumor development and/or progression after activation by structural or regulatory changes. Growth factor genes may act as oncogenes following constitutive activation in a cell that normally responds to, but does not produce, the corresponding growth factor (the autocrine model, exemplified by sis). Growth factor receptors may be fixed in a state of continuous, faulty signalling by the truncation of their external, ligand binding portion (examples: erb-B, fms). Genes coding for proteins involved in signal transduction may be activated by point mutations in certain, important domains (example: the ras-family). DNA binding proteins, presumably involved in DNA replication may drive cell division after constitutive activation by retroviral insertion, chromosomal translocation or gene amplification (example: the myc-family).

The approaching era of the tumor suppressor genes

Genes that can inhibit the expression of the tumorigenic phenotype have been detected by the fusion of normal and malignant cells, the phenotypic reversion of in vitro transformants, the induction of terminal differentiation of malignant cell lineages, the loss of "recessive cancer genes," the discovery of regulatory sequences in the immediate vicinity of certain oncogenes, and the inhibition of tumor growth by normal cell products. Such tumor suppressor genes will probably turn out to be as, if not more, diversified as the oncogenes. Consideration of both kinds of genes may reveal common or interrelated functional properties.

Recurrent deletions of chromosomes 11q and 3p in anal canal carcinoma

A cytogenetic study of 8 cases of anal canal cancer, including 1 cloacogenic and 7 squamous-cell carcinomas, was performed. All tumors exhibited chromosomal abnormalities. A rearrangement involving the long arm of chromosome 11 was seen in all instances, and, with the exception of the i (11q) found in one tumor, all the observed rearrangements resulted in a deletion of the distal segment. Rearrangements of chromosome 3, detected in 6 tumors, led to a deletion of the short arm in 5 cases. The association of these 2 deletions may characterize the anal canal carcinoma, the smallest common deleted segments being distal to 11q22 or q23 and 3p22.

The molecular genetics of retinoblastoma and Wilms' tumor

Retinoblastoma and Wilms' tumor in children are sometimes associated with small constitutional chromosome deletions on chromosomes 13 and 11, respectively. This finding has highlighted regions of the human genome which are potentially important in the predisposition to the development of cancer. By using techniques in molecular biology, it is possible to isolate DNA sequences from specific chromosomes. Then, by using either a panel of somatic cell hybrids containing different overlapping deletions or in situ hybridization, it is possible to assign these DNA sequences to regions of particular chromosomes. DNA sequences isolated from within the frequently deleted regions will prove useful not only to improve understanding of the basic mechanism underlying cancer predisposition, but also to possibly allow prenatal diagnosis for those at risk.

Cytogenetics of small cell carcinoma of the lung

Nineteen cell lines derived from various malignant tissues of 15 patients with small cell carcinoma of the lung (SCCL) have been studied. The results showed heterogeneity in all cell lines, with no one consistent abnormality among them. Cell lines from 11 of the patients had minute and double minute chromosomes, and cell lines from 2 patients had abnormally banding regions, designated as ABRs, as distinguished from homogeneously staining regions (HSRs). The latter 2 and several of the former cell lines were derived from specimens taken before the patients were placed on therapy. All but 2 of the cell lines had a constant marker load, consisting of 24%-35% of the complement. Some markers remained stable through months and years of culture life, while other markers came and went. Chromosomes #1, #6 and #11 were most frequently involved in marker formation in the cell lines, and these were compared to similar markers in direct bone marrow preparations. Chromosome #1 markers were of variable structure, whereas #6 and #11 most often took the form of 6q- and 11p+ markers, with breakpoints most frequently at 6q23-25 and 11p11-12. A 3p- marker was found in a minority of cell lines. All of these markers were also found in direct marrow preparations from some patients with SCCL. Nonmonoclonal tumors arose from inoculation of bimodal cell lines into nude mice, but population selection by undetermined mechanism was evident. Cytogenetic parameters showed no positive correlation with hormone production by these cell lines.

Aniridia. A review

Aniridia occurs as a phenotypically heterogeneous condition which may be inherited as an autosomal dominant disorder or as part of several systemic syndromes. It has been linked with the loci of chromosomes 1 and 2 and associated with the deletion of the p-13 band of chromosome 11. Aniridia may occur in a highly penetrant form in association with other ocular abnormalities with poor vision or in a more variable form with good vision. The recognition of a child with sporadic aniridia should alert physicians to the increased risk of development of Wilms' tumor.

Regional mapping of catalase and Wilms tumor--aniridia, genitourinary abnormalities, and mental retardation triad loci to the chromosome segment 11p1305----p1306

Gene dosage effects for catalase (CAT) were studied in two unrelated patients with an interstitial deletion involving 11p13 to determine precisely the sites of the genes for CAT and the Wilms tumor--aniridia, genitourinary abnormalities, and mental retardation triad (WAGR) in the 11p13 band. Case 1 had the aniridia-Wilms tumor association, and case 2 showed the AGR triad. The karyotypes identified by high resolution banding techniques were 46,XY,del(11)(pter----p13::p11.11----qter) for case 1 and 46,XY,t(2;17)(q23;q25),del(11)(pter----p13::p11.2----qter) for case 2. In both cases, the distal breakpoints of the deleted chromosomes 11 appeared to have occurred on the middle portion of 11p13 (11p1305----p1306). The level of erythrocyte CAT activities in case 1 was reduced (47% of normal), while that in case 2 was normal. The results suggested not only that both the CAT and WAGR should be mapped to chromosome region 11p1305----p1306, but also that in this region the CAT locus is more distally placed than the WAGR locus. Because of the proximity of the two gene loci, assays of erythrocyte CAT may be useful to identify a submicroscopic deletion in some patients with sporadic aniridia and to predict a risk of developing Wilms tumor.

Association of del(11)(p15.1p12), aniridia, catalase deficiency, and cardiomyopathy

We report another patient with del(11p) and aniridia, catalase deficiency, and cardiomyopathy. This association is confirmed from a review of previously reported cases. Since other dysplasias are known in this syndrome, the hypertrophic cardiomyopathy in del(11p) children may also represent an abnormality of tissue development.

Computer-aided analysis of chromosomal aberrations occurring in an abnormal human karyotype

A semi-automatic method for recognition of chromosomal changes is presented: from a coded description of an abnormal chromosome (formulated with the aid of an R-banding technique), a computer program makes simulations to reconstitute this chromosomal image from a group of normal chromosomes. Nine types of aberrations (see text) can thus be recognized and the aggregate structure of a group of abnormal chromosomes occurring in a human karyotype can also be rediscovered.

Aniridia caused by a heritable chromosome 11 deletion

A child with aniridia, multiple anomalies, severe failure to thrive, and severe psychomotor retardation is shown to have a syndrome similar to, though more severe than, other patients with overlapping deletions of the short arm of chromosome 11 (Pediatrics 64:604, 1978). Her deletion (46,XX,del [11p] [pter yields p14::p11.3 yields qter]) was derived from her mother, who has a chromosome 11 shift (46,XX,der [11] [pter yields p14::p11.3 yields q22::p14 yields p11.3::q22 yields qter]). The significance of del (11p) in the aniridia-Wilms' tumor association is discussed, and the del (11p) basis for aniridia is compared with other genetic bases for aniridia.

Chromosome 8 abnormalities as components of neoplastic and hematologic disorders

Publications involving patients with any abnormality of chromosome 8 have been reviewed in detail. For the time period involved, a total of 277 cases were found, including 74 instances of congenital aneuploidy, 130 instances of acquired aneuploidy, 38 instances of congenital rearrangements, and 35 instances of acquired rearrangements. A total of 170 cases of neoplastic and hematologic disorders were included; three were associated with congenital aneuploidy, two with congenital rearrangements, and the remaining 165 with acquired aberrations. The specific disorders ranged from sideroblastic anemia through chronic and acute leukemia to solid tumors. There appears to be a definite, though non-specific correlation between congenital or acquired chromosome 8 abnormalities and the development of certain types of neoplastic growth.

The role of genetic factors in the etiology of Wilms' tumor: two pairs of monozygous twins with congenital abnormalities (aniridia; hemihypertrophy) and discordance for Wilms' tumor

Wilms' tumor was diagnosed in two children each of whom has an identical twin. In one of the pairs of twins the aniridia syndrome with psychomotor retardation was present in both children, but Wilms' tumor was found in only one. In the other twins hemihypertrophy as well as Wilms' tumor were identified in one child, whereas neither of these abnormalities was present in her twin sister. These findings lend support to a hypothesis that the development of Wilms' tumor requires the occurrence of two successive mutational events, one of which may be a germinal mutation. The presence of aniridia, hemihypertrophy, or other associated congenital abnormalities may aid in distinguishing between hereditary and sporadic forms of Wilms' tumor.

Wilms' tumor--model of a curable pediatric malignant solid tumor

Wilms' tumor is the model of the treatment of a pediatric solid tumor. Initially it appeared that multi-modality therapy, consisting of transabodominal nephrectomy, post-operative radiation therapy to the tumor bed and adjuvant, single agent chemotherapy provided the highest likelihood of disease-free survival. The identification of important prognostic factors, such as histology, tumor weight, lymph node involvement and age at diagnosis has led to a re-examination of the treatment of Wilms' tumor. Future therapeutic developments will include the administration of less therapy to some well defined groups of patients, and the exploration of new programs for patients who have been demonstrated to have a poor prognosis using currently accepted treatment techniques.

Partial deletion of long arm of chromosome 11: del (11) (q23)

The cytogenetic analysis of an infant with multiple congenital anomalies revealed a small deletion of the long arm of one No. 11 chromosome: 46,XX,del(11)(q23). The main clinical manifestations included: ocular colobomata, absent philtrum, severe congenital heart disease, contractures of the large joints and skin pigmentation. Both parents showed a normal chromosome constitution. In comparison to the previously reported cases of 11q-, the patient presented here had more severe congenital anomalies. The correlation of the size of the deletion, and the location of the break, with the physical findings is discussed.

Small structural changes of chromosome 8. Two cases with evidence for deletion

Two patients are described whose clinical features are interpreted as resulting from simple deletion of, respectively, bands p12 and q242 of chromosome 8.

Genetic aspects of childhood tumours

Present concepts on the etiology of childhood tumours are reviewed. The difference in clinical manifestations of the hereditary and nonhereditary types are illustrated with data on retinoblastoma and on nephroblastoma. Notwithstanding these differences it is most likely that the fundamental etiologic process is the same in both and that it consists in successive mutational events. The possible consequences of the association of retinoblastoma with a deletion of chromosome 13 in some cases are discussed. Several explanations for the association of Wilms' tumour and aniridia are also discussed.