c-Ha-ras1 is not deleted in aniridia-Wilms' tumour association.

Non-random tumour-specific chromosomal abnormalities have been observed in cells of many different human tumours. In Wilms' tumour (WT) and retinoblastoma, a chromosomal deletion occurs germinally or somatically and has been considered an important step in tumour development. One class of potential cellular transforming genes comprises the cellular homologues of the transforming genes of highly oncogenic retroviruses. A remarkable concordance between the chromosomal location of human cellular oncogenes and the breakpoints involved in acquired chromosomal translocations is becoming apparent in various cancers: the oncogenes c-mos, c-myc and c-abl are located at the breakpoints that occur in acute myeloblastic leukaemia, Burkitt's lymphoma and chronic myelocytic leukaemia respectively. Thus when the oncogene c-Ha-ras1 was localized to the short arm of human chromosome 11 (refs 6-8; region 11p11 leads to p15 and not 11p13 as stated in ref. 5), it was proposed as a possible aetiological agent in the aniridia-WT association (AWTA) that results from a deletion of 11p13 (although a transforming gene recently isolated from a WT cell line (G401) was shown not to be homologous to either c-Ha-ras or c-Ki-ras9). We have now looked for deletion or rearrangement of c-Ha-ras1 in the DNA from four subjects with del(11p13)-associated predisposition to Wilms' tumour, aniridia, genitourinary abnormalities and mental retardation. We report here that in no case is c-Ha-ras1 deleted, and we have further refined its location to 11p15.1 leads to 11p15.5. On the basis of enzyme studies and direct gene dosage determination for c-Ha-ras1 and beta-globin in neoplastic and non-neoplastic tissues from one patient, we conclude that deletion of the normal counterpart of 11p cannot account for the development of the tumour.

Catalase determination in various etiologic forms of Wilms' tumor and gonadoblastoma.

We have previously mapped the gene coding for catalase to 11p13 by gene dosage analysis. Deletion of this chromosomal region causes aniridia, mental retardation, and predisposition to Wilms' tumor (WT). In the present study, 22 patients with various etiologic forms of WT and/or aniridia were investigated. The catalase (CAT) level and karyotype were examined in order to determine the linkage and the gene ordering on chromosome number 11 of the different loci involved. The CAT concentration was normal in the 19 cases without detectable chromosomal abnormalities.

Retinoblastoma, deletion 13q14, and esterase D: application of gene dosage effect to prenatal diagnosis.

Esterase D (ESD) gene dosage studies were performed on amniotic cells from a fetus at risk for del 13q14. The mother was a balanced carrier of an insertion in chromosome #20: 46,XXins(20;13)(p12;q1307q14.3). She had already given birth to a monosomic child with retinoblastoma (Rb) and to a phenotypically normal child trisomic for the same 13q14 segment. Both sibs displayed the expected proportionate gene dosage effects for ESD. A 153% value of ESD activity was found in the amniotic cells indicating unambiguously that the fetus was not monosomic for segment 13q14 and therefore not at increased risk for Rb. The mother delivered a phenotypically normal child who was confirmed to be trisomic for segment 13q14 by cytogenetic analysis and by gene dosage studies for ESD in cord blood cells and in lymphoblastoid cells.

Assignment of phosphoglycerate mutase (PGAMA) to human chromosome 10. Regional mapping of GOT1 and PGAMA to subbands 10q26.1 (or q25.3).

Human phosphoglycerate mutase (PGAM, EC 2.7.5.3) is under the control of two structural loci that code for subunits A and B. By means of gene-dosage studies, Bücher et al. (1980) have assigned the loci for GOT1 and PGAMA to chromosome 19 of Mus musculus. Because of the known homologies between human and murine chromosomes, gene dosage studies were carried out in erythrocytes from one patient trisomic for the entire band 10q26 and from another patient monosomic for 10q26.2 and q26.3. Results were compatible with the assignment of PGAMA and GOT1 to 10q26.1 (or 10q25.3).

[Ring chromosome 10: 46,XX,r(10)(p15q26)]. / Chromosome 10 en anneau: 46,XX,r(10)(p15q26).

A teenage girl with growth and mental retardation, urinary tract and eye abnormalities was found to have an r(10)(p15q26) in blood cells. Quantitative evaluation of seven red cell enzymes including three (HK1, TGOS, PGAMA) known to be on chromosome 10, gave normal values.

Inverted tandem duplication of the short arm of chromosome 8: a non-random de novo structural aberration in man. Localization of the gene for glutathione reductase in subband 8p21.1.

Two patients with an inverted duplication of bands 8p21-p23 are described. The gene for glutathione reductase (GSR; E.C.1.6.4.2) has previously been localized to band 8p21. In one of the patients subband 8p21.1 was included in the duplication; GSR activity in the red blood cells was increased. In the other patient, subband 8p21.1 was not included in the duplication and GSR activity was normal. This allows GSR to be assigned to subband 8p21.1. Including the present 2 patients, at least 13 cases of this abnormality have been published. We have obtained data on at least 8 further cases (unpublished). We conclude that inv dup (8p) is a non-randomly occurring de novo structural aberration in man. The GSR results in our cases prove that breakpoints can be different in different patients. Clinical symptoms and signs include some common features but show marked interpatient variation which should, at least in part, be caused by the differences in break-points. A detailed collaborative study to determine the clinical and epidemiological features of this entity is recommended.

Gene dosage effect for GALT in 9p trisomy and in 9p tetrasomy with an improved technique for GALT determination.

A new born male and a three-year-old female with various dysmorphic features were both found to have to have a supernumerary chromosome. Clinical and cytogenetic findings confirmed the existence of a pure de novo 9p tetrasomy in the first case and a pure de novo 9p trisomy in the second case. Gene dosage effects were demonstrated for galactose-1-phosphate uridyltransferase GALT (EC 2.7.7.12) using an improved method for the assay of this enzyme in red blood cells. These findings are in agreement with previous results on similar cases and therefore confirm the assignment of the locus for GALT to 9p.

Retinoblastoma-del(13q14): report of two patients, one with a trisomic sib due to maternal insertion. Gene-dosage effect for esterase D.

Two cases of del(13)-retinoblastoma are reported. Case 1, a 13-month-old male, was monosomic due to the malsegregation of the maternal ins(20;13)(p12;q1307q14.3). The patients's sister was trisomic for 13q1307q14.3 with no evident phenotypic effect. Case 2 was a 20-month-old female with a denovo del(13)(q1303q14.3). In both instances esterase D activity showed a remarkable gene-dosage effect in monosomy, disomy, and trisomy, thus confirming the assignment of the gene locus to 13q14, and more precisely to the proximal half of this band. In all instances, the ESTD phenotypes were 1-1. It is suggested that esterase D activity should become an important diagnostic criteria for the various etiological forms of retinoblastoma.