[Comprehensive analysis of changes in critical chromosomal regions and the development of DNA-diagnosis protocols]. / Kompleksnyi analiz izmenenii kriticheskikh raionov khromosom i razrabotka protokolov DNK-diagnostiki.

A number of genetic syndromes and cancer are caused by chromosomal microstructural rearrangements. It is sometimes impossible to detect this pathology microscopically. A complex of molecular methods makes it possible to detect subchromosomal deletions, point mutations, and functional anomalies on the respective genes, which cause a disease. Achievements of comprehensive analysis have been demonstrated in cases of some well-known diseases, the Prader-Willi syndrome, Engelmann's syndrome, the Martin-Bell syndrome, hereditary multiple exostotic chondrodysplasia, and retinoblastoma. DNA-diagnosis protocols are the result of this study.

Heterochromatiun C sizes distribution of chromosomes 1, 9, 16 and y in a sample of the Mexican population: comparison of two quantitative methods of measurement

En 147 mexicanos del sexo masculino, se investigó la distribución de los tamaños de los bloques de heterocromatina C de los cromosomas 1, 9, 16 e Y. Los tamaños fueron establecidos por dos métodos cuantitativos: longitud y área. Las curvas de distribución fueron muy cercanas a la normal con un leve sesgo positivo, sugiriendo que el tamaño de los segmentos C es un rasgo multifactorial continuo. Las comparaciones de nuestros resultados del largo mostraron ser muy similares con aquellos de otros grupos étnios, sugiriendo que esta característica presenta poca variabilidad racial. Utilizándose como criterio a la media y los intervalos de confianza de la varianza los tamaños de los segmentos C se clasificaron en 5 categorías: muy pequeños, pequeños, intermedios, grandes y muy grandes, encontrándose en todas las mediciones que la frecuencia de las variantes muy grandes fue mayor que las de tamaño muy pequeño. Los coeficientes de variación (CV) de ambos métodos fue aproximadamente del 5%, sin embargo del CV intercelular del área fue la mitad que el del largo. El CV de la muestra fue mayor para el área que para el largo, sugiriendo estos datos, que la medición de la primera, discrimina mejor variaciones de menor tamaño. En conclusión, consideramos que aunque el método de medir el área es más complicado y requiere de mayor tiempo que la cuantificación del largo, el primero determina mejor el tamaño de los segmentos de heterochromatina C

Male pseudohermaphroditism, partial androgen receptors defect, 11p13 deletion: indication of gene localization.

A partial androgen receptor defect was found in a boy with male pseudohermaphroditism and an 11p13 deletion. We hypothesize that a gene responsible for the function or structure of androgen receptors might be localized in the 11p13 band or in close proximity to it.

Chromosomal mosaicism in the Killian/Teschler-Nicola syndrome.

We report a patient with the Killian/Teschler-Nicola/Pallister mosaic syndrome in association with a cytogenetic abnormality. This patient is the first reported to have lymphocyte mosaicism for an isochromosome of 12p. All other patients with the Killian syndrome have had normal lymphocyte karyotypes, although mosaicism for a similar isochromosome of 12p has been reported in the fibroblasts of most patients with the Killian syndrome.

Duplication (12q) syndrome in female cousins, resulting from maternal (11;12) (p15.5;q24.2) translocations.

We have studied female cousins with partial duplication of 12q. The cousins' mothers (who are sisters) and the maternal grandmother and great grandmother carried a balanced translocation between chromosomes 11 and 12. We have compared our patients with eight other reported cases of partial duplication of the same chromosome segment (12q24----12qter). Placement of the extra material seems to have little effect on the anomalies present; (only two other cases involved chromosome 11). We propose that our patients provide further evidence that duplication of 12q leads to a clinically identifiable syndrome.

Enhanced expression of epidermal growth factor receptor correlates with alterations of chromosome 7 in human pancreatic cancer.

Recently, the gene for the epidermal growth factor (EGF) receptor has been mapped to chromosome 7p, the short arm of chromosome 7 [Shimizu, N., Kondo, I., Gamou, M. A., Behzadian, A. & Shimizu, Y. (1984) Somatic Cell Mol. Genet. 10, 45-53]. Utilizing EGF binding in saturation studies, karyology, and cDNA hybridization experiments, we have sought to determine whether there is a correlation between dosage or alteration of chromosome 7 and enhanced expression of EGF receptor in cultured human pancreatic carcinoma cells. Saturation binding studies with 125I-labeled EGF were performed at 4 degrees C with four established human pancreatic cancer cell lines: T3M4, PANC-1, COLO 357, and UACC-462. Analysis of binding data revealed enhanced numbers of EGF receptors in all four cell lines. Chromosome banding analysis revealed clonal structural alterations of chromosome 7p in the cell lines T3M4, PANC-1, and COLO 357, whereas UACC-462 displayed multiple copies of chromosome 7. Hybridization studies using a radiolabeled EGF receptor cDNA probe failed to demonstrate DNA sequence amplification in any cell line but confirmed the presence of EGF receptor mRNA in these cells in approximate proportion to EGF receptor number. Our results suggest that enhanced expression of EGF receptor in human pancreatic cancer can be associated with either structural or numerical alterations of chromosome 7.

Amplification and rearrangement of Hu-ets-1 in leukemia and lymphoma with involvement of 11q23.

The Hu-ets-1 oncogene was found to be rearranged and amplified 30-fold in one case of acute myelomonocytic leukemia in which a homogeneously staining region occurred on 11q23; the oncogene was rearranged and amplified approximately tenfold in a case of small lymphocytic cell lymphoma with an inverted insertion that also involved band 11q23. This work suggests that Hu-ets-1 is an unusual oncogene that can help explain the common involvement of chromosome band 11q23 in various subtypes of hematopoietic malignancies.

Heterogeneity of chromosome 22 breakpoint in Philadelphia-positive (Ph+) acute lymphocytic leukemia.

In chronic myelogenous leukemias (CML) with the t(9;22)(q34;q11) chromosome translocation the breakpoints on chromosome 22 occur within a 5.8-kilobase segment of DNA referred to as "breakpoint cluster region" (bcr). The same cytogenetically indistinguishable translocation occurs in approximately 10% of patients with acute lymphocytic leukemias (ALL). In this study we have investigated the chromosome breakpoints in several cases of ALL carrying the t(9;22) translocation. In three of five cases of ALL we found that the bcr region was not involved in the chromosome rearrangement and that the 22q11 chromosome breakpoints were proximal (5') to the bcr region at band 22q11. In addition, we observed normal size bcr and c-abl transcripts in an ALL cell line carrying the t(9;22) translocation. We conclude, therefore, that if c-abl is inappropriately expressed in ALL cells without bcr rearrangements, the genetic mechanism of activation must be different from that reported for CML.

Localization of the human NCAM gene to band q23 of chromosome 11: the third gene coding for a cell interaction molecule mapped to the distal portion of the long arm of chromosome 11.

cDNA clones containing sequences coding for the murine neural cell adhesion molecule (N-CAM) were used in Southern hybridizations on human genomic DNA and demonstrated approximately 90% homology between human and murine NCAM genes. In situ hybridization with one of these clones was performed on human metaphase chromosomes and allowed the localization of the human NCAM gene to band q23 of chromosome 11. The genes for two other cell surface molecules believed to be involved in cell-cell interactions, Thy-1 and the delta chain of the T3-T cell receptor complex, have recently been localized to the same region of chromosome 11 in man. Moreover, this region of the human chromosome 11 appears to be syntenic to a region of murine chromosome 9 that also contains the staggerer locus: staggerer mice show abnormal neurological features which may be related to abnormalities in the conversion of the embryonic to the adult forms of the N-CAM molecule.

[C-polymorphism of chromosomes 1, 9, 16 and Y in newborn infants of various gestational ages]. / C-polimorfizm khromosom 1, 9, 16 i Y u novorozhdennykh detei razlichnogo gestatsionnogo vozrasta.

Comparative evaluation of absolute C-segment lengths of chromosomes 1, 9, 16 and Y in new-born children of different gestational age has revealed no significant differences in their value between individuals with unfinished intrauterine development and those born in time.

Configuration and expression of the T cell receptor beta chain gene in human T-lymphotrophic virus I-infected cells.

We studied the configuration and expression of the gene encoding the beta chain of the T cell receptor (TCR beta) in cell lines and primary tumor cells infected by the human T cell leukemia/lymphoma (lymphotrophic) virus type I (HTLV-I). Most of the cell lines and all the primary tumor cells showed rearrangement of the TCR beta gene, and in each case the rearrangement was distinct. The majority of cases examined were clonal with respect to a particular TCR beta gene rearrangement. Primary tumor cells from one case (SD) were found to have a tandem duplication of a portion of chromosome 7; this appears to have resulted in the presence of three alleles of the TCR beta gene, each of which is arranged differently. This suggests that the chromosomal abnormality, and possibly infection by HTLV-I, occurred before TCR beta gene rearrangement. Cell lines infected by HTLV-I express levels of TCR beta mRNA similar to PHA stimulated lymphocytes, suggesting that this gene is not transcriptionally activated as a result of infection by HTLV-I. Cloned T cells of known antigen specificity that are infected by HTLV-I in vitro show impairment of immune function, including loss of antigen-specific responsiveness and the acquisition of alloreactivity. Comparison of the configuration of the TCR beta gene before and after infection revealed no changes detectable by Southern blot analysis. Levels of expression of the TCR beta gene at the mRNA level and surface expression of the T3 complex were also not significantly altered, suggesting that changes in immune function cannot be attributed to quantitative changes in the TCR molecule. The configuration of the TCR beta gene in primary tumor cells infected by HTLV-I was compared with that in the derived cell lines. In all pairs examined, the configuration in the primary tumor cells was different from that in the cell lines, strongly suggesting that the cells that grow in culture are not the original neoplastic cells.

T cell receptor and immunoglobulin gene rearrangements in acute myeloblastic leukemia.

The organization and expression of the beta chain of T cell antigen receptor gene (beta-TCR) and Ig H and L chain genes were analyzed by Southern blot technique in 24 patients with a diagnosis of acute myeloblastic leukemia (AML). Rearrangements of the beta-TCR genes were seen in DNA samples from 3 of the 24 patients. One of these three patients also showed rearrangement of the Ig H chain gene. RNA samples from all three patients expressed a beta-TCR gene transcript on dot blot analysis. However, on Northern blot analysis, one patient expressed an incomplete 1.0 kb transcript and no Ig H chain mRNA, despite a rearranged configuration. The karyotypes of two of these patients showed abnormalities involving chromosome 7. Rearrangements of T cell antigen receptor genes may occur in nonlymphoid malignancy, and is consistent with the concept of lineage infidelity in AML.

Nonrandom chromosomal changes in retinoblastomas.

The analysis of the karyotype in 76 retinoblastomas (24 our cases and 52 described in the literature) has revealed nonrandom changes of Iq, 6p, 13, 16 and the sex chromosomes. Complete or partial trisomy Iq was observed in 44 out of 76 tumours. Tetra-or trisomy 6p was found in 35 and 6 cases respectively. Chromosome 13 monosomy or its long arm deletion was described in 11 tumours. Monosomy 16 and loss of the X or Y--in 18 and 12 cases. The specific feature of retinoblastoma karyotype is presence (along with two normal homologues of the pair 6) of the marker chromosome i (6p). Possible causes of unexpectedly rare abnormalities of chromosome 13 in retinoblastoma cells were discussed in the light of well known data on predisposing role of constitutional deletion 13q14, and recent molecular genetic studies showing the significance of recessive tumour genes in carcinogenesis. The cytological signs of gene amplification (HSRs, DMs) were revealed in few retinoblastomas. However, the recent data on N-myc gene amplification and its elevated expression in several retinoblastomas indicate that amplification of the oncogene(s) might be involved in the genesis of this tumour. Further studies are needed to understand the correlative role of specific chromosome rearrangements, gene(s) amplification and action of recessive rb gene, located at 13q14 in initiation and progression of retinoblastoma.

Molecular hybridization to meiotic chromosomes in man reveals sequence arrangement on the no. 9 chromosome and provides clues to the nature of "parameres".

In situ hybridization of male human meiotic material has been used to elucidate the molecular organization of the centromeric region of human chromosome 9. The use of two cloned DNA sequences has shown that the centromere and the secondary constriction of this chromosome contain two separate repeated DNA families. The secondary constriction organizes into "paramere" bodies during pachytene. The individual parameres are comprised of one family of repeated DNA sequences.

Possible association of a new translocation, t(7;11)(p15;p15), with Ph1 chromosome-negative chronic myelogenous leukemia.

A Ph1 chromosome-negative chronic myelogenous leukemia (CML) with t(7;11)(p15;p15) in a 6-year-old girl is reported. Three cases of 7;11 translocation have been reported so far. The patients concerned were between 37 and 72 years of age; 2 of them had CML and the other had acute myelomonocytic leukemia. Data from these 4 cases suggest that the 7;11 chromosome translocation may be related to a subgroup of Ph1-negative CML, specifically to one that may easily proceed to blast phase, or to "subacute" myelogenous leukemia. The present case demonstrates that CML with this chromosome abnormality is not restricted to adults but also affects children. The t(1;11)(q21 or 23;p15) reported in another case with Ph1-negative CML may be a variant of this translocation.

Fragile sites on human chromosomes: description and clinical significance.

The fragile sites of human chromosomes are specific sites that are characterized by a tendency to show gaps, multiradial figures, acentric fragments, and deleted chromosomes on microscopy. These characteristics seem to reflect an inherent fragility at the site, although the underlying biochemical cause of fragile sites is unknown. Investigators have proposed several categories of fragile sites: "rare" or "heritable," "common," and "constitutive." Although the clinical significance of most fragile sites is unknown, fragile site Xq27.3 is associated with one form of X-linked mental retardation. In this article, the three types of chromosome fragile sites are described, and their possible relevance to chromosomal breakage that results in birth defects or cancer is discussed.