1/95. Familial cerebellar hypoplasia and pancytopenia without chromosomal breakages.Two siblings manifested a neuro-haematologic syndrome characterised by low birth weight, failure to thrive, chronic persistent tongue ulceration, severe truncal ataxia and pancytopenia without either telangiectasia or chromosomal instability. One sibling died from sepsis and the cerebellum demonstrated reduced cellularity of the molecular and granular layers with relative preservation of purkinje cells and minimal gliosis. A surviving sibling has shown haematologic progression to a myelodysplastic disorder. There was no evidence of any chromosomal instability following exposure of fibroblasts and lymphocytes to irradiation. monosomy-7 was not present in the surviving sibling. We suspect that these two patients represent another example of the rare Hoyeraal-Hreidarsson syndrome and we are currently engaged in very close monitoring of the surviving sibling for evidence of any karyotypic abnormality.- - - - - - - - - - ranking = 1keywords = breakage (Clic here for more details about this article) |
2/95. Constitutional chromosomal breakage.There were 18 individuals found to have a constitutional chromosome fragility causing an increase in break frequency. For each chromosome the breakpoint is always the same, whether it involves chromosomes from the same person, the same family, or different families. The fragile points are bands 10q24, 12q13, 16q21, 17p12, and Xq27. Autosomal constitutional fragility does not seem to have a phenotypic correspondence. They were found mostly in parents of children with chromosomal abnormalities or in couples with a history of repeated spontaneous abortions which permits one to raise the possibility of an interchromosomal effect. The six constitutional chromosomal fragilities of the x chromosome had in common the association of mental deficiency, delayed speech, and large malformed ears. The break points in constitutional chromosomal fragility were compared to those of spontaneous breaks in vitro, to those induced by x-rays, and to those in Fanconi's anemia. The theoretical consequences of these structural abnormalities are discussed as well as what to do about them when they are found.- - - - - - - - - - ranking = 1keywords = breakage (Clic here for more details about this article) |
3/95. diagnosis of ataxia telangiectasia with the glycophorin A somatic mutation assay.There are no widely applied definitive laboratory tests for the diagnosis of ataxia telangiectasia (AT). We, and others, have previously reported significantly elevated levels of in vivo somatic mutation in blood samples from known AT patients, observations that might form the basis for a useful prospective laboratory test for confirmation of a clinical diagnosis of AT. In the present case, a 4 1/2-year-old black female was suspected of having AT based on ataxic gait and chronic upper respiratory infections. blood work-up showed low IgG2 and elevated alpha-fetoprotein (AFP), consistent with the AT phenotype. Her peripheral blood karyotype was normal, however, with no spontaneous breakage observed among 100 solid stained metaphases. lymphocytes from AT patients often show elevated levels of chromosome rearrangement, especially at sites of immunoglobulin and T-cell receptor genes. Therefore, a blood sample was analyzed with the glycophorin A (GPA) in vivo somatic mutation assay. The GPA assay detects and quantifies the phenotypically variant erythrocytes resulting from loss of heterozygosity for the MN blood group. The patient had a 10-fold increased frequency of variant erythrocytes with a phenotype consistent with simple loss of the N allele, which is characteristic of AT. In addition, the variant cell distribution for this patient showed three other, more qualitative hallmarks of AT: a normal frequency of allele loss and duplication events, a unique ridge of cells of intermediate phenotype between the normal and mutant peaks, and evidence of similar ongoing mutational loss of the M allele. Together with clinical data, these distinctive qualitative and quantitative features of the GPA assay allow for a diagnosis of AT with a projected accuracy of 95%. Therefore, we suggest that the GPA assay, which can be performed on < 1 ml of blood and completed in less than a day, be considered as a confirmatory laboratory test for a clinical diagnosis of AT.- - - - - - - - - - ranking = 0.25keywords = breakage (Clic here for more details about this article) |
4/95. Chromosomal abnormalities in a series of children with autistic disorder.In a series of 127 children diagnosed with autistic disorder the karyotypes of 8, on whom data were available, showed the following chromosomal abnormalities: breakage, a 47 XY pattern, trisomy 13, inversion-duplication of chromosome 15, 47 XY, der (15) (pter q15: p11 pter), 47 XXY and 46 XY, inv (2) (p11:q13pat, 3q ). Compared to those who were not karyotyped or had normal karyotypes, the children with abnormalities, although cognitively more delayed, were not rated as more severely autistic. Facial dysmorphias and minor physical anomalies tended to be more frequent in the chromosomally deviant subgroup. No differences in demographic characteristics or parental ages were evident. Results are consistent with the view of variability of expression of marker chromosome deviations and a greater severity of retardation and symptoms of autism in those affected. The relevance of the findings to a multimodal genetic etiology of autistic disorder is discussed.- - - - - - - - - - ranking = 0.25keywords = breakage (Clic here for more details about this article) |
5/95. Karyotypic analyses of hepatoblastoma. Report of two cases and review of the literature suggesting chromosomal loci responsible for the pathogenesis of this disease.Two cases of fetal hepatoblastoma with unique karyotypic changes are described. One was a 17-month-old boy with multiple unbalanced chromosomal translocations, resulting in four types of derivative chromosomes involving chromosomal loci at 1q21, 1q32, 2q23, 6q27, 7p22, and 21p12, partial tetrasomy of 1q, partial trisomy of 2q, and partial monosomy of 21p. The clonal karyotype of this tumor was 46,XY,der(2)t(1;2)(q32;q37), der(6)t(1;6)(q12;q27), der(7)t(2;7)(q23;p22), der(21)t(2;21) (q23;p12). In the other case, a 4-year-old girl, karyotypic analyses revealed trisomy 2 and 8, and the clonal karyotype of this case was 48,XX, 2, 8. review of these cases together with previous reports suggested the significance of chromosomal changes including numerical abnormalities of 1q, 2(or 2q), 20, and 8 (or 8q), and breakage of 1q and 2q in the development of hepatoblastoma. The results presented herein underscore the significance of numerical abnormalities of chromosomal regions 1q and 2q and of chromosome 8 in the development of hepatoblastoma, in addition to abnormalities of 6q27, 7p22, and 21p12-13 as other chromosomal loci that may be responsible for the pathogenesis of this embryonal type of tumor.- - - - - - - - - - ranking = 0.25keywords = breakage (Clic here for more details about this article) |
6/95. Two complex translocations in chronic granulocytic leukemia involving chromosomes 22, 9, and a third chromosome.Among 13 Ph-positive cases of chronic granulocytic leukemia (CGL), banding studies revealed two with complex rearrangements involving translocation of the long arm of number 22 to another autosome and a segment of that chromosome translocated to the long arm of number 9. In a patient with both CGL and sickle cell anemia, the 3-way rearrangement involved chromosomes 5, 9, and 22; and he also had a second philadelphia chromosome and two constitutional variants: pericentric inversion of the other number 9 chromosome and satellite polymorphism in the G group. The karyotype of the leukemic cells was interpreted as: 47,XY,inv(9) (p11q13),t(5;9;22)(q13;q34;q11) del(22)(q11). In the second patient, the complex translocation in the Ph-positive cells involved chromosomes 3, 9, and 22, resulting in a karyotype interpreted as: 46,XX,t(3;9;22)(p21;q34;q11). Several reports indicate that an abnormality of chromosome 9 is not essential for the development of Ph-positive CGL, but the very high frequency of its involvement (including these unusual translocations) suggests that some type of non-random somatic association may exist between 9q and 22q which makes simultaneous breakage likely. Attempts to correlate specific types of pH chromosome rearrangements with the clinical course of CGL must await the identification of more cases and longer follow-up.- - - - - - - - - - ranking = 0.25keywords = breakage (Clic here for more details about this article) |
7/95. A new translocation in chronic myelogenous leukemia.A reciprocal translocation involving chromosomes Nos. 3 and 22 has been found in a patient with seemingly Ph-negative chronic myelogenous leukemia (CML). G-band analysis revealed, that deletion in No. 22 occurred at the same point, as in the typical cases of the disease. It was concluded, that breakage in No. 22 at a specific site with spatial disjunction of the resulting segments might be the crucial cytogenetic event in the genesis of CML, the philadelphia chromosome not being an obligatory result of the rearrangement.- - - - - - - - - - ranking = 0.25keywords = breakage (Clic here for more details about this article) |
8/95. Japanese family with an autosomal dominant chromosome instability syndrome: a new neurodegenerative disease?We report on a Japanese family having an autosomal dominant neurodegenerative disease with chromosomal instability and radiosensitivity. Clinical manifestations of affected members included short stature, osteoporosis, severe dental caries, and various neurological abnormalities, such as mental retardation, depression, dysarthria, hyperreflexia, and ataxic gait. MRI demonstrated a markedly atrophic spinal cord and degeneration of the white matter. Cytogenetic examination showed spontaneous chromosome rearrangements at 14q11.2 and hypersensitivity to radiation and bleomycin. The degree of these cytogenetic abnormalities was significantly higher in the patients than in normal controls but lower than in patients with ataxia telangiectasia or nijmegen breakage syndrome. Moreover, genetic anticipation was observed in this family: the age of disease onset became earlier, MRI abnormalities more extensive, and the chromosome hypersensitivity to radiation increased in successive generations. We speculate that a basic defect in this family is a mutation in the gene that is responsible for dna double-strand breakage repair.- - - - - - - - - - ranking = 1.21408354986keywords = breakage syndrome, breakage (Clic here for more details about this article) |
9/95. Combined immunodeficiency, chromosomal instability, and postnatal growth deficiency in a Japanese girl.We report on an 11-year-old Japanese girl with combined immunodeficiency and chromosomal instability. She had postnatal growth deficiency and microcephaly, preaxial polydactyly of the left hand, and susceptibility to infections. Immunological studies showed marked lymphocytopenia (around 500/ll), reduced lymphocyte response to various mitogens, and reduced or absent serum IgA, IgG, and IgM. Cell biological studies of her primary skin fibroblasts demonstrated spontaneous chromosome aberrations and radiation hypersensitivity. The combination of immunodeficiency, chromosomal instability, and radiation hypersensitivity as seen in the girl is present in both ataxia-telangiectasia and nijmegen breakage syndrome. Ataxia-telangiectasia was excluded because of differences in clinical features and laboratory data. Likewise, nijmegen breakage syndrome is unlikely to be the case because the characteristic face, hyperpigmented spots, and mental retardation present in the syndrome were missing in the girl. sequence analysis of a nijmegen breakage syndrome responsible gene, NBS1, revealed no mutations. A normal NBS1 product was also demonstrated by immunoblot analysis using an anti-NBS1 antibody. We propose that the disorder in the girl represents a new combination of combined immunodeficiency and chromosomal instability.- - - - - - - - - - ranking = 2.8922506495799keywords = breakage syndrome, breakage (Clic here for more details about this article) |
10/95. Familial erythromelanosis follicularis and chromosomal instability.We report a 17-year-old male patient with erythromelanosis follicularis faciei et colli (EFFC), oral leucokeratosis and diabetes mellitus without islet cell antibody. His sister also had minimal findings of EFFC and minimal follicular papules on her shoulders and extensor surfaces of the arms. The father had only fine follicular papules, but no erythromelanosis. skin and mucous membrane lesions of the proband were investigated histopathologically. Interestingly, in peripheral lymphocyte cultures of the family members, chromosomal breakage was not observed spontaneously, but it was seen with nitrogen mustard, although this disease may be of autosomal recessive inheritance. Thus, we suggest that EFFC may be a polyaetiological disorder (i.e. familial and environmental) and might be considered one of the chromosomal instability syndromes.- - - - - - - - - - ranking = 0.25keywords = breakage (Clic here for more details about this article) |
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