RESUMO
First described in 1971, partial trisomy 6p is uncommon and generally secondary to a familial reciprocal translocation. The proximal breakpoint of the reported cases varies from p11 to p25. We here report on a patient with moderate mental retardation, craniofacial and pigmentary anomalies, proteinuria, and hyperglycemia who was found to have a mosaic karyotype 46,X,add(Y)(q12)/45,X. Fluorescence in situ hybridization (FISH) enabled us to identify that the additional material on Yqh derived from 6p and to define the rearrangement as der(Y)t(Y;6)(q12;p22). To the best of our knowledge, this is the first case of trisomy 6p22-pter without an associated deleted segment; the second breakpoint of the rearrangement is in Yqh. Precise mapping of the centromeric breakpoint of the trisomic 6p segment allowed a more convincing correlation between partial 6p trisomy and clinical phenotype to be addressed. In particular, the proteinuria often observed in 6p trisomic patients could be assigned to the 6p22-6pter region.
Assuntos
Cromossomos Humanos Par 6 , Trissomia , Genótipo , Humanos , Hibridização in Situ Fluorescente , Cariotipagem , Masculino , Fenótipo , Translocação Genética , Cromossomo YRESUMO
We report a male infant with a de novo inverted duplication of bands 8p 21.1----22.1. The clinical features up to 8 months of age and the enzyme investigations are described. A new cytogenetic hypothesis on the genesis of this rare chromosome aberration is also discussed.
Assuntos
Aberrações Cromossômicas/genética , Cromossomos Humanos Par 8 , Trissomia , Bandeamento Cromossômico , Deleção Cromossômica , Transtornos Cromossômicos , Glutationa Redutase/sangue , Humanos , Recém-Nascido , Masculino , MutaçãoRESUMO
We report on a newborn girl with a terminal deletion of the long arm of chromosome 10: del (10)(pter----q26). The phenotypic manifestations are compatible with those of the previously reported cases. In addition, the association with abnormalities of the urinary tract is reported for the first time. A clinical and neurodevelopmental follow-up is described up to age 18 months.
Assuntos
Aberrações Cromossômicas/diagnóstico , Deleção Cromossômica , Cromossomos Humanos Par 10 , Bandeamento Cromossômico , Transtornos Cromossômicos , Expressão Facial , Feminino , Cardiopatias Congênitas/genética , Humanos , Lactente , Sistema Urinário/anormalidadesRESUMO
Three cases of deletion of the short arm of chromosome 5 are described: one family cluster, in which the mother and three sons are affected, and two sporadics without the typical "cri du chat" phenotype (the family and Case 2 were previously reported in 1982). Mental retardation varied between affected members of the same family. Band p15.2 appears critical for the development of the complete phenotype. A peculiar deafness observed in the familial and one of the sporadic cases suggests a cochlear malformation.
Assuntos
Deleção Cromossômica , Cromossomos Humanos Par 5 , Síndrome de Cri-du-Chat/genética , Adolescente , Adulto , Criança , Mapeamento Cromossômico , Feminino , Humanos , Cariotipagem , MasculinoRESUMO
Chromosome analysis in a 31-year-old woman referred for primary amenorrhea, revealed a very high incidence of chromosome aberrations. She had microcephaly and immunodeficiency. Her healthy parents were consanguineous (1/32) and a younger sister, also with primary amenorrhea, died when 20 years old with a malignant lymphoma. Chromosome studies were performed on lymphocytes and fibroblasts and in both tissues a high proportion of metaphases with multiple chromosome aberrations was found. Clonal and sporadic rearrangements, consisting of balanced and unbalanced translocations and dicentric chromosomes were more numerous than chromatid and chromosome breaks. In the lymphocytes the same unbalanced translocation t(8q;21q) was present in about 59% of the metaphases. Rearrangements involving chromosomes 7 and 14, similar to those described in patients with ataxia-telangiectasia were found, but with a lower frequency. Sister Chromatid Exchanges were not increased. Chromosome and chromatid abnormalities were enhanced after exposure of cells to mitomycin C but not after exposure to the radiomimetic drug bleomycin. Clinical and cytogenetic characteristics of the patient are compared with those of syndromes (Ataxia-Telangiectasia and Werner's syndrome) or isolated cases (Weemaes et al. 1981, Sperling 1983, Spinner et al. 1985) whose features are similar to those of our patient. This case might represent a new chromosome instability syndrome due to a recessive mutation.
Assuntos
Amenorreia/genética , Aberrações Cromossômicas , Síndromes de Imunodeficiência/genética , Microcefalia/genética , Adulto , Cromossomos Humanos Par 14 , Cromossomos Humanos Par 21 , Cromossomos Humanos Par 7 , Cromossomos Humanos Par 8 , Consanguinidade , Feminino , Genes Recessivos , Humanos , Síndrome , Translocação GenéticaRESUMO
If a ring 21, originating from breaks close to the telomere of 21q and anywhere in 21p, replaces a normal 21, it may be associated with an apparently normal phenotype. An apparently normal mother and son were ascertained by a prenatal chromosome study. A second mother, with a ring 21 but without gross anomalies, is short of stature, has epilepsy and has a low normal intelligence. He daughter is a mosaic: 46,XX/47,XX,+r(21) and has the Down's syndrome. None of these four persons was found to have mitoses with more than one ring 21 or with rings of double size.
Assuntos
Aberrações Cromossômicas , Cromossomos Humanos 21-22 e Y , Síndrome de Down/genética , Fenótipo , Adulto , Criança , Dermatoglifia , Epilepsia/genética , Feminino , Humanos , Recém-Nascido , Itália , Masculino , Mosaicismo , Linhagem , SuíçaRESUMO
Following a previous collaborative study (Fraccaro et al. 1980), 20 new cases of 11q;22q translocation are described. Twelve families were ascertained through an unbalanced carrier of the translocation and eight cases were ascertained as balanced carriers. A segregation analysis was performed on the 110 families so far published. It was concluded that the 11q;22q translocation is a relatively frequent event, and that all the cases thus far reported might have the same breakpoints at 11q23.3 and 22q11.2. The translocation seems to be independent of environmental factors and it seems to have a low rate of mutation as indicated by the scarcity of de novo cases. The new data confirmed that only one type of unbalanced karyotype (47,XX or XY+der(22)t(11;22)(q23.3;q11.2)) is found among the offspring of the translocation carriers. The minimal overall recurrence risk for an unbalanced translocation was estimated to 2%. There was no difference between the recurrence risks for male and female balanced carriers, while the trend was confirmed of an excess of female balanced carriers among the phenotypically normal offspring of the t(11;22) female carriers.
Assuntos
Anormalidades Múltiplas/genética , Cromossomos Humanos 21-22 e Y , Cromossomos Humanos 6-12 e X , Deficiência Intelectual/genética , Translocação Genética , Adolescente , Criança , Pré-Escolar , Meio Ambiente , Feminino , Frequência do Gene , Heterozigoto , Humanos , Lactente , Recém-Nascido , Cariotipagem , Masculino , Mutação , Linhagem , Fenótipo , Recidiva , RiscoRESUMO
Seven patients are described who have some or all of the symptoms of Prader-Willi syndrome. They were ascertained by varying criteria starting either from the clinical picture or from the identification of a chromosome abnormality involving the proximal portion of the long arm of chromosome 15. The chromosome abnormalities consisted of two balanced translocations (15;18 and 8;15), three unbalanced ones (15;18, 15;19, and 9;15), and one interstitial deletion of bands 15q11 and q12. The seventh case had an unidentified extra chromosome. These data and a review of the literature led to the conclusion that deficiency, transposition, and even duplication of the region(s) 15q11-q13 may all result in a syndrome which is identifiable with or similar to the Prader-Willi syndrome.