RESUMO
We have collated the results of cystic fibrosis (CF) mutation analysis conducted in 19 laboratories in France. We have analyzed 7, 420 CF alleles, demonstrating a total of 310 different mutations including 24 not reported previously, accounting for 93.56% of CF genes. The most common were F508del (67.18%; range 61-80), G542X (2.86%; range 1-6.7%), N1303K (2.10%; range 0.75-4.6%), and 1717-1G>A (1.31%; range 0-2.8%). Only 11 mutations had relative frequencies >0. 4%, 140 mutations were found on a small number of CF alleles (from 29 to two), and 154 were unique. These data show a clear geographical and/or ethnic variation in the distribution of the most common CF mutations. This spectrum of CF mutations, the largest ever reported in one country, has generated 481 different genotypes. We also investigated a cohort of 800 French men with congenital bilateral absence of the vas deferens (CBAVD) and identified a total of 137 different CFTR mutations. Screening for the most common CF defects in addition to assessment for IVS8-5T allowed us to detect two mutations in 47.63% and one in 24.63% of CBAVD patients. In a subset of 327 CBAVD men who were more extensively investigated through the scanning of coding/flanking sequences, 516 of 654 (78. 90%) alleles were identified, with 15.90% and 70.95% of patients carrying one or two mutations, respectively, and only 13.15% without any detectable CFTR abnormality. The distribution of genotypes, classified according to the expected effect of their mutations on CFTR protein, clearly differed between both populations. CF patients had two severe mutations (87.77%) or one severe and one mild/variable mutation (11.33%), whereas CBAVD men had either a severe and a mild/variable (87.89%) or two mild/variable (11.57%) mutations.
Assuntos
Regulador de Condutância Transmembrana em Fibrose Cística/genética , Fibrose Cística/epidemiologia , Fibrose Cística/genética , Mutação/genética , Ducto Deferente/anormalidades , Adulto , Alelos , Deleção Cromossômica , Mutação da Fase de Leitura/genética , França/epidemiologia , Frequência do Gene , Genótipo , Humanos , Infertilidade Masculina/epidemiologia , Infertilidade Masculina/genética , Masculino , Pessoa de Meia-Idade , Mutagênese Insercional/genética , Mutação de Sentido Incorreto/genética , Polimorfismo Genético/genéticaRESUMO
De novo methylation of the 5'CpG island has been recently reported as an alternative mechanism of inactivation for the tumour suppressor genes CDKN2A and CDKN2B. We examined CDKN2A methylation status at diagnosis in 42 B-cell chronic lymphocytic leukaemia (CLL) patients, in 19 cases the CDKN2B methylation status was also analysed. No homozygous CDKN2A/2B deletion was detected, but four patients (9%) displayed an aberrant CDKN2A methylation status and only one had hypermethylated CDKN2B. De novo methylation was associated with silencing of gene expression. These results confirm that CDKN2A/2B inactivation by deletion is a rare event in CLL and suggest that aberrant methylation could be an alternative way of inactivation very rarely involved in the development of some CLL.
Assuntos
Inibidor p16 de Quinase Dependente de Ciclina/genética , Genes Supressores de Tumor , Leucemia Linfocítica Crônica de Células B/genética , Southern Blotting , Deleção de Genes , Humanos , Metilação , Reação em Cadeia da PolimeraseRESUMO
Magnesium-dependent hypocalcaemia (HSH), a rare inherited disease, is caused by selective disorders of magnesium absorption. Both X-linked and autosomal recessive modes of inheritance have been reported for HSH; this suggests a genetically heterogeneous condition. A balanced de novo t(X;9)(p22;q12) translocation has been reported in a female manifesting hypomagnesemia with secondary hypocalcemia. In a lymphoblastoid cell line, derived from this patient, the normal X chromosome is preferentially inactivated, suggesting that the patient's phenotype is caused by disruption of an HSH gene in Xp22. In an attempt to define more precisely the position of the X breakpoint, we have constructed a hybrid cell line retaining the der(X)(Xqter-Xp22.2::9q12-9qter) in the absence of the der(9) and the normal X chromosome. Southern blot analysis of this hybrid and in situ hybridization on metaphase chromosomes have localized the breakpoint between DXS16 and the cluster (DXS207, DXS43), in Xp22.2. Thus, if a gene involved in HSH residues at or near the translocation breakpoint, our findings should greatly facilitate its isolation.
Assuntos
Cromossomos Humanos Par 9 , Hipocalcemia/genética , Deficiência de Magnésio/genética , Translocação Genética , Cromossomo X , Southern Blotting , Transformação Celular Viral , Aberrações Cromossômicas , Mapeamento Cromossômico , Feminino , Humanos , Hipocalcemia/complicações , Hibridização In Situ , Deficiência de Magnésio/complicaçõesRESUMO
67 patients with Noonan syndrome seen over the last 29 years were selected preferentially on cardiac involvement. The cardiac anomalies consisted in the association of dysplastic pulmonary stenosis with asymmetric cardiomyopathy. In one patient, a translocation (3;22) was found. The relationship with cardio-facio-cutaneous syndrome and with the group of phacomatoses is discussed. The familial occurrence (10 families) seems compatible with autosomal dominant inheritance. A gene location on chromosome 22 cannot be excluded.
Assuntos
Cromossomos Humanos Par 22 , Cromossomos Humanos Par 3 , Cardiopatias Congênitas , Síndrome de Noonan/genética , Adolescente , Adulto , Osso e Ossos/anormalidades , Criança , Pré-Escolar , Face/anormalidades , Feminino , Genes Dominantes , Humanos , Lactente , Linfedema/genética , Masculino , Pessoa de Meia-Idade , Síndrome de Noonan/diagnóstico , Síndrome de Noonan/patologia , Fenótipo , Dermatopatias/genética , Crânio/anormalidades , Translocação GenéticaRESUMO
The myristoylated, alanine-rich C-kinase substrate, or MARCKS protein, is a major cellular substrate for protein kinase C that is also a high-affinity calmodulin-binding protein. In addition, it is the prototype of a small family of myristoylated, calmodulin-binding protein kinase C substrate proteins. We isolated a phage clone from a mouse genomic library that spanned the entire coding sequence of the mouse MARCKS protein. The first 612 bp of the putative promoter was 89% identical to a corresponding region of the human promoter, and contained at least 59 potential transcription factor binding sites in analogous locations; both human and mouse promoters lacked TATA boxes. The mouse genomic probe was used to localize the mouse gene to chromosome 10, in the middle of a linkage group that corresponds to a region on human chromosome 6q. These data strongly suggested that the human gene would localize to 6q21. This was confirmed by studies of DNA from a patient with del(6)(q21), in which expression of the human gene encoding MARCKS, MACS, was only about 50% of normal; MARCKS mRNA expression in lymphoblast RNA from this patient was only 22% of normal. These studies confirm that the mouse and human MARCKS proteins are products of the same genes in their respective species; differences in their primary sequence can therefore be attributed to species variation rather than to the existence of related genes.
Assuntos
Mapeamento Cromossômico , Peptídeos e Proteínas de Sinalização Intracelular , Proteínas de Membrana , Proteínas/genética , Animais , Sítios de Ligação Microbiológicos , Sequência de Bases , Northern Blotting , Southern Blotting , Cromossomos Humanos Par 6 , Clonagem Molecular , Ligação Genética , Humanos , Camundongos , Camundongos Endogâmicos C3H , Dados de Sequência Molecular , Muridae , Substrato Quinase C Rico em Alanina Miristoilada , Regiões Promotoras Genéticas/genética , Proteínas Proto-Oncogênicas/genética , Proteínas Proto-Oncogênicas c-fyn , Proteínas Proto-Oncogênicas c-myb , Proteínas Proto-Oncogênicas c-raf , Homologia de SequênciaRESUMO
A specific translocation between chromosomes X and 18 was identified in synovial sarcomas. From a girl with synovial sarcoma, we isolated two clones with t(X; 18)(p11.2; q11.2) and which had lost the normal X chromosome. Southern blot analysis of DNA from the tumor, the patient and her parents demonstrated that the normal X chromosome, lost in the tumor, was the paternal one. A somatic hybrid cell line was established by fusing tumor cells (after passages on athymic mice) to an HPRT deficient hamster cell line. By cytogenetic, in situ hybridization and molecular analysis, it was found to contain the derivative (X) chromosome in the absence of the der (18) chromosome. To determine the position of the breakpoint on the X chromosome, Southern blots of DNA from this hybrid were hybridized to [32P]-labelled X chromosome probes. DXS146 and DXS255 were retained in the hybrid cell line whereas GAPDP1, the ARAF1 and TIMP proto-oncogenes were not present, indicating that the breakpoint lies proximal to GAPD1, ARAF1 and TIMP and distal to DXS255 and DXS146. Results obtained from other authors are compared. Further studies will be necessary to determine the extent of variation of the breakpoint in different tumors.
Assuntos
Cromossomos Humanos Par 18 , Sarcoma Sinovial/genética , Translocação Genética , Cromossomo X , Southern Blotting , Mapeamento Cromossômico , Mecanismo Genético de Compensação de Dose , Humanos , LinhagemRESUMO
A direct bioluminescence assay for bacteriuria screening is described and compared with the MS-2 system (Abbott Laboratories, Irvine, Tex.) and the chemical strip, Gram smear, and calibrated-loop methods. A total of 973 specimens were tested. Unlike previously described bioluminescence methods, this test measures total ATP in urine without pretreatment of samples to remove somatic ATP. The result was compared with an ATP standard (20 ng/ml). A low result (less than 3% of standard) was interpreted as negative and a high result (greater than 10% of standard) as positive. Samples with intermediate results (38% of total) were incubated at 35 degrees C in thioglycolate broth (1:10). A 2% increase in ATP concentration was interpreted as positive. The sensitivity of this method for detecting greater than 10(5) pathogens per ml was 92.3% and was comparable to those of the MS-2 system (92.7%) and the Gram smear method (90.5%). The chemical strip method was less sensitive (84.0%). The direct bioluminescence method was more sensitive than were the MS-2 system and the Gram smear method for detecting low-level bacteriuria (less than 10(3) to 10(5) organisms per ml), primarily because of associated pyuria. Thioglycolate broth provided a suitable medium for ATP production, and 5% CO2 decreased bacterial ATP synthesis during log-phase growth. The direct bioluminescence assay is rapid, simple, cost-effective, and reliable for bacteriuria screening.