11/161. Molecular basis and enzymatic properties of glucose 6-phosphate dehydrogenase volendam, leading to chronic nonspherocytic anemia, granulocyte dysfunction, and increased susceptibility to infections.We have investigated the blood cells from a woman with a low degree of chronic nonspherocytic hemolytic anemia and frequent bacterial infections accompanied by icterus and anemia. The activity of glucose 6-phosphate dehydrogenase (G6PD) in her red blood cells (RBCs) was below detection level, and in her leukocytes less than 3% of normal. In cultured skin fibroblasts, G6PD activity was approximately 15% of normal, with 4- to 5-fold increased Michaelis constant (Km) for nadp and for glucose 6-phosphate. Activated neutrophils showed a decreased respiratory burst. family studies showed normal G6PD activity in the RBCs from all family members, including both parents and the 2 daughters of the patient. Sequencing of polymerase chain reaction (PCR)-amplified genomic DNA showed a novel, heterozygous 514C-->T mutation, predicting a Pro172-->Ser replacement. Analysis of G6PD rna from the patient's leukocytes and fibroblasts showed only transcripts with the 514C-->T mutation. This was explained by the pattern of X-chromosome inactivation, studied by means of the human androgen receptor (HUMARA) assay, which proved to be skewed in the patient, her mother, and one of the patient's daughters. Thus, the patient has inherited a de novo mutation in G6PD from her father and an X-chromosome inactivation determinant from her mother, causing exclusive expression of the mutated G6PD allele. Purified mutant protein from an escherichia coli expression system showed strongly decreased specific activity, increased Km for nadp and for glucose 6-phosphate, and increased heat lability, which indicates that the defective phenotype is due to 2 synergistic molecular dysfunctions: decreased catalytic efficiency and protein instability.- - - - - - - - - - ranking = 1keywords = protein (Clic here for more details about this article) |
12/161. Mother with amyotrophic lateral sclerosis and daughter with Creutzfeldt-Jakob disease.OBJECTIVE: To describe a mother who had autopsy-proved amyotrophic lateral sclerosis and her daughter who had clinically diagnosed Creutzfeldt-Jakob disease. DESIGN: case reports with molecular genetic analyses. SETTING: A tertiary care center. patients: The mother had progressive upper and lower motor neuron symptoms and signs starting at the age of 54 years. Electrophysiological testing supported the diagnosis of amyotrophic lateral sclerosis. autopsy results confirmed the diagnosis. Her daughter had received injections of human growth hormone prepared from pooled human pituitary glands as a child. At the age of 31 years, she experienced the onset of gait ataxia and dysarthria. cerebrospinal fluid showed the 14-3-3 protein. Cognitive difficulties ensued. She progressed to a nearly akinetic and mute state. She had overt visible fasciculations and muscle atrophy in the legs. MAIN OUTCOME MEASURES AND RESULTS: Neither patient carried a mutation in the prion protein gene. Both were homozygous for methionine at the polymorphic codon 129. Neither patient carried a deletion of the 5 exons of the superoxide dismutase 1 gene. CONCLUSIONS: It is uncertain whether the 2 cases occurred in the same family by chance or whether the patients shared genetic risk factors for the 2 diseases. The possibility that homozygosity at codon 129 is a risk factor for amyotrophic lateral sclerosis is being tested in a case-control study.- - - - - - - - - - ranking = 1keywords = protein (Clic here for more details about this article) |
13/161. Uncompacted myelin in hereditary neuropathy with liability to pressure palsies with the 17 p11.2 deletion.A 16-year-old girl with a typical features of hereditary neuropathy with liability to pressure palsies (HNPP) and deletion on chromosome 17p11.2 was described. In the mother who was asymptomatic the same genetic defect was found. In a sural nerve biopsy obtained from the girl myelin thickenings characteristic for this disease and de- and remyelination in nerve fibers were found. Special attention was paid to the occurrence of uncompacted myelin, which was present in diffuse and focal forms. It is concluded that high amount of uncompacted myelin is characteristic for HNPP and it is probably related to the under-expression of peripheral myelin protein 22.- - - - - - - - - - ranking = 0.5keywords = protein (Clic here for more details about this article) |
14/161. Malignant mesothelioma in subjects with Marfan's syndrome and ehlers-danlos syndrome: only an apparent association?Malignant mesothelioma is a rare neoplasm which could be favored by an hereditary predisposing factor. So far, malignant mesothelioma have never been described in patients with hereditary diseases of the connective tissue. Here, we report some cases of mesothelioma affecting subjects who were not exposed to inhalation of asbestos. One of these subjects was affected by ehlers-danlos syndrome, whereas in two brothers, mesothelioma was associated with Marfan's syndrome. The observation of the same histologic subtype of mesothelioma in two brothers and the coexistence of two pathologic conditions of mesodermal origin indicate the presence of hereditary factors predisposing to the cancerogenic action of even small amounts of asbestos. Structural alterations of collagen and primary immunodeficiency may represent the host factor inducing development of the neoplasm. We conclude that the association between these rare disorders of the connective tissue and mesothelioma may not be coincidental, but could be the result of the exposition to small amounts of asbestos in predisposed individuals.- - - - - - - - - - ranking = 1.0438285392537keywords = deficiency (Clic here for more details about this article) |
15/161. nijmegen breakage syndrome. The International nijmegen breakage syndrome Study Group.BACKGROUND: nijmegen breakage syndrome (NBS) is a rare autosomal recessive disorder. NBS-1, the gene defective in NBS, is located on chromosome 8q21 and has recently been cloned. The gene product, nibrin, is a novel protein, which is member of the hMre11/hRad50 protein complex, suggesting that the gene is involved in DNA double strand break repair. AIMS: To study the clinical and laboratory features of NBS as well as the genotype-phenotype relation. methods: Fifty five patients with NBS, included in the NBS registry in Nijmegen were evaluated. The majority of the patients were of eastern European ancestry. Most of them had shown a truncating 5 bp deletion 657-661 delACAAA. Four further truncating mutations have been identified in patients with other distinct haplotypes. RESULTS AND CONCLUSIONS: Essential features found in NBS were microcephaly, usually without severe retardation, typical facial appearance, immunodeficiency, chromosomal instability, x ray hypersensitivity, and predisposition to malignancy. In 40% of the patients cancer was noted before the age of 21 years. Important additional features were skin abnormalities, particularly cafe au lait spots and vitiligo, and congenital malformations, particularly clinodactyly and syndactyly. Congenital malformations, immunodeficiency, radiation hypersensitivity, and cancer predisposition were comprehensible in case of dysfunctioning of dna repair mechanisms. No specific genotype-phenotype relation could be found. patients with the same genotype may show different phenotypes and patients with different genotypes may express the same phenotype. Specific mutations did not lead to specific clinical features.- - - - - - - - - - ranking = 3.0876570785075keywords = deficiency, protein (Clic here for more details about this article) |
16/161. Familial pulmonary mycobacterium avium complex disease.We report two Japanese families affected by pulmonary mycobacterium avium complex (MAC) disease, involving an older brother and younger sister in one family and two brothers in the second family. We investigated whether defects in the natural resistance-associated macrophage protein gene (NRAMP1) underlay susceptibility to MAC in these cases. All of the patients had computed tomographic findings of peripheral nodules and bronchiectasis. pulse-field gel electrophoresis patterns of mycobacterial genomic DNA restriction fragments revealed that none of the MAC strains isolated from the patients was epidemiologically related to any of the others. Direct sequencing of the complementary DNA of the patients' NRAMP1 revealed a nonconservative missense mutation at codon 419 in one patient, which was heterozygous and was not seen in his affected sibling. No variations similar to those found in mice that show susceptibility to MAC were found. The results suggest an underlying genetic defect in host defense rather than exposure to an unusually virulent strain of MAC as the pathogenetic factor in MAC disease; however, alterations in the coding region of NRAMP1 do not appear to explain the susceptibility to MAC.- - - - - - - - - - ranking = 0.5keywords = protein (Clic here for more details about this article) |
17/161. Familial mitochondrial intestinal pseudo-obstruction and neurogenic bladder.Intestinal dysmotility and neurogenic bladder have been described as part of two autosomal-recessive mitochondrial disorders assumed to be due to a defect in communication between the nuclear and mitochondrial genomes: myoneurogastrointestinal encephalopathy (MNGIE) and diabetes insipidus, diabetes mellitus, optic atrophy, and deafness (wolfram syndrome). Partial cytochrome c oxidase deficiency has been described in both. We describe three Ashkenazi Jewish siblings with progressive intestinal dysmotility, neurogenic bladder, and autonomic manifestations but no central nervous system involvement. Cytochrome c oxidase deficiency was demonstrated in peripheral and multiple intestinal muscle biopsies. Mitochondrial DNA analysis of an intestinal biopsy of patient 1 showed heteroplasmy consisting of a normal 16.5-kb band and an approximately 28-kb band, suggestive of a duplication. Mitochondrial DNA analysis of a muscle biopsy of patient 2 showed multiple deletions, mainly 10- and 11-kb bands. We suggest that this unique combination of intestinal pseudo-obstruction and neurogenic bladder could comprise a new autosomal-recessive mitochondrial disorder.- - - - - - - - - - ranking = 2.0876570785075keywords = deficiency (Clic here for more details about this article) |
18/161. cytomegalovirus infection in infants with autoimmune lymphoproliferative syndrome (ALPS).Fas-mediated apoptosis may be one of the effector pathways leading to the elimination of virus-infected cells. cytomegalovirus (CMV) infection in two brothers with Fas deficiency associated with autoimmunity and benign lymphoproliferation (ALPS) provided a unique opportunity to study the clinical course of CMV infection in children with defective apoptosis. The clinical courses of two brothers with autosomal dominant ALPS who were infected with CMV in the neonatal period are described. CMV was detected from throat and urine culture from the brothers. ALPS was confirmed by in vitro anti-CD95 MoAb-induced T lymphocyte apoptosis assay and subsequent sequencing and identification of mutations in the Fas gene. A de novo mutation in the Fas gene, leading to a truncated cytoplasmic Fas product, was associated with autosomal dominant ALPS in a mother and her two sons. Both boys had evidence of CMV infection acquired early in infancy which cleared by the age of 2-3 years. There were no neurodevelopmental sequelae. The natural history of CMV infection in two infants with ALPS was similar to that described in normal children.- - - - - - - - - - ranking = 1.0438285392537keywords = deficiency (Clic here for more details about this article) |
19/161. A clustering of unfavourable common genetic mutations in stroke cases.OBJECTIVES: The aetiological role of common genetic mutations was analysed in a subgroup of stroke patients. MATERIAL AND methods: A total of 406 patients were examined because of ischaemic stroke. After a detailed clinical scrutiny, 5 were found who did not exhibit any of the classical clinical risk factors. In this clinically homogeneous subgroup of stroke patients, the prothrombin A20210G, hong kong, Cambridge and methylenetetrahydrofolate reductase C677T (MTHFR C677T) mutations, angiotensin-converting enzyme polymorphism (ACE polymorphism) and apolipoprotein E (APO E) genotype were examined. RESULTS: In all 5 patients, the same type of clustering of three mutations was manifested. A heterozygous Leiden V mutation was observed in all 5 subjects, while a heterozygous MTHFR C677T mutation and an I/D genotype for ACE polymorphism were detected in 4 of them, and a homozygous D/D genotype and a homozygous MTHFR C677T mutation in 1. This type of clustering of the mutations was not observed in the remaining 401 stroke patients. CONCLUSION: These results suggest that the Leiden mutation might possibly be an aetiological factor for stroke in a rare subgroup of patients who do not display any of the classical risk factors. The roles of ACE D polymorphism and the MTHFR C677T mutation in stroke, should also be taken into consideration in this subgroup of stroke patients. These unfavourable genetic factors might be aetiological factors if they are clustered together in a stroke patient not presenting any of the standard clinical risk factors.- - - - - - - - - - ranking = 0.5keywords = protein (Clic here for more details about this article) |
20/161. Prolonged survival in hereditary surfactant protein B (SP-B) deficiency associated with a novel splicing mutation.Hereditary surfactant protein B (SP-B) deficiency has been lethal in the first year of life without lung transplantation. We tested the hypothesis that SP-B gene mutations may result in milder phenotypes by investigating the mechanisms for lung disease in two children with less severe symptoms than have been previously observed in SP-B deficiency. Immunostaining patterns for pulmonary surfactant proteins were consistent with SP-B deficiency in both children. DNA sequence analysis indicated that both children were homozygous for a mutation in exon 5 that created an alternative splice site. Reverse transcriptase PCR and sequence analysis confirmed use of this splice site, which resulted in a frameshift and a premature termination codon in exon 7. The predominant reverse transcriptase PCR product, however, lacked exon 7, which restored the reading frame but would not allow translation of the exons that encode mature SP-B. Western blot analysis detected reduced amounts of mature SP-B as well as an aberrant SP-B proprotein that corresponded to the size expected from translation of the abnormal transcript. We conclude that a novel splicing mutation was the cause of lung disease in these children and that hereditary SP-B deficiency can be the cause of lung disease in older children.- - - - - - - - - - ranking = 11.85062831403keywords = deficiency, protein (Clic here for more details about this article) |
| <- Previous || Next -> |