A new mutation in the prion protein gene: a patient with dementia and white matter changes.

The authors describe the clinical characteristics, MRI abnormalities, and molecular findings in a patient with a novel variant of a two-octarepeat insertion mutation in the prion protein gene. This patient presented with moderately progressive dementia of presenile onset and gait ataxia. MRI showed extensive cortical atrophy and white matter abnormalities. The mutation consists of a two-octarepeat insertion mutation and irregularities in the nucleotide sequence of the octarepeat region.

14-3-3 testing in diagnosing Creutzfeldt-Jakob disease: a prospective study in 112 patients.

OBJECTIVE: To study the sensitivity and specificity of 14-3-3 testing in a prospective series of patients suspected of having Creutzfeldt-Jakob disease (CJD). BACKGROUND: The 14-3-3 protein immunoassay on CSF has favorable test characteristics as a premortem diagnostic tool in CJD. However, the 14-3-3 protein is a normal cellular protein expressed in various tissues, and its presence in CSF reflects extensive destruction of brain tissue as in CJD, but also in ischemic stroke and meningoencephalitis. METHODS: 14-3-3 was tested in the CSF of a prospective series of 110 consecutive patients suspected of having CJD. RESULTS: The sensitivity was 97% and the specificity was 87% in this series. False-positive results were mainly caused by stroke and meningoencephalitis. CONCLUSION: The 14-3-3 protein is a highly sensitive and specific marker for CJD when used in the appropriate clinical context.

The gene for the human Src-like adaptor protein (hSLAP) is located within the 64-kb intron of the thyroglobulin gene.

In this study, we describe the molecular cloning and characterization of a Src-like adaptor protein gene embedded within the genomic organization of the human thyroglobulin (Tg) gene. This gene was identified by exon trapping on overlapping cosmids encompassing the largest Tg intron. A 2.6-kb transcript, with the highest levels of expression in fetal brain and lung, was detected on Northern blots. Two full-length cDNAs (one alternatively spliced) were isolated from a fetal brain library, both containing an open reading frame of 276 amino acids, but lacking a catalytic tyrosine kinase domain. The gene shows a high degree of cross-species similarity and appears to be transcribed in the direction opposite to Tg. This gene, designated hslap, appears to be the human ortholog of the recently described gene for the murine Src-like adaptor protein (mSLAP), a candidate intermediate in the signal-transduction pathway of the Eck receptor tyrosine kinase. Human slap is located in the candidate region for a recessive demyelinating neuropathy on chromosome 8q24, but sequence analysis failed to identify mutations, suggesting that it is not the gene for this disease.

[Creutzfeldt-Jakob disease; one year later]. / De ziekte van Creutzfeldt-Jakob; een jaar later.

During the last year the knowledge of the transmission of prion diseases has increased. New diagnostic methods were developed: investigation of cerebrospinal fluid for the 14-3-3 protein and tonsillar biopsy to detect protease resistant prion protein. Indirect evidence of a causal relation between new variant Creutzfeldt-Jakob disease (nvCJ) and bovine spongiform encephalopathy (BSE) is accumulating, although epidemiological data do not indicate that the incidence of CJ is increasing.

Clinically distinct codon 69 mutations in major myelin protein zero in demyelinating neuropathies.

Mutations in the major peripheral myelin protein zero (P0) gene on chromosome 1q21-q23 have been found with the hereditary demyelinating polyneuropathy Charcot-Marie-Tooth type 1B. Here, we describe 2 patients with distinct neurological characteristics, carrying different substitutions at the same codon--Arg69His and Arg69Cys. The patients were heterozygous for the mutation, which in both appeared to be de novo. Histological examination of sural nerve biopsy specimens revealed defective myelin as well as marked differences, confirming the importance of P0 in the compaction of myelin.

Two divergent types of nerve pathology in patients with different P0 mutations in Charcot-Marie-Tooth disease.

In seven unrelated patients with a demyelinating motor and sensory neuropathy, we found mutations in exons 2 and 3 of the P0 gene. Morphologic examination of sural nerve biopsy specimens showed a demyelinating process with onion bulb formation in all cases. In four patients, ultrastructural examination demonstrated uncompacted myelin in 23 to 68% of the myelinated fibers, which is in agreement with the widely accepted function of P0 as a homophilic adhesion molecule. Three patients showed normal compact myelin, but morphology was dominated by the abundant occurrence of focally folded myelin. The two divergent pathologic phenotypes exemplify that some mutations act differently on P0 protein formation or function than others, which is probably determined by site and nature of the mutation in the P0 gene.

Gastric chief cell-specific transcription of the pepsinogen A gene.

The molecular mechanisms underlying the regulation of pepsinogen A (PGA) gene expression in mammalian cells are poorly understood. In this paper we describe the structural and functional analysis of the pepsinogen A gene promoter in the pig. By genomic Southern analyses we demonstrate that, in contrast with human PGA genes which are amplified and organized in haplotypes, only a single PGA gene is present per haploid porcine genome. With the aim of identifying promoter elements mediating the gastric mucosa cell-specific transcription of the PGA gene in pig, we isolated a PGA gene from a porcine genomic library. The nucleotide sequence of the first exon and 1.7 kb of the upstream DNA region were determined and compared with the corresponding regions of the human PGA gene encoding isozymogen Pg5. In order to study the promoter activity of the PGA gene a functional assay was developed: we succeeded in obtaining primary monolayer cultures of porcine gastric mucosal chief cells, suitable for transfection. Fragments of 5'-flanking and noncoding first exon sequences of the porcine and human PGA genes were linked to the chloramphenicol acetyltransferase (CAT) gene. The transcriptional activity of these hybrid genes was assessed in transient expression assays upon transfection (lipofection) of gastric and nongastric cells. Whereas PGA 5'-flanking sequences showed no promoter activity in nongastric cell types, the DNA region from -205 to +21 was found to be sufficient to direct expression of the porcine PGA constructs in a cell-specific manner. Further deletion analysis of the proximal promoter fragment identified several regions (-205 to -167, -127 to -67 and +2 to +21) acting synergistically in the transcriptional regulation of the PGA gene. In contrast, all human PGA-CAT constructs used failed to show promoter activity in porcine gastric chief cells, indicating species-specific control of PGA gene expression. In addition, the transcriptional activity of the porcine PGA promoter in chief cells from pig was completely abolished by in vitro CpG methylation. Footprint analyses of the proximal promoter fragment using nuclear extracts from either porcine gastric mucosal chief cells or liver revealed some notable differences between both extracts, which might reflect the interaction with (a) cell-specific factor(s).