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Query: UMLS:C0027066 (myoclonus)
 4,275 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Genetic linkage analysis shows that Baltic and Mediterranean myoclonus, two forms of progressive myoclonus epilepsy, are closely linked to marker D21S113 on the long arm of chromosome 21. Baltic and Mediterranean myoclonus are most probably due to mutations of the same gene.
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PMID:Identical genetic locus for Baltic and Mediterranean myoclonus. 134 5

The progressive myoclonus epilepsies (PME) are a heterogeneous group of rare genetic disorders. Unverricht-Lundborg disease and Lafora's disease are two major classic forms of PME. We recently assigned the gene for Unverricht-Lundborg disease (EPM1) to human chromosome 21 band q22.3. We have now refined the localization of EPM1 by linkage analysis between the disease phenotype and nine DNA markers in 13 Finnish families. Loci MX1 and CD18 flank the EPM1 interval, which spans a distance of about 3.5 megabases. In this 20-centimorgan interval, no recombinations were detected between EPM1 and marker loci BCEI, D21S19, D21S42, D21S113, D21S154, and PFKL. Within this interval a maximum multipoint lod score of 11.04 was reached at loci D21S154-PFKL. In two Swedish families with Unverricht-Lundborg disease no recombinations were detected. In three Italian families with Lafora's disease the linkage results suggested that EPM1 is not the locus for Lafora's disease.
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PMID:Linkage studies in progressive myoclonus epilepsy: Unverricht-Lundborg and Lafora's diseases. 164 Nov 51

Progressive myoclonus epilepsy of Univerricht-Lundborg type is a clinically defined entity among the progressive myoclonus epilepsies. It is an autosomal recessive disorder. The underlying biochemical defect is unknown. We used linkage analysis to localize the gene in 12 families with the aid of polymorphic DNA markers. Close linkage was detected with three markers on distal chromosome 21. The loci BCEI and D21S154 gave the highest positive logarithm-of-odds (lod) scores of 5.49 and 4.25, respectively, at zero recombination. The third locus, D21S112, gave a lod score of 6.91 at a recombination fraction of 0.034. There was no evidence of heterogeneity. Multipoint lod scores calculated against a fixed map of the three marker loci gave a maximum four-point lod score of 10.08 at a location of the disease gene at 6.0 centimorgans distal to locus BCEI and 0.8 centimorgan proximal to locus D21S154. As markers BCEI and D21S154 have previously been localized to 21q22.3 by physical methods, our findings place the EMP1 gene locus (for progressive myoclonus epilepsy of the Unverricht-Lundborg type) in chromosome 21 band q22.3. This finding provides an opportunity to test several other epilepsy phenotypes, particularly the so-called Ramsay Hunt syndrome, for linkage to the same locus. It also is a starting point toward isolating and characterizing the gene and its protein product.
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PMID:Localization of a gene for progressive myoclonus epilepsy to chromosome 21q22. 167 90

We report the clinical and neuropathological manifestations of Alzheimer's disease (AD) in nine kindreds of German ancestry all originating from the same two adjacent villages on the West bank of the Volga River. There have been 89 known demented persons (53 male, 36 female). Mean age of onset is 57.6 +/- 8.4 years with a range of 40 to 84. Mean age at death is 66.5 +/- 7.6 years with a range of 50 to 80. Mean disease duration is 10.3 +/- 4.8 years with a range of 3 to 23. Detailed medical records were available on 50 individuals. Of these, 24% had a seizure, 72% language disturbance, 36% rigidity, 16% tremor and 12% myoclonus. There were 15 autopsies on demented persons from 6 of the kindreds. One brain suggested Creutzfeldt-Jakob disease (CJD) in a woman with the typical clinical course. The remaining 14 brains showed typical neuropathological characteristics of AD including neuritic amyloid plaques, neurofibrillary tangles, amyloid angiopathy and granulovacuolar change. Amyloid plaques were also seen in the cerebellum in all but one brain in which this region was available for review. Autopsy material from five brains in four families has been stained with antibody directed against the amyloid peptide; in all cases, the neuritic plaques stained positively. Many of the families share common surnames. It is likely that these Volga German kindreds carry the same genetic mutation leading to Alzheimer's disease; and thus, they are a valuable resource for genetic investigations of AD. Thus far, the disease in these kindreds does not show close linkage to either the D21S1 or beta amyloid gene loci on chromosome 21.
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PMID:Characteristics of familial Alzheimer's disease in nine kindreds of Volga German ancestry. 260 19

The clinical and biological features of Alzheimer disease are not uniform in their expression; heterogeneity is evident in the disease's clinical, anatomic, and physiologic characteristics. The presence of considerable intersubject and intrasubject heterogeneity suggests that subtypes of the disease exist. We define subtypes of Alzheimer disease in regard to the behavioral features (for example, predominant right or left hemisphere, or symmetrical impairment), inheritance (familial or sporadic), dosage of chromosome 21 (presence of the Down syndrome), time course of progression, age of onset (presenile or senile), and presence or absence of motor deficit (myoclonus or signs of an extrapyramidal syndrome). Studies of regional cerebral glucose metabolism with positron emission tomography and [18-fluorine] fluorodeoxyglucose show focal alterations in glucose use, with cerebral metabolic asymmetries in patients with Alzheimer disease that are related to the nature of the cognitive deficit. Serial roentgenographic computed tomographic studies show heterogeneous rates of lateral ventricle enlargement in the disease that are related to rates of cognitive decline. Similar anatomic and physiologic abnormalities are also found in persons 45 years of age or older who have the Down syndrome. Furthermore, patients with Alzheimer disease who have extrapyramidal dysfunction or myoclonus are a distinct subgroup, with specific abnormalities of central monoamine markers of dopamine metabolism, serotonin metabolism, and the hydroxylation cofactor, biopterin. The concept of subtypes in Alzheimer disease serves as a model with which the interactions of genetic influences with environmental factors can be examined.
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PMID:NIH conference. Alzheimer disease: clinical and biological heterogeneity. 296 3

The construction of a transcriptional map for human chromosome 21 requires the generation of a specific catalogue of genes, together with corresponding mapping information. Towards this goal, we conducted a pilot study on a pool of random chromosome 21 cosmids representing 2 Mb of non-contiguous DNA. Exon-amplification and cDNA selection methods were used in combination to extract the coding content from these cosmids, and to derive expressed sequences libraries. These libraries and the source cosmid library were arrayed at high density for hybridisation screening. A strategy was used which related data obtained by multiple hybridisations of clones originating from one library, screened against the other libraries. In this way, it was possible to integrate the information with the physical map and to compare the gene recovery rate of each technique. cDNAs and exons were grouped into bins delineated by EcoRI cosmid fragments, and a subset of 91 cDNAs and 29 exons have been sequenced. These sequences defined 79 non-overlapping potential coding segments distributed in 24 transcriptional units, which were mapped along 21q. Northern blot analysis performed for a subset of cDNAs indicated the existence of a cognate transcript. Comparison to databases indicated three segments matching to known chromosome 21 genes: PFKL, COL6A1 and S100B and six segments matching to unmapped anonymous expressed sequence tags (ESTs). At the translated nucleotide level, strong homologies to known proteins were found with ATP-binding transporters of the ABC family and the dihydroorotase domain of pyrimidine synthetases. These data strongly suggest that bona fide partial genes have been isolated. Several of the newly isolated transcriptional units map to clinically important regions, in particular those involved in Down's syndrome, progressive myoclonus epilepsia and auto-immune polyglandular disease. The study presented here illustrates the complementarity of exon-amplification and cDNA selection techniques for generating a large resource of new expressed landmarks, which contribute to the construction of a chromosome 21 transcript map.
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PMID:Model for a transcript map of human chromosome 21: isolation of new coding sequences from exon and enriched cDNA libraries. 758 66

Seven phenotypically homogeneous Mediterranean myoclonus families were studied using DNA markers from the genetically defined EPM1 region on chromosome 21. No recombinations between the disease phenotype and the markers studied were detected. Within the EPM1 region, the highest lod score value of 5.07 (at theta = 0.00) was reached at locus PFKL. Significant allelic association (P = 0.02) between the disease mutation and PFKL was detected suggesting a founder effect in Mediterranean myoclonus. However, haplotype data using four marker loci residing within 300 kb of each other and of EPM1 suggest the occurrence of more than one mutation. The data are compatible with Mediterranean myoclonus being caused by mutations in the EPM1 gene and strengthen the concept that a large subset of progressive myoclonus epilepsies conforms with Unverricht-Lundborg disease and that this subset is an etiologically homogeneous entity.
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PMID:PME of Unverricht-Lundborg type in the Mediterranean region: linkage and linkage disequilibrium confirm the assignment to the EPM1 locus. 800 91

The chromosomal loci for seven epilepsy genes have been identified in chromosomes 1q, 6p, 8q, 16p, 20q, 21q, and 22q. In 1987, the first epilepsy locus was mapped in a common benign idiopathic generalized epilepsy syndrome, juvenile myoclonic epilepsy (JME). Properdin factor or Bf, human leukocyte antigen (HLA), and DNA markers in the HLA-DQ region were genetically linked to JME and the locus, named EJM1, was assigned to the short arm of chromosome 6. Our latest studies, as well as those by Whitehouse et al., show that not all families with JME have their genetic locus in chromosome 6p, and that childhood absence epilepsy does not map to the same EJM1 locus. Recent results, therefore, favor genetic heterogeneity for JME and for the common idiopathic generalized epilepsies. Heterogeneity also exists in benign familial neonatal convulsions, a rare form of idiopathic generalized epilepsy. Two loci are now recognized; one in chromosome 20q (EBN1) and another in chromosome 8q. Heterogeneity also exists for the broad group of debilitating and often fatal progressive myoclonus epilepsies (PME). The gene locus (EPM1) for both the Baltic and Mediterranean types of PME or Unverricht-Lundborg disease is the same and is located in the long arm of chromosome 21. Lafora type of PME does not map to the same EPM1 locus in chromosome 21. PME can be caused by the juvenile type of Gaucher's disease, which maps to chromosome 1q, by the juvenile type of neuronal ceroid lipofuscinoses (CLN3), which maps to chromosome 16p, and by the "cherry-red-spot-myoclonus" syndrome of Guazzi or sialidosis type I, which has been localized to chromosome 10. A point mutation in the mitochondrial tRNA(Lys) coding gene can also cause PME in children and adults (MERFF).
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PMID:Progress in mapping human epilepsy genes. 829 22

Despite the original distinction between Alzheimer's disease (AD) and senile dementia, both are currently considered to be one single disease based on their common neuropathological findings. We have reviewed the literature to investigate whether there is proof to assume the existence of subgroups of AD. Historically, there is a division based on the age at onset. Although typical cortical symptoms may be more prominent in early onset cases they may be encountered in senile cases too. Cortical neuronal loss may be more severe in early onset patients, but hippocampal neuronal loss is equally severe in both groups. In older patients cerebral reserve is reduced by age-related neuronal loss and a small amount of AD-type lesions might be sufficient to cause dementia. Aphasia has been proposed as indicator of a subgroup. However, it probably occurs in all AD patients when the cortical degenerative process progresses. AD cases presenting with aphasia are rare and more often prove to be Pick's disease or primary progressive aphasia. Extrapyramidal signs are present in 25% of patients without neuroleptics and in 90% of all patients. They are usually of mild intensity, appear during the course of the disease and are found to be of extranigral origin. Myoclonus may also be encountered at any stage, although more frequent in early onset AD. Its presence is often associated with a more progressive course. Most AD cases are sporadic and some are familial, suggesting an autosomal dominant transmission. Molecular genetics reveals that some patients with familial early-onset AD have a mutation on chromosome 21. Other genes, probably on chromosome 19, may be associated with late onset familial cases, suggesting heterogeneity in familial AD. White matter involvement on computerized tomography or magnetic resonance imaging has been reported to be more prominent in a subgroup of AD patients, with later onset and confusional symptoms. The typical bilateral temporo-parietal hypometabolism on positron emission tomography and hypoperfusion on single photon emission computed tomography, is not found in all AD cases but may be indicative of a subgroup. Based on this review of the literature one homogeneous subgroup emerges: "probable" AD patients displaying memory disturbances with predominant cortical signs (especially aphasia), with a low prevalence of confusion and white matter involvement, exhibiting symptoms at a relatively early age but not exclusively below 65 years, and with a higher prevalence of genetic predisposition and more widespread neuropathological lesions at postmortem examination.
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PMID:[Heterogeneity of Alzheimer's disease]. 833 57

Alzheimer's disease (AD) is a heterogeneous entity presenting as sporadic and familial disease. In familial AD, there is evidence for genetic linkage to a yet undefined gene on chromosome 14 in early-onset pedigrees and on chromosome 19 in late-onset pedigrees. In a few early-onset kindreds, there were mutations in the amyloid precursor gene on chromosome 21. There is an increased frequency of apolipoprotein E (ApoE) epsilon4 allele in patients with late-onset AD. We studied the clinical presentation and profile of cognitive deficits in 58 AD patients at the early stage of the disease. We divided the AD patients into subgroups of sporadic late-onset (SLO) (> or = 65 years), familial late-onset (FLO) (> or = 65 years), sporadic early-onset (SEO) (<65 years), and familial early-onset (FEO) (<65 years) patients and into three subgroups according to their ApoE genotype zero epsilon4, one epsilon4, and two epsilon4 alleles. The AD subgroups did not differ in the global clinical severity of dementia or the duration of the disease. SLO, FLO, SEO, and FEO subgroups did not differ in clinical characteristics such as occurrence of rigidity, hypokinesia, tremor, myoclonus, hallucinations, delusions, or epileptic seizures nor in the profile of deficits on tests assessing memory, language, visuospatial, executive, and praxic functions. The epsilon4++ allele frequency was 0.43 for all AD patients and did not differ across subgroups divided according to the familial aggregation and age of onset. Patients with two epsilon4 alleles had earlier age at onset of dementia than those with no epsilon4 allele (63 +/- 9 versus 68 +/- 9 years), but otherwise the clinical symptoms and signs were not related to the ApoE genotype. However, the AD patients with two epsilon 4 alleles had lowest scores on memory tests and differed significantly from those with one or zero epsilon4 allele in the delayed list learning (p<0.05) and from those with zero epsilon4 allele in the immediate and delayed story recall. In contrast, verbal functions were better preserved in two epsilon4 patients than in those with other ApoE genotypes. This study failed to confirm the earlier reports of severe aphasia, agnosia, and apraxia in familial AD patients, but the clinical phenotype was similar irrespective to the familial aggregation. However, AD patients with two epsilon4 alleles are characterized by more severe memory loss and earlier age of onset than those without the epsilon4 allele.
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PMID:Clinical and neuropsychological characteristics in familial and sporadic Alzheimer's disease: relation to apolipoprotein E polymorphism. 861 4


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