Ala30Pro mutation in the gene encoding alpha-synuclein in Parkinson's disease.
Explore the source record for details and available documents.
Alanine↗
Biomedical subjects
J T Epplen
Publications and source records attributed to J T Epplen.
Evaluation of ROM1 as a candidate gene in generalised progressive retinal atrophy in dogs.
Generalised progressive retinal atrophy (gPRA) is a heterogeneous group of hereditary diseases causing degeneration of the retina in dogs and other animals. The genetic origin is unknown in most cases. We have screened the coding sequence of the ROM1 gene for disease causing mutations in Tibetan Terriers, Miniature Poodles, Dachshunds and Chesapeake Bay Retrievers by single strand conformation polymorphism analysis (SSCP). Two polymorphisms have been identified by sequencing, one in exon 1 in all examined breeds (position 210: G-->A; Gly40Arg and position 252: G-->T; Ala53-Ser). Another polymorphism was present in exon 2 (position 1150: C-->T and position 1195: C-->T) segregating in Miniature Poodles. None of these polymorphisms were cosegregating with gPRA rendering a disease causing mutation in the ROM1 gene unlikely.
Animals↗
Isolation and characterization of microsatellite markers in the nuclear genome of the brown alga Laminaria digitata (Phaeophyceae).
Explore the source record for details and available documents.
Base Sequence↗
Replication analysis of a putative susceptibility locus (EGI) for idiopathic generalized epilepsy on chromosome 8q24.
PURPOSE: The present replication study was designed to test the validity of a previously mapped susceptibility locus (EGI) for common subtypes of idiopathic generalized epilepsy (IGE) in chromosomal region 8q24. METHODS: Thirty-eight multiplex families of probands with common IGE syndromes were included in the present study. Parametric and nonparametric multipoint linkage analyses were conducted between the IGE trait (either "idiopathic" generalized seizure or generalized spike-wave EEG discharges) and three microsatellite polymorphisms (D8S256, D8S284, D8S1128) encompassing the putative EGI locus. RESULTS: Parametric and nonparametric multipoint linkage analysis provided no evidence for linkage between the IGE trait and the markers encompassing the putative EGI locus. Moreover, we noted no indication favoring linkage to this chromosomal region in two distinct subsets of families subdivided by the absence (n = 18) or presence (n = 20) of family members with juvenile myoclonic epilepsy (JME). CONCLUSIONS: We failed to replicate evidence of a major locus (EGI) for common familial IGE in chromosome region 8q24. On the contrary, our present parametric linkage results provide evidence against linkage across the region under a broad range of genetic models. If there is a susceptibility locus for IGE in this region, the effect size or the proportion of linked families is too small to detect linkage in these families. Taking into account the problems in replicating initial linkage claims in oligogenic traits, further linkage studies in additional family sets are necessary to evaluate the validity of the previous linkage finding.
Chromosome Mapping↗
An isoform of ataxin-3 accumulates in the nucleus of neuronal cells in affected brain regions of SCA3 patients.
Autosomal dominant spinocerebellar ataxias (SCA) form a group of clinically and genetically heterogeneous neurodegenerative disorders. The defect responsible for SCA3/Machado-Joseph disease (MJD) has been identified as an unstable and expanded (CAG)n trinucleotide repeat in the coding region of a novel gene of unknown function. The MJD1 gene product, ataxin-3, exists in several isoforms. We generated polyclonal antisera against an alternate carboxy terminus of ataxin-3. This isoform, ataxin-3c, is expressed as a protein of approximately 42 kDa in normal individuals but is significantly enlarged in affected patients confirming that the CAG repeat is part of the ataxin-3c isoform and is translated into a polyglutamine stretch, a feature common to all known CAG repeat disorders. Ataxin-3 like immunoreactivity was observed in all human brain regions and peripheral organs studied. In neuronal cells of control individuals, ataxin-3c was expressed cytoplasmatically and had a somatodendritic and axonal distribution. In SCA3 patients, however, C-terminal ataxin-3c antibodies as well as anti-ataxin-3 monoclonal antibodies (1 H9) and anti-ubiquitin antibodies detected intranuclear inclusions (NIs) in neuronal cells of affected brain regions. A monoclonal antibody, 2B6, directed against an internal part of the protein, barely detected these NIs implying proteolytic cleavage of ataxin-3 prior to its transport into the nucleus. These findings provide evidence that the alternate isoform of ataxin-3 is involved in the pathogenesis of SCA3/MJD. Intranuclear protein aggregates appear as a common feature of neurodegenerative polyglutamine disorders.
Amino Acid Sequence↗
Spinocerebellar ataxia type 6: genotype and phenotype in German kindreds.
OBJECTIVE: Spinocerebellar ataxia type 6 (SCA6) is an autosomal dominant cerebellar ataxia (ADCA) of which the mutation causing the disease has recently been characterised as an expanded CAG trinucleotide repeat in the gene coding for the alpha1A-subunit of the voltage dependent calcium channel. The aim was to further characterise the SCA6 phenotype METHODS: The SCA6 mutation was investigated in 69 German families with ADCA and 61 patients with idiopathic sporadic cerebellar ataxia and the CAG repeat length of the expanded allele was correlated with the disease phenotype. RESULTS: Expanded alleles were found in nine of 69 families as well as in four patients with sporadic disease. Disease onset ranged from 30 to 71 years of age and was significantly later than in other forms of ADCA. Age at onset correlated inversely with repeat length. The SCA6 phenotype comprises predominantly cerebellar signs in concordance with isolated cerebellar atrophy on MRI. Non-cerebellar systems were only mildly affected with external ophthalmoplegia, spasticity, peripheral neuropathy, and parkinsonism. Neither these clinical signs nor progression rate correlated with CAG repeat length. CONCLUSIONS: This study provides the first detailed characterisation of the SCA6 phenotype. Clinical features apart from cerebellar signs were highly variable in patients with SCA6. By comparison with SCA1, SCA2, and SCA3 no clinical or electrophysiological finding was specific for SCA6. Therefore, the molecular defect cannot be predicted from clinical investigations. In Germany, SCA6 accounts for about 13% of families with ADCA. However, up to 30% of SCA6 kindreds may be misdiagnosed clinically as sporadic disease due to late manifestation in apparently healthy parents. Genetic testing is therefore recommended for the SCA6 mutation also in patients with putative sporadic ataxia.
Adult↗
On GATAGATA and other "junk" in the barren stretch of genomic desert.
(GATA)n and additional simple repeated DNA sequences have long been known but functional analyses along traditional research strategies have not yielded definitive results. Therefore these elements are commonly regarded as genomic "junk" although they represent assets for innovative methodological approaches and especially for speculations. While extensively using microsatellites for genome mapping and genetic relationship analyses, it was also realized that certain simple repeats can cause human trinucleotide block expansion diseases. Hence these simple repeat elements comprise an exceptional range of biological meaning, i.e. from genetically absolutely neutral markers for genome analysis, behavioral and population genetic studies to dominant and invariably disease causing mutations with complete penetrance. The quest into why there is so much repetitive junk in recent genomes can be answered only in part and sequentially, but sometimes--even after substantial efforts--not for the given element.
Animals↗
Dispensable and indispensable genes in an ameiotic fish, the Amazon molly Poecilia formosa.
All-female vertebrates are excellent model systems for studying many evolutionary problems. One of these is the Amazon molly. In this review, three aspects of its biology are discussed: (1) An important question is how dispensable genes, such as all male coding genes, evolve in this species. A number of studies found that most of these genes remain remarkably stable and functional. (2) The gynogenetic Amazon mollies have to live in sympatry with males of a gonochoristic species, because sperm are needed to trigger embryogenesis. Yet, Amazon mollies cannot replace their sexual competitors, because this would lead to their own extinction. Studies on the behavior of Amazon mollies and their sperm-donor species indicate that a number of behavior patterns stabilize the mating system by providing Amazon mollies with the copulations they need to reproduce. (3) The age of Amazon mollies has been estimated to be approximately 100,000 years. This is older than predicted by some theoretical models. In Amazon mollies two ways to occasionally incorporate fresh genetic material have evolved. One way is to add one complete set of paternal chromosomes, which, in nature, leads to stable triploid lineages. The second way is the incorporation of minute, centromere-containing microchromosomes. The evolutionary impact of these phenomena, however, is not resolved so far and needs further study.
Animals↗
[Telomere lengths and telomerase activity in liposarcomas].
We measured telomerase activity in 36 malignant and seven benign lipomatous neoplasias from 34 patients to assess the role of telomerase in the development of liposarcoma. The sensitive PCR-based telomerase assay (telomeric repeat amplification protocol-TRAP) was applied. We correlated telomerase activity with the shortening or elongation of telomeric repeat fragment length (TRF), measured by using hybridization with a telomere specific oligonucleotide probe. Telomerase activity was demonstrated in 69% of malignant tumors. This information may be helpful in distinguishing benign tumors from malignant neoplasias. Telomerase expression, however, seems to be characteristic of poorly differentiated liposarcomas. Telomerase activity was not correlated with age at the time of diagnosis or with sex. We observed that telomerase expressing tumors had higher proliferation indices than neoplasias lacking telomerase. Telomerase activity was observed in all eight recurrences, suggesting a close association of telomerase with the biologic behavior of liposarcomas. Therefore, we assume that telomerase plays a key role in the establishment and progression of lipomatous tumors.
Humans↗
Genetic distinction of scorpionflies (Panorpa vulgaris) by microsatellites.
Explore the source record for details and available documents.
Alleles↗
Spinocerebellar ataxia type 2. Genotype and phenotype in German kindreds.
BACKGROUND: Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominant cerebellar ataxia (ADCA) for which the disease-causing mutation has recently been characterized as an expanded CAG trinucleotide repeat. We investigated 64 families of German ancestry with ADCA and 55 patients with sporadic ataxia for the SCA2 mutation. RESULTS: Expanded alleles were found in 6 of the 64 families and in 1 patient with sporadic ataxia. This patient had a de novo mutation from an intermediate paternal allele. Length of repeats in 21 patients with SCA2 ranged from 36 to 52 CAG motifs and was inversely correlated with age at onset and progression of the disease. Expanded alleles were unstable during meiosis; paternal transmission especially caused significant anticipation of onset up to 26 years earlier. The SCA2 phenotype differed from those of SCA1 and SCA3 with higher frequencies of slowed ocular movements, postural and action tremor, myoclonus, and hyporeflexia. However, no single feature was sufficient to permit a specific clinical diagnosis. CONCLUSIONS: Spinocerebellar ataxia type 2 accounts for about 10% of German families with ADCA but may also be present in sporadic ataxia due to de novo mutations. Clinical features are highly variable among and even within families. However, the size of the expanded repeat influences the phenotype and is relevant for course and prognosis of the disease.
Adolescent↗
Genetic predisposition to multiple sclerosis as revealed by immunoprinting.
This study was designed to examine the immunogenetic background predisposing to multiple sclerosis (MS). Three hundred fifty-eight clinically well-characterized MS patients from Germany were investigated and compared to 395 healthy control subjects. Each individual was genotyped for 22 polymorphic markers located within or close to immunorelevant candidate genes including HLA-DRB1*, T-cell receptor (TCR), cell interaction molecules, cytokines, and cytokine receptor genes. Altogether, approximately 17,000 genetic analyses were performed. Patients were grouped according to the course of MS-relapsing-remitting or chronic progressive. Most of the genetic markers were not associated with increased risk or their exact contribution was not clear (e.g., tumor necrosis factor). The relative risks for HLA-DRB1*15+ and DRB1*03+ individuals were 3.64 and 1.42, respectively. In both groups of patients, certain TCRB gene polymorphisms were risk factors. In DRB1*03+ individuals the relative risk was increased (> 22) when a specific TCRBV6S3 allele was also inherited. Furthermore, distinct linkage disequilibria of TCRBV6S1/TCRBV6S3 elements in patients and control subjects strongly suggested an additional risk factor in the TCRBV region for DRB1*15+ individuals. These findings are discussed with respect to the pathogenesis and rational approaches to the therapy of MS.
Adolescent↗
Autosomal dominant cerebellar ataxia: phenotypic differences in genetically defined subtypes?
Seventy-seven families with autosomal dominant cerebellar ataxia were analyzed for the CAG repeat expansions causing spinocerebellar ataxia (SCA) types 1, 2, 3, and 6. The SCA1 mutation accounted for 9%, SCA2 for 10%, SCA3 for 42%, and SCA6 for 22% of German ataxia families. Seven of 27 SCA6 patients had no family history of ataxia. Age at onset correlated inversely with repeat length in all subtypes. Yet the average effect of one CAG unit on onset age was different for each SCA subtype. We compared clinical, electrophysiological, and magnetic resonance imaging (MRI) findings to identify phenotypic characteristics of genetically defined SCA subtypes. Slow saccades, hyporeflexia, myoclonus, and action tremor proposed SCA2. SCA3 patients frequently developed diplopia, severe spasticity or pronounced peripheral neuropathy, and impaired temperature discrimination, apart from ataxia. SCA6 presented with a predominantly cerebellar syndrome and patients often had onset after 55 years of age. SCA1 was characterized by markedly prolonged peripheral and central motor conduction times in motor evoked potentials. MRI scans showed pontine and cerebellar atrophy in SCA1 and SCA2. In SCA3, enlargement of the fourth ventricle was the main sequel of atrophy. SCA6 presented with pure cerebellar atrophy on MRI. However, overlap between the four SCA subtypes was broad.
Adolescent↗
On simple repetitive DNA sequences and complex diseases.
Simple repetitive DNA sequences are abundantly interspersed in eukaryote genomes and therefore useful in genome research and genetic fingerprinting in plants, fungi and animals, including man. Recently, simple repeats were also identified in some prokaryotic genomes. Hence the same probes can be applied for multilocus DNA fingerprinting in medically relevant bacteria. Simple repeats including composite dinucleotide microsatellites are differentially represented in different compartments of eukaryote genomes. Expanded triplet blocks in and around certain genes may, for example, cause so-called trinucleotide diseases in man. As a consequence, simple repetitive sequences should also be characterized with respect to their influences on the DNA structure, gene expression, genomic (in)stability and their development on an evolutionary time scale. Here three examples of microsatellites in the human major histocompatibility complex (HLA) are investigated, a (GT)n microsatellite situated 2 kb 5' off the lymphotoxin alpha (LTA) gene, a (GAA)n block in the 5' part of the HLA-F gene and a composite (GT)n(GA)m stretch in the second intron of HLA-DRBl genes. Grossly differing mutation rates are evident in these elements as well as varying linkage disequilibria. The unfolding of these simple repeats in distant human populations is covered including Caucasians, Bushmen and South American Indians. Furthermore, implications of simple repeat neighboring genes are discussed for the multifactorial diseases multiple sclerosis (MS), rheumatoid arthritis (RA) and early onset pauciarticular arthritis (EOPA). Polymorphisms of HLA-DRBl and T cell receptor beta variable (TCRBV) genes confer susceptibility for these autoimmune diseases as demonstrable by intronic simple repeat variability. Microsatellite polymorphisms within the TNF region reveal linkage disequilibria with HLA-DRBl and different promotor alleles of the TNFA gene. Disease associations with TNFA microsatellite alleles are, on the one hand, secondary to associations with HLA-DRBl genes (in MS) or they represent additional risk factors (in RA, EOPA) on the other hand. Evolutionary persistence, various structural conformations and the specific binding of nuclear proteins to several simple repeat sequences refute the preconceptions of biological insignificance for all of these ubiquitously interspersed elements.
Arthritis↗
Transmission distortion of the mutant alleles in spinocerebellar ataxia.
Spinocerebellar ataxia type 1 and type 3 (SCA1, SCA3) are autosomal dominant neurodegenerative disorders caused by expanded CAG trinucleotide repeats in novel genes. In our collective of SCA1 and SCA3 families, we observed distortion of the Mendelian 1:1 segregation of the disease. The mutated alleles were preferentially transmitted by female carriers in SCA3, whereas a gender effect on clinical features such as age of onset was not obvious. The mechanism underlying segregation distortion remains to be established.
Age of Onset↗
Coding versus intron variability: extremely polymorphic HLA-DRB1 exons are flanked by specific composite microsatellites, even in distant populations.
Although microsatellite typing is the dominant method in genome research and indirect gene diagnosis, precise relationships of exonic and adjacent simple repeat polymorphisms are not known. We investigated exon 2 sequences of HLA-DRB1 genes and their neighbouring (GT)n(GA)m repeats including the intervening single copy spacer. DRB1 is the most polymorphic protein-coding locus in man and all vertebrates investigated. The entire DRB1 variability exists in exon 2. DRB1 genes in different haplotype groups (DR1, DR51, DR52, DR8 and DR53) are accompanied by characteristic modifications of the (GT)n(GA)m block (3' to group-specific single copy spacers). Among more than 520 alleles analysed, > 100 different types of microsatellites were observed. The perfect (GT)n and (GA)m blocks vary in length and may be partly 'degenerated', mostly in a subgroup-specific manner. Interestingly, the extent of microsatellite diversity varies in given DRB1 alleles. While the microsatellites of the DR7, DR9 alleles and in the DR1 group are virtually invariant, in DR4 and DR13, in particular, simple repeats appear hypervariable with at least 15 or 17 different length alleles, respectively. Comparing Caucasians, Bushmen and South American Indians, the microsatellite variation in identical DRB1 alleles (e.g. DRB1*0102, 03011, 1302) is smaller than within any of the DR groups in Caucasians. Taken together, extremely polymorphic DRB1 exons evolve in concert with certain variants of an exceptionally well-preserved microsatellite.
Cloning, Molecular↗
Polymorphisms in the PMP-22 gene region (17p11.2-12) are crucial for simplified diagnosis of duplications/deletions.
DNA duplications and deletions of a 1.5-Mb region in chromosome 17p11.2-12 comprising the gene encoding peripheral myelin protein 22 (PMP-22) are the common mutations in Charcot-Marie-Tooth disease type 1 (CMT1) and hereditary neuropathy with liability to pressure palsies (HNPP). A 1.7-kb recombination hotspot region has been identified within misaligned flanking repeats (CMT1-REP elements) by detection of CMT- and HNPP-specific junction fragments in Southern blot analyses. In order to simplify routine diagnosis we introduce a polymerase chain reaction-based method to identify directly specific REP junction fragments. Using this test, specific fragments were detected in approximately 67% of both CMT duplication and HNPP deletion cases. Polymorphism within a specific restriction enzyme recognition site is crucial for both Southern blot and PCR analyses of junction fragments.
Blotting, Southern↗
Differential stability of the (GAA)n tract in the Friedreich ataxia (STM7) gene.
Friedreich ataxia (FA) is an autosomal recessive, neurodegenerative disorder characterized by polypurine trinucleotide expansion. The (GAA)n motif is located in intron 18 of the STM7 gene (previously considered as intron 1 of the X25 gene) on chromosome 9q13. We studied the distribution profile of the polymorphic (GAA)n repetitive tract in 178 healthy individuals. The number of repeats of the trinucleotide block ranged from 7 to 29. In three individuals there were more than 29 repetitions of the GAA motif. While two of the individuals would be diagnosed as carriers of the FA mutation (GAA size > 90), the status of the third person, with a (GAA)58 tract, appears less clear at present. Thus an FA carrier rate of 1/60 to 1/90 can be assumed for the German population. In addition an intermediate-sized allele, (GAA)38 was identified in a mother with two affected children. The (GAA)38 allele appears to be expanded during transmission to at least (GAA)66 and (GAA) > 400 in her two FA-affected offspring. Therefore the shortest known STM7 allele conferring FA is (GAA)66. These novel facts have to be considered for differential diagnosis and definition of the FA carrier state.
Adult↗