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A Brice

Publications and source records attributed to A Brice.

At least 55 records · Page 3Linked to original sources
PubMed2002

CAG/CTG repeat expansions at the Huntington's disease-like 2 locus are rare in Huntington's disease patients.

The authors report a large series of patients with Huntington disease (HD)-like phenotype without CAG repeat expansions in the IT15 gene that were screened for the newly identified CAG/CTG expansion in the gene encoding junctophilin-3. Normal alleles in controls had from 8 to 28 repeats. A single patient of North African origin with typical HD carried an allele with 50 uninterrupted repeats, representing approximately 2% of the non-IT15 HD patients tested. Therefore, further genetic heterogeneity is expected in HD.

Adolescent↗
PubMed2002

Combined vitamin B6-magnesium treatment in autism spectrum disorder.

BACKGROUND: The use of mega-vitamin intervention began in the early 1950's with the treatment of schizophrenic patients. Pyroxidine (vitamin B6) was first used with children diagnosed with "autism syndrome" when speech and language improvement was observed in some children as a result of large doses of B6. A number of published studies attempted to assess the effects of vitamin B6-Mg (Mg was found to reduce undesirable side effects from B6) on a variety of characteristics such as verbal communication, non-verbal communication, interpersonal skills, and physiological function, in individuals with autism. OBJECTIVES: To determine the efficacy of vitamin B6 and magnesium (B6-Mg) for treating social, communication and behavioural responses of children and adults with autism. SEARCH STRATEGY: We searched the Cochrane Controlled Trials Register (Cochrane Library, Issue 2, 2002), MEDLINE (1966- January 2002), EMBASE (1980-January 2002), PsychINFO (1887 - January 2002), Dissertation Abstracts International (1861 - January 2002). The search engine FirstSearch was also used (January 2002). Reference lists for all the obtained studies and other review articles were examined for additional studies. SELECTION CRITERIA: All studies in which the participants were randomly allocated prior to intervention and in which outcomes were compared to either a placebo or non-treated group were included. DATA COLLECTION AND ANALYSIS: Two reviewers independently evaluated all potential studies identified as indicated above for inclusion. MAIN RESULTS: Two trials were included in the review. Both studies used a double-blind crossover design. One study (Tolbert 1993) provided insufficient data to conduct an analysis. The senior author was contacted for supporting data but was unable to provide the needed information. The remaining study (Findling, 1997) yielded no significant differences between treatment and placebo group performances following the B6 intervention on measures of social interaction, communication, compulsivity, impulsivity, or hyperactivity. REVIEWER'S CONCLUSIONS: Due to the small number of studies, the methodological quality of studies, and small sample sizes, no recommendation can be advanced regarding the use of B6-Mg as a treatment for autism.

Adult↗
PubMed2002

PARK6 is a common cause of familial parkinsonism.

The Parkin gene is responsible for about 50% of autosomal recessive juvenile parkinsonism (ARJP) and less than 20% of sporadic early onset cases. We recently mapped a novel ARJP locus (PARK6) on chromosome 1p. Linkage to PARK6 was confirmed in 8 families from 4 different European countries. These families share some clinical features with the European Parkin-positive cases, with a wide range of ages at onset and slow progression. However, features typical of ARJP, such as dystonia and sleep benefit, were not observed, making the clinical presentation of late-onset cases indistinguishable from that of idiopathic PD. The determination of the smallest region of homozygosity in one consanguineous family allowed reducing the candidate interval to 9 cM. PARK6 appears to be an important locus for ARJP in Europe.

Chromosomes, Human, Pair 1↗
PubMed2002

[Molecular genetic analysis of essential tremor].

Essential tremor (ET) is the most common extrapyramidal disorder of the central nervous system with autosomal dominant transmission in the majority of cases and age-dependent penetrance of the mutant gene. In a number of cases, it shares some phenotypic features with autosomal dominant idiopathic torsion dystonia (locus DYT1 on chromosome 9q32-34) and is genetically heterogeneous: distinct variants of ET were mapped to chromosomes 3q13 (ETM1) and 2p22-25 (ETM2). We performed studies of candidate loci in a group of Slavonic (11 patients) and Tajik (19 patients) families with ET. Mutational analysis of the DYT gene in probands did not reveal the major deletion 946-948delGAG characteristic of idiopathic torsion dystonia, which allows one to genetically distinguish the studied hereditary forms of ET and torsion dystonia. Based on analysis of genetic linkage in informative Tajik pedigrees with ET, linkage to locus ETM1 on chromosome 3q13 was established in four families. Maximum pairwise Lod score was 2.46 at recombination fraction of theta = 0.00; maximum combined multipoint Lod score was 3.35 for marker D3S3720 and a common "mutant" haplotype for markers D3S3620, D3S3576, and D3S3720 allowed us to locate a mutant gene in a relatively narrow chromosome region spanning 2 cM. In one informative pedigree with ET, both candidate loci ETM1 and ETM2 were definitely excluded on the basis of negative Lod scores obtained by linkage estimations, which testifies to the existence of another distinct gene for autosomal dominant ET.

Carrier Proteins↗
PubMed2001

Similarities between spinocerebellar ataxia type 7 (SCA7) cell models and human brain: proteins recruited in inclusions and activation of caspase-3.

Spinocerebellar ataxia type 7 (SCA7) is an autosomal dominant polyglutamine disorder presenting with progressive cerebellar ataxia and blindness. The molecular mechanisms underlying the selective neuronal death typical of SCA7 are unknown. We have established SCA7 cell culture models in HEK293 and SH-SY5Y cells, in order to analyse the effects of overexpression of the mutant ataxin-7 protein. The cells readily formed anti-ataxin-7 positive, fibrillar inclusions and small, nuclear electron dense structures. We have compared the inclusions in cells expressing mutant ataxin-7 and in human SCA7 brain tissue. There were consistent signs of ongoing abnormal protein folding, including the recruitment of heat-shock proteins and proteasome subunits. Occasionally, sequestered transcription factors were found. Activated caspase-3 was recruited into the inclusions in both the cell models and human SCA7 brain and its expression was upregulated in cortical neurones, suggesting that it may play a role in the disease process. Finally, on the ultrastructural level, there were signs of autophagy and nuclear indentations, indicative of a major stress response in cells expressing mutant ataxin-7.

Adult↗
PubMed2001

Pseudo-dominant inheritance and exon 2 triplication in a family with parkin gene mutations.

The authors report an Italian family with pseudo-dominant inheritance of parkinsonism attributable to parkin gene mutations. The father (disease onset at age 57 years) was homozygous for a triplication of exon 2 that is so far unique. The unaffected mother was heterozygous for deletions of exons 3 and 4, and the son (onset at age 31 years) was a compound heterozygote carrying both mutations. Thus, pseudo-dominant inheritance of parkin gene mutations has to be considered in early-onset parkinsonism, and sensitive screening techniques, such as semiquantitative multiplex PCR, should be applied.

Adult↗
PubMed2001

Ataxin-7 interacts with a Cbl-associated protein that it recruits into neuronal intranuclear inclusions.

Spinocerebellar ataxia 7 (SCA7) is a neurodegenerative disease caused by expansion of a CAG repeat in the coding region of the SCA7 gene. The disease primarily affects the cerebellum and the retina, but also many other central nervous system (CNS) structures as the disease progresses. Ataxin-7, encoded by the SCA7 gene, is a protein of unknown function expressed in many tissues including the CNS. In normal brain, ataxin-7 is found in the cytoplasm and/or nucleus of neurons, but in SCA7 brain ataxin-7 accumulates in intranuclear inclusions. Ataxin-7 is expressed ubiquitously, but mutation leads to neuronal death in only certain areas of the brain. This selective pattern of degeneration might be explained by interaction with a partner that is specifically expressed in vulnerable cells. We used a two-hybrid approach to screen a human retina cDNA library for ataxin-7-binding proteins, and isolated R85, a splice variant of Cbl-associated protein (CAP). R85 and CAP are generated by alternative splicing of the gene SH3P12 which we localized on chromosome 10q23-q24. The interaction between ataxin-7 and the SH3P12 gene products (SH3P12GPs) was confirmed by pull-down and co-immunoprecipitation. SH3P12GPs are expressed in Purkinje cells in the cerebellum. Ataxin-7 colocalizes with full-length R85 (R85FL) in co-transfected Cos-7 cells and with one of the SH3P12GPs in neuronal intranuclear inclusions in brain from a SCA7 patient. We propose that this interaction is part of a physiological pathway related to the function or turnover of ataxin-7. Its role in the pathophysiological process of SCA7 disease is discussed.

Alternative Splicing↗
PubMed2001

A major locus for several phenotypes of myoclonus--dystonia on chromosome 7q.

Myoclonus--dystonia is a genetically heterogeneous autosomal dominant disorder caused by a mutation in the D2 dopamine receptor on chromosome 11 and a locus on chromosome 7q21-q31. The authors tested linkage to the chromosome 7q candidate region in four families with either myoclonic dystonia (n = 3) or essential myoclonus (n = 1). Age at onset ranged from 0.5 to 38 years. Only four patients from two families had a positive response to alcohol. Lod scores were positive in all four families, suggesting that chromosome 7q21-q31 is a major locus for myoclonus-dystonia with several phenotypes.

Adult↗
PubMed2001

Parkin immunoreactivity in the brain of human and non-human primates: an immunohistochemical analysis in normal conditions and in Parkinsonian syndromes.

The etiology of Parkinson's disease is unknown, but the gene involved in an autosomic recessive form of the disease with early onset has recently been identified. It codes for a protein with an unknown function called parkin. In the present study we produced a specific polyclonal antiserum against human parkin. Immunohistochemical analysis showed that parkin is expressed in neuronal perikarya and processes but also in glial and blood vessels in the primate brain (human and monkey). Electron microscopy indicated that parkin immunoreactivity is mostly located in large cytoplasmic vesicles and at the level of the endoplasmic reticulum. Parkin was expressed heterogeneously in various structures of the brain. It was detectable in the dopaminergic systems at the level of the perikarya in the mesencephalon but also in the striatum. However, parkin was also expressed by numerous nondopaminergic neurons. The staining intensity of parkin was particularly high in the hippocampal formation, the pallidal complex, the red nucleus, and the cerebellum. Comparison of control subjects with patients with Parkinson's disease and control animals with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-intoxicated animals revealed a loss of parkin-immunoreactive neurons only in the substantia nigra pars compacta. Furthermore, the surviving dopaminergic neurons in the parkinsonian state continued to express parkin at a level similar to that observed in the control situation. These data indicate that parkin is a widely expressed protein. Thus, the degeneration of dopaminergic neurons in familial cases of Parkinson's disease with autosomal recessive transmission cannot be explained solely in terms of an alteration of this protein.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed2001

Clinical and pathologic abnormalities in a family with parkinsonism and parkin gene mutations.

A Dutch family with autosomal recessive early-onset parkinsonism showed a heterozygous missense mutation in combination with a heterozygous exon deletion in the parkin gene. Although the main clinical syndrome consisted of parkinsonism, the proband clinically had additional mild gait ataxia and pathologically showed neuronal loss in parts of the spinocerebellar system, in addition to selective loss of dopaminergic neurons in the substantia nigra pars compacta. Lewy bodies and neurofibrillary tangles were absent, but tau pathology was found.

Aged↗
PubMed2001

A mutation in periaxin is responsible for CMT4F, an autosomal recessive form of Charcot-Marie-Tooth disease.

Charcot-Marie-Tooth (CMT) disease is a heterogeneous group of inherited peripheral motor and sensory neuropathies characterized by chronic distal weakness with progressive muscular atrophy and sensory loss in the distal extremities. Inheritance can be autosomal dominant, X-linked or autosomal recessive (ARCMT). Recently, a locus responsible for a demyelinating form of ARCMT disease, named CMT4F, has been mapped on 19q13 in a large consanguineous Lebanese family. L- and S-periaxin are proteins of myelinating Schwann cells and homozygous periaxin-null mice display extensive demyelination of myelinated fibers in the peripheral nervous system, which suggests that the periaxin gene is a good candidate gene for an ARCMT disease. The human gene encoding the periaxins (PRX) was mapped to 19q13, in the CMT4F candidate interval. After characterizing the human PRX gene, we identified a nonsense R196X mutation in the Lebanese family which cosegregated with CMT. Histopathological and immunohistochemical analysis of a sural nerve biopsy of one patient revealed common features with the mouse mutant and the absence of L-periaxin from the myelin sheath. These data confirm the importance of the periaxin proteins to normal Schwann cell function and substantiate the utility of the periaxin-null mouse as a model of ARCMT disease.

Amino Acid Sequence↗
PubMed2001

Origin of the mutations in the parkin gene in Europe: exon rearrangements are independent recurrent events, whereas point mutations may result from Founder effects.

A wide variety of mutations in the parkin gene, including exon deletions and duplications, as well as point mutations, result in autosomal recessive early-onset parkinsonism. Interestingly, several of these anomalies were found repeatedly in unrelated patients and may therefore result from recurrent, de novo mutational events or from founder effects. In the present study, haplotype analysis, using 10 microsatellite markers covering a 4.7-cM region known to contain the parkin gene, was performed in 48 families, mostly from European countries, with early-onset autosomal recessive parkinsonism. The patients carried 14 distinct mutations in the parkin gene, and each mutation was detected in more than one family. Our results support the hypothesis that exon rearrangements occurred independently, whereas some point mutations, found in families from different geographic origins, may have been transmitted by a common founder.

Age of Onset↗
PubMed2001

Evidence for digenic inheritance in a family with both febrile convulsions and temporal lobe epilepsy implicating chromosomes 18qter and 1q25-q31.

We report a clinical and genetic study of a French family among whom febrile convulsions (FC) are associated with subsequent temporal lobe epilepsy (TLE) in the same individual, without magnetic resonance imaging-identifiable hippocampal abnormalities. Linkage analyses excluded the loci FEB1 and FEB2, previously implicated in FC; the GEFS+1 locus responsible for generalized epilepsy with febrile seizures plus; and the locus implicated in lateral temporal lobe epilepsy. After scanning the entire genome, significant lod scores (>3) for markers on 18qter and suggestive lod scores (>2) for markers on 1q25-q31 were obtained. An analysis of the haplotypes at these two loci supported the hypothesis that two genes segregated with the phenotype. All patients shared common haplotypes for both 1q25-q31 and 18qter chromosomes. All but one unaffected at-risk individuals carried only one, or none, of the disease haplotypes. Under the assumption of digenic inheritance, haplotype reconstruction defined a 26 cM interval on chromosome 1 and a 10 cM interval on chromosome 18. This family suggests that the association between FC and TLE may be observed in the absence of hippocampal structural abnormalities and that they may have, in some cases, a common genetic basis.

Adolescent↗
PubMed2001

The parkin gene and its phenotype. Italian PD Genetics Study Group, French PD Genetics Study Group and the European Consortium on Genetic Susceptibility in Parkinson's Disease.

Mutations of the parkin gene on chromosome 6 cause autosomal recessive, early onset parkinsonism. This is the most frequent form of monogenic parkinsonism so far identified. The associated phenotypical spectrum encompasses early onset, levodopa-responsive parkinsonism (average onset in the early 30s in Europe), and it overlaps with dopa-responsive dystonia in cases with the earliest onset, and with clinically typical Parkinson's disease in cases with later onset. Despite clinical features, Lewy bodies are not found at autopsy in brains of patients with parkin mutations. The parkin protein possesses ubiquitin ligase activity, which is abolished by the pathogenic mutations.

Age of Onset↗