Identification of the human ubiquitin specific protease 31 (USP31) gene: structure, sequence and expression analysis.

Parkinson's disease (PD) is a common neurodegenerative disorder with clinical features of bradykinesia, rigidity and resting tremor resulting from the deficiency of dopamine in the nigrostriatal system. Recently, PARK6 was identified as a novel locus associated with autosomal recessive PD. Here we report the identification and characterization of a novel human deubiquitylating gene (USP31), which maps to the critical PARK6 region. Database analysis and 5' RACE identified a 4070bp cDNA, encoded by 27 exons spanning approximately 105kbp of genomic sequence. The predicted protein of 1035 amino acids included a conserved ubiquitin hydrolase region (Prosite profile PS50235), a DUSP (domain in ubiquitin specific proteases-Smart00695) and a ubiquitin-like domain (Prosite pattern PS00299). Northern blot analysis revealed a single USP31 transcript of approximately 4 kb, which was primarily expressed in the testis and lung.

SCA2 may present as levodopa-responsive parkinsonism.

Some kindreds with familial parkinsonism exhibit genetic anticipation, suggesting possible involvement of trinucleotide repeat expansion. Recent reports have shown trinucleotide repeat expansions in the spinocerebellar ataxia 2 (SCA2) gene in patients with levodopa-responsive parkinsonism. We tested 136 unrelated patients with familial parkinsonism for SCA2 mutations. Two probands had borderline mutations; the rest were normal. (or=36 is pathogenic). The expanded allele segregated with neurological signs in one kindred. The absence of borderline mutations in the normal population, and the co-segregation of the expanded allele with neurological signs in one kindred suggest that SCA2 mutations may be responsible for a subset of familial parkinsonism.

Two large Polish kindreds with levodopa-responsive Parkinsonism not linked to known Parkinsonian genes and loci.

PURPOSE: We describe two newly discovered large Polish families with Parkinsonism, PL-Krakow 1 and PL-Krakow 2. SCOPE: As illustrated by case reports from two patients, the disease phenotype is similar to that seen in patients with idiopathic Parkinson's disease, and affected individuals show a positive response to levodopa therapy. Molecular genetic studies failed to demonstrate a single chromosomal haplotype that segregated with disease for any of the known loci for Parkinsonism. CONCLUSIONS: The study of large kindreds such as this provides opportunities to find new Parkinsonian loci and mutations. This knowledge will help to better our understanding of the basic mechanisms leading to the degeneration of vulnerable substantia nigra neurons and other susceptible brain structures.

Accurate determination of ataxin-2 polyglutamine expansion in patients with intermediate-range repeats.

Spinocerebellar ataxia, type 2 (SCA2), results from an expansion of a stretch of polyglutamine repeats within the coding sequence of the ataxin-2 gene (ATX2), localized to chromosome 12q23-24. Recent studies have widened the clinical phenotype, notably for individuals with repeats of intermediate size, from 32 to 35 glutamine residues. This narrow range necessitates precise determination of repeat size. Diagnostic laboratories most often perform direct genotyping of ATX2 from polymerase chain-amplified patient DNA with subsequent sizing utilizing slab gel polyacrylamide gel electrophoresis (PAGE) or capillary electrophoresis. Using cloning and sequencing methods, we have constructed a ladder of ATX2 alleles of known size and sequence composition. This freely available size ladder will facilitate future quantification of expansions of the ATX2 locus.

Ethnic differences in the expression of neurodegenerative disease: Machado-Joseph disease in Africans and Caucasians.

We describe several families of African origin with SCA3/Machado-Joseph disease gene expansions. In these cases, the phenotype ranges from ataxia with parkinsonian signs to a syndrome clinically almost indistinguishable from idiopathic, L-dopa-responsive Parkinson's disease. In contrast, these parkinsonian phenotypes are rare in those of European descent. Haplotype analysis shows that these African families do not share a common founder, thus a cis-acting element in the promoter is unlikely to be responsible these unusual presentations. We suggest that trans-acting factors are responsible for the variable phenotype and discuss the implications of diseases showing racially different expressivities.

Clinical, 18F-dopa PET, and genetic analysis of an ethnic Chinese kindred with early-onset parkinsonism and parkin gene mutations.

We report on clinical (18)F-labeled 6-fluorodopa ((18)F-dopa) positron emission tomography (PET) and molecular genetic analyses of an ethnic Chinese family in which three siblings presented with early-onset Parkinson's disease. As described in some parkin patients, neither sleep benefit nor diurnal fluctuation was noted. Interestingly, depression, anxiety, and obsessive-compulsive disorders were manifest. The (18)F-dopa PET scans showed bilateral presynaptic dopaminergic dysfunction without marked lateralization. Molecular genetic analysis showed identical chromosome 6 haplotypes inherited by affected subjects, with alternate allelic deletions of parkin exons 3 and 4. Furthermore, mRNA analyses identified aberrantly spliced parkin transcripts, suggesting that unusual parkin protein isoforms may be expressed in the brain and retain some function.

The human sideroflexin 5 (SFXN5) gene: sequence, expression analysis and exclusion as a candidate for PARK3.

Parkinson's disease (PD) is a common neurodegenerative disorder with clinical features of bradykinesia, rigidity and resting tremor resulting from the deficiency of dopamine in the nigrostriatal system. Previously we mapped a susceptibility gene for an autosomal dominant form of PD to a 10.6 cM region of chromosome 2p (PARK3; OMIM 602404). Here we report the identification and characterization of the human sideroflexin 5 gene (SFXN5), which maps to the critical PARK3 region. Database analysis and 5'-RACE (rapid amplification of cDNA ends) identified a 4191 bp cDNA, encoding a predicted protein of 340 amino acids. The genomic sequence and structure of SFXN5 confirmed the cDNA sequence. Northern blot analysis revealed a single SFXN5 transcript of approximately 4.3 kb, which was primarily expressed in the brain. An examination of SFXN5 expression in specific regions of the human brain revealed high levels of expression in all regions analyzed. Sequence analysis of 2p13 linked individuals affected with PD did not reveal any potentially pathogenic mutations within SFXN5, suggesting SFXN5 does not correspond to PARK3.