Dataset Information

Characterization of PLA2G6 as a locus for dystonia-parkinsonism.

ABSTRACT:

Background

Although many recessive loci causing parkinsonism dystonia have been identified, these do not explain all cases of the disorder.

Methods

We used homozygosity mapping and mutational analysis in three individuals from two unrelated families who presented with adult-onset levodopa-responsive dystonia-parkinsonism, pyramidal signs and cognitive/psychiatric features, and cerebral and cerebellar atrophy on magnetic resonance imaging but absent iron in the basal ganglia.

Results

We identified areas of homozygosity on chromosome 22 and, subsequently, PLA2G6 mutations.

Interpretation

PLA2G6 mutations are associated with infantile neuroaxonal dystrophy and have been reported previously to cause early cerebellar signs, and the syndrome was classified as neurodegeneration with brain iron accumulation (type 2). Our cases have neither of these previously pathognomic features. Thus, mutations in PLA2G6 should additionally be considered in patients with adult-onset dystonia-parkinsonism even with absent iron on brain imaging.

SUBMITTER: Paisan-Ruiz C

PROVIDER: S-EPMC9016626 | biostudies-literature | 2009 Jan

REPOSITORIES: biostudies-literature

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Publications

Characterization of PLA2G6 as a locus for dystonia-parkinsonism.

Paisan-Ruiz Coro C Bhatia Kailash P KP Li Abi A Hernandez Dena D Davis Mary M Wood Nick W NW Hardy John J Houlden Henry H Singleton Andrew A Schneider Susanne A SA

Annals of neurology 20090101 1

<h4>Background</h4>Although many recessive loci causing parkinsonism dystonia have been identified, these do not explain all cases of the disorder.<h4>Methods</h4>We used homozygosity mapping and mutational analysis in three individuals from two unrelated families who presented with adult-onset levodopa-responsive dystonia-parkinsonism, pyramidal signs and cognitive/psychiatric features, and cerebral and cerebellar atrophy on magnetic resonance imaging but absent iron in the basal ganglia.<h4>Re ...[more]

PMID: 18570303

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Project description:IntroductionPhospholipase A2 Group VI (PLA2G6), encoding calcium-independent phospholipase A2, has been isolated as the gene responsible for an autosomal recessive form of early-onset Parkinson's disease (namely, PARK14). Compared to idiopathic Parkinson's disease (iPD), PARK14 has several atypical clinical features. PARK14 has an earlier age at onset and is more likely to develop levodopa-induced dyskinesia. In iPD, serum metabolomics has observed alterations in several metabolic pathways that are related to disease status and clinical manifestations. This study aims to describe the serum metabolomics features of patients with PARK14.DesignThis case-control biomarker study tested nine patients diagnosed with PARK14. Eight age and sex-matched healthy subjects were recruited as controls. To evaluate the influence of single heterozygous mutation, we enrolled eight healthy one-degree family members of patients with PARK14, two patients diagnosed with early-onset Parkinson's disease (EOPD) who had only a single heterozygous PLA2G6 mutation, and one patient with EOPD without any known pathogenic mutation.MethodsThe diagnosis of PARK14 was made according to the diagnostic criteria for Parkinson's disease (PD) and confirmed by genetic testing. To study the serum metabolic features, we analyzed participants' serum using UHPLC-QTOF/MS analysis, a well-established technology.ResultsWe quantified 50 compounds of metabolites from the serum of all the study subjects. Metabolites alterations in serum had good predictive accuracy for PARK14 diagnosis (AUC 0.903) and advanced stage in PARK14 (AUC 0.944). Of the 24 metabolites that changed significantly in patients' serum, eight related to lipid metabolism. Oleic acid and xanthine were associated with MMSE scores. Xanthine, L-histidine, and phenol correlated with UPDRS-III scores. Oleic acid and 1-oleoyl-L-alpha-lysophosphatidic acid could also predict the subclass of the more advanced stage in the PLA2G6 Group in ROC models.ConclusionThe significantly altered metabolites can be used to differentiate PLA2G6 pathogenic mutations and predict disease severity. Patients with PLA2G6 mutations had elevated lipid compounds in C18:1 and C16:0 groups. The alteration of lipid metabolism might be the key intermediate process in PLA2G6-related disease that needs further investigation.

Project description:BackgroundMutations in the PLA2G6 gene have been identified in autosomal recessive neurodegenerative diseases classified as infantile neuroaxonal dystrophy (INAD), neurodegeneration with brain iron accumulation (NBIA), and dystonia-parkinsonism. These clinical syndromes display two significantly different disease phenotypes. NBIA and INAD are very similar, involving widespread neurodegeneration that begins within the first 1-2 years of life. In contrast, patients with dystonia-parkinsonism present with a parkinsonian movement disorder beginning at 15 to 30 years of age. The PLA2G6 gene encodes the PLA2G6 enzyme, also known as group VIA calcium-independent phospholipase A(2), which has previously been shown to hydrolyze the sn-2 acyl chain of phospholipids, generating free fatty acids and lysophospholipids.Methodology/principal findingsWe produced purified recombinant wildtype (WT) and mutant human PLA2G6 proteins and examined their catalytic function using in vitro assays with radiolabeled lipid substrates. We find that human PLA2G6 enzyme hydrolyzes both phospholipids and lysophospholipids, releasing free fatty acids. Mutations associated with different disease phenotypes have different effects on catalytic activity. Mutations associated with INAD/NBIA cause loss of enzyme activity, with mutant proteins exhibiting less than 20% of the specific activity of WT protein in both lysophospholipase and phospholipase assays. In contrast, mutations associated with dystonia-parkinsonism do not impair catalytic activity, and two mutations produce a significant increase in specific activity for phospholipid but not lysophospholipid substrates.Conclusions/significanceThese results indicate that different alterations in PLA2G6 function produce the different disease phenotypes of NBIA/INAD and dystonia-parkinsonism. INAD/NBIA is caused by loss of the ability of PLA2G6 to catalyze fatty acid release from phospholipids, which predicts accumulation of PLA2G6 phospholipid substrates and provides a mechanistic explanation for the accumulation of membranes in neuroaxonal spheroids previously observed in histopathological studies of INAD/NBIA. In contrast, dystonia-parkinsonism mutations do not appear to directly impair catalytic function, but may modify substrate preferences or regulatory mechanisms for PLA2G6.

Dataset Information

Characterization of PLA2G6 as a locus for dystonia-parkinsonism.

Background

Methods

Results

Interpretation

Publications

Characterization of PLA2G6 as a locus for dystonia-parkinsonism.

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