Brice, A.

Cerebellar ataxia with elevated cerebrospinal free sialic acid (CAFSA) (Article)

2009-03-01T00:00:00Z

In order to identify new metabolic abnormalities in patients with complex neurodegenerative disorders of unknown aetiology, we performed high resolution in vitro proton nuclear magnetic resonance spectroscopy on patient cerebrospinal fluid (CSF) samples. We identified five adult patients, including two sisters, with significantly elevated free sialic acid in the CSF compared to both the cohort of patients with diseases of unknown aetiology (n 144; P < 0.001) and a control group of patients with well-defined diseases (n 91; P < 0.001). All five patients displayed cerebellar ataxia, with peripheral neuropathy and cognitive decline or noteworthy behavioural changes. Cerebral MRI showed mild to moderate cerebellar atrophy (5/5) as well as white matter abnormalities in the cerebellum including the peridentate region (4/5), and at the periventricular level (3/5). Two-dimensional gel analyses revealed significant hyposialylation of transferrin in CSF of all patients compared to age-matched controls (P < 0.001)a finding not present in the CSF of patients with Salla disease, the most common free sialic acid storage disorder. Free sialic acid content was normal in patients' urine and cultured fibroblasts as were plasma glycosylation patterns of transferrin. Analysis of the ganglioside profile in peripheral nerve biopsies of two out of five patients was also normal. Sequencing of four candidate genes in the free sialic acid biosynthetic pathway did not reveal any mutation. We therefore identified a new free sialic acid syndrome in which cerebellar ataxia is the leading symptom. The term CAFSA is suggested (cerebellar ataxia with free sialic acid).

Phenotype, genotype, and worldwide genetic penetrance of LRRK2-associated Parkinson's disease: a case-control study (Article)

2008-07-01T00:00:00Z

Background: Mutations in LRRK2, the gene that encodes leucine-rich repeat kinase 2, are a cause of Parkinson's disease (PD). The International LRRK2 Consortium was established to answer three key clinical questions: can LRRK2-associated PD be distinguished from idiopathic PD; which mutations in LRRK2 are pathogenic; and what is the age-specific cumulative risk of PD for individuals who inherit or are at risk of inheriting a deleterious mutation in LRRK2? Methods: Researchers from 21 centres across the world collaborated on this study. The frequency of the common LRRK2 Gly2019Ser mutation was estimated on the basis of data from 24 populations worldwide, and the penetrance of the mutation was defined in 1045 people with mutations in LRRK2 from 133 families. The LRRK2 phenotype was defined on the basis of 59 motor and non-motor symptoms in 356 patients with LRRK2-associated PD and compared with the symptoms of 543 patients with pathologically proven idiopathic PD. Findings: Six mutations met the consortium's criteria for being proven pathogenic. The frequency of the common LRRK2 Gly2019Ser mutation was 1% of patients with sporadic PD and 4% of patients with hereditary PD; the frequency was highest in the middle east and higher in southern Europe than in northern Europe. The risk of PD for a person who inherits the LRRK2 Gly2019Ser mutation was 28% at age 59 years, 51% at 69 years, and 74% at 79 years. The motor symptoms (eg, disease severity, rate of progression, occurrence of falls, and dyskinesia) and non-motor symptoms (eg, cognition and olfaction) of LRRK2-associated PD were more benign than those of idiopathic PD. Interpretation: Mutations in LRRK2 are a clinically relevant cause of PD that merit testing in patients with hereditary PD and in subgroups of patients with PD. However, this knowledge should be applied with caution in the diagnosis and counselling of patients. Funding: UK Medical Research Council; UK Parkinson's Disease Society; UK Brain Research Trust; Internationaal Parkinson Fonds; Volkswagen Foundation; National Institutes of Health: National Institute of Neurological Disorders and Stroke and National Institute of Aging; Udall Parkinson's Disease Centre of Excellence; Pacific Alzheimer Research Foundation Centre; Italian Telethon Foundation; Fondazione Grigioni per il Morbo di Parkinson; Michael J Fox Foundation for Parkinson's Research; Safra Global Genetics Consortium; US Department of Veterans Affairs; French Agence Nationale de la Recherche.

Biological effects of the PINK1 c.1366C>T mutation: Implications in Parkinson disease pathogenesis (Article)

2007-04-01T00:00:00Z

PINK1 gene mutations are a cause of recessively inherited, early-onset Parkinson's disease. In some patients, a single heterozygous mutation has been identified, including the recurrent c.1366C>T transition. The interpretation of this finding remains controversial. Furthermore, the c.1366C>T mutation is associated with lower levels of PINK1 transcript, raising the question of whether mRNA levels correlate with the clinical status. We sequenced genomic DNA and copy DNA (cDNA) from 20 subjects carrying the c.1366C>T mutation in the homozygous (n=5) or heterozygous (n=15) state. In 17 mutation carriers, messenger RNA (mRNA) was quantified by real-time PCR using four different assays (PINK1 exon 5-6 or exon 7-8 relative to control genes SDHA or YWHAZ). Genomic sequencing confirmed the presence and zygosity of PINK1 mutations. cDNA sequencing in heterozygous mutation carriers revealed a strong wild-type and a much weaker or almost absent mutant signal, whereas in the homozygous patients, only the mutant signal was detected. Homozygous and heterozygous carriers showed PINK1 mRNA levels relative to a reference gene in the range of 0.1-0.2 and 0.5-0.6, respectively, compared with values of 0.9-1.0 in mutation-negative individuals. Treatment of lymphoblasts from a heterozygous mutation carrier with cycloheximide markedly increased the mutant transcript signal. We conclude that the recurrent PINK1 c.1366C>T mutation exerts a major effect at the mRNA level (80-90% reduction), most likely via nonsense-mediated mRNA decay. The absence of correlation between PINK1 mRNA levels and clinical status in heterozygous mutation carriers suggests that other genetic or environmental factors play a role in determining the phenotypic variability associated with the c.1366C>T mutation.

DJ-1( PARK7), a novel gene for autosomal recessive, early onset parkinsonism (Article)

2003-10-01T00:00:00Z

Four chromosomal loci ( PARK2, PARK6, PARK7, and PARK9) associated with autosomal recessive, early onset parkinsonism are known. We mapped the PARK7 locus to chromosome 1p36 in a large family from a genetically isolated population in the Netherlands, and confirmed this linkage in an Italian family. By positional cloning within the refined PARK7 critical region we recently identified mutations in the DJ-1 gene in the two PARK7-linked families. The function of DJ-1 remains largely unknown, but evidence from genetic studies on the yeast DJ-1 homologue, and biochemical studies in murine and human cell lines, suggests a role for DJ-1 as an antioxidant and/or a molecular chaperone. Elucidating the role of DJ-1 will lead to a better understanding of the pathogenesis of DJ-1-related and common forms of Parkinson's disease.