The G6055A (G2019S) mutation in LRRK2 is frequent in both early and late onset Parkinson's disease and originates from a common ancestor.

BACKGROUND: Mutations in the gene Leucine-Rich Repeat Kinase 2 (LRRK2) were recently identified as the cause of PARK8 linked autosomal dominant Parkinson's disease. OBJECTIVE: To study recurrent LRRK2 mutations in a large sample of patients from Italy, including early (<50 years) and late onset familial and sporadic Parkinson's disease. RESULTS: Among 629 probands, 13 (2.1%) were heterozygous carriers of the G2019S mutation. The mutation frequency was higher among familial (5.1%, 9/177) than among sporadic probands (0.9%, 4/452) (p<0.002), and highest among probands with one affected parent (8.7%, 6/69) (p<0.001). There was no difference in the frequency of the G2019S mutation in probands with early v late onset disease. Among 600 probands, one heterozygous R1441C but no R1441G or Y1699C mutations were detected. None of the four mutations was found in Italian controls. Haplotype analysis in families from five countries suggested that the G2019S mutation originated from a single ancient founder. The G2019S mutation was associated with the classical Parkinson's disease phenotype and a broad range of onset age (34 to 73 years). CONCLUSIONS: G2019S is the most common genetic determinant of Parkinson's disease identified so far. It is especially frequent among cases with familial Parkinson's disease of both early and late onset, but less common among sporadic cases. These findings have important implications for diagnosis and genetic counselling in Parkinson's disease.

Early-onset parkinsonism associated with PINK1 mutations: frequency, genotypes, and phenotypes.

OBJECTIVE: To assess the prevalence, nature, and associated phenotypes of PINK1 gene mutations in a large series of patients with early-onset (<50 years) parkinsonism. METHODS: The authors studied 134 patients (116 sporadic and 18 familial; 77% Italian) and 90 Italian controls. The whole PINK1 coding region was sequenced from genomic DNA; cDNA was analyzed in selected cases. RESULTS: Homozygous pathogenic mutations were identified in 4 of 90 Italian sporadic cases, including the novel Gln456Stop mutation; single heterozygous truncating or missense mutations were found in another 4 Italian sporadic cases, including two novel mutations, Pro196Leu and Gln456Stop. Pathogenic mutations were not identified in the familial cases. Novel (Gln115Leu) and known polymorphisms were identified with similar frequency in cases and controls. In cases carrying single heterozygous mutation, cDNA analysis detected no additional mutations, and revealed a major pathogenic effect at mRNA level for the mutant C1366T/Gln456Stop allele. All patients with homozygous mutations had very early disease onset, slow progression, and excellent response to l-dopa, including, in some, symmetric onset, dystonia at onset, and sleep benefit, resembling parkin-related disease. Phenotype in patients with single heterozygous mutation was similar, but onset was later. CONCLUSIONS: PINK1 homozygous mutations are a relevant cause of disease among Italian sporadic patients with early-onset parkinsonism. The role of mutations found in single heterozygous state is difficult to interpret. Our study suggests that, at least in some patients, these mutations are disease causing, in combination with additional, still unknown factors.

Phosphorylated 14-3-3zeta protein in the CSF of neuroleptic-treated patients.

The authors describe 12 neuroleptic-treated patients with dementia of various etiologies who showed CSF elevation of phosphorylated 14-3-3zeta and normal tau protein levels. This contrasted with elevated amounts of 14-3-3 gamma, epsilon, and unphosphorylated zeta coupled to high tau protein levels in Creutzfeldt-Jakob disease and negative 14-3-3 assay in drug-free patients with dementia. Characterization of CSF 14-3-3 isoforms and determination of tau protein level can help to distinguish different etiologies of dementia.

Autosomal recessive early onset parkinsonism is linked to three loci: PARK2, PARK6, and PARK7.

Autosomal recessive, early onset parkinsonism (AREP) is genetically heterogeneous. Mutations in the parkin gene (PARK2 locus, chromosome 6q) account for up to 50% of AREP families. The parkin protein displays ubiquitin-ligase activity for different targets, which accumulate in the brain of patients with parkin defect and might cause neurodegeneration. Two new AREP loci (PARK6 and PARK7) have been recently mapped on chromosome 1p and confirmed in independent datasets, suggesting that both might be frequent. The three AREP forms display similar clinical phenotypes. Recruiting new families will help cloning the defective genes at PARK6 and PARK7 loci. This will contribute to unraveling the pathogenesis of AREP, and it is also expected to foster our understanding of molecular events underlying classic Parkinson's disease.

Antioxidant properties of clozapine and related neuroleptics.

The antioxidant properties of clozapine and other related molecules were evaluated with the crocin bleaching test both in aqueous and non-aqueous environment. The tests of microsomal lipid peroxidation and carbonyl formation were also used. In aqueous solution, chlorpromazine and trifluoperazine appear particularly effective in the bleaching of crocin, while serotonin has an efficacy intermediate between those of phenothiazines and clozapine. The latter drug, on the other hand, in a non-aqueous medium shows an antioxidant power comparable to that of butylated hydroxytoluene, indicating that its antioxidant properties are better expressed in a hydrophobic environment of the type present in a biological membrane. In fact, in lipid peroxidation induced in microsomal membranes, clozapine, chlorpromazine, trifluoperazine and serotonin act as very good antioxidants; at low concentrations, clozapine appears to be the most efficient after butylated hydroxytoluene. Similarly, all these compounds markedly inhibit protein carbonyl formation, clozapine being one of the most efficient. Thus, under different in vitro experimental conditions, the neuroleptic drugs chlorpromazine and trifluoperazine and the antipsychotic substance clozapine act as very effective antioxidants; this property might, at least in part, be responsible for the physiological and clinical effects observed in vivo.

Decrease of serum malondialdehyde in patients treated with chlorpromazine.

Malondialdehyde determination in serum from schizophrenic patients before and after treatment with chlorpromazine showed that, after treatment, patients had significantly lower values than before. The antioxidant properties of chlorpromazine can be related to its effect on the level of serum lipid peroxides and possibly to its neuroleptic action.