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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.

Objective: To determine whether reported genetic association of polymorphisms in the CYP2D6, CYP1A1, N-acetyltransferase 2 (NAT2), DAT1, and glutathione s-transferase M1 (GSTM1) genes with PD were evident in a population of 176 unrelated patients with sporadic PD and to extend these findings to other disease groups (familial PD [n = 30], ALS [n = 50], multiple system atrophy [n = 38], progressive supranuclear palsy [n = 35], and AD [n = 23])., Methods: A combination of allele-specific PCR and analysis of restriction fragment length polymorphisms were performed., Results: We genotyped 1,131 individuals. After matching each patient with a control subject by age, sex, ethnicity, and geographic origin, there was no association of any allele/genotype with any of the six disease groups. There was an increased frequency of NAT2 slow acetylators in the ALS group compared with controls (70% versus 50%; OR 2.33 [95% CI, 1.03 to 5.30]), but this was not significant after adjusting for multiple testing., Conclusions: This is one of the most extensive candidate gene studies performed in PD and the first time that some of these loci have been studied in multiple system atrophy and progressive supranuclear palsy. In contrast with previous studies, we found no role for these polymorphisms in the etiology of PD, ALS, multiple system atrophy, progressive supranuclear palsy, or AD.

Objective: To confirm whether a dinucleotide repeat sequence in an intron of the microtubule-associated protein tau is associated with progressive supranuclear palsy (PSP) in an independent study population and to establish an improved methodology for allelotyping., Background: It has recently been reported that a genetic variant of tau, known as the A0 allele, was represented excessively in PSP patients when compared with control subjects., Methods: In a multicenter study, the authors examined the allelic distribution of this dinucleotide repeat marker in a set of clinically ascertained PSP patients (n = 30), multiple system atrophy (MSA) patients (n = 35), and matched control subjects (n = 70). Individuals were allelotyped using automated analysis of fluorescently labeled PCR products., Results: The A0 allele was significantly overrepresented in the PSP patients (93.3% versus 76.4%; p = 0.0067; odds ratio [OR] = 4.33; 95% confidence interval [CI], 1.36 to 13.60), but not in the MSA patients. Likewise, A0 homozygotes were overrepresented in the PSP group (86.7% versus 61.1%; p = 0.02; OR = 4.14; 95% CI, 1.19 to 14.48) compared with control subjects., Conclusions: The findings of this study, which is the largest to date, support those of a previous investigation that used pathologically confirmed PSP patients. These data provide additional strong evidence that genetic variation at or near the tau gene plays an important role in the pathogenesis of PSP.