Creutzfeldt-Jakob disease with tubulovesicular structures: an ultrastructural study.

Tubulovesicular structures (TVS) have been consistently observed in brain tissue of the transmissible spongiform virus encephalopathies such as natural and experimental scrapie, bovine spongiform encephalopathy and experimentally induced Creutzfeldt-Jakob disease (CJD). TVS were recently demonstrated in 3 cases of naturally occurring CJD. We report here the presence of TVS in another human brain with CJD, as detected in all 3 specimens by thin section electron microscopy. Their occurrence in all types of spongiform encephalopathies, irrespective of the affected host and the strain of infectious agent, emphasizes their biological significance.     

TOMM40 rs10524523 polymorphism's role in late-onset Alzheimer's disease and in longevity

Recently, it has been reported that TOMM40 variable-length poly-T sequence polymorphism (rs10524523) in combination with APOE alleles (E2, E3, E4) significantly influences late-onset Alzheimer's disease (LOAD) age of onset. In a group of 414 LOAD patients, 173 centenarians and 305 neurologically healthy individuals, we investigated the impact of TOMM40 poly-T tracts on LOAD incidence, age of onset, and longevity. TOMM40 allelic variants were classified into four categories: short (S; 14-16T), long a (La; 20-22T), long b (Lb; 26-30T), and very long (VL; 31-39T). Our results demonstrate that La and Lb share similar characteristics in affecting LOAD risk, thus for some analyses they were combined into L category. We observed significantly lower frequency of VL allele (p < 0.0001) and significantly higher frequency of L alleles in the LOAD patients compared to the control individuals (p < 0.0001). S/S, S/VL, and VL/VL genotypes and VL-E2, S-E3, VL-E3 haplotypes are significantly associated with lower LOAD risk. VL-E3 haplotype carriers significantly more frequently developed LOAD when they were ≥79 years old. Additionally, S/L genotype is associated with a significantly increased LOAD risk (p < 0.0001). We conclude that in the carriers of TOMM40-APOE haplotypes comprising E4 allele, the TOMM40 rs10524523 allele does not play substantial role in establishing LOAD risk. Nevertheless, TOMM40 L allele increases the risk when E4 is absent. Finally, L allele, as well as genotypes (S/L, V/L) and haplotypes (L-E3, L-E4) comprising L significantly reduce the likelihood of living up to 100 years.     

Sigma receptor type 1 gene variation in a group of Polish patients with Alzheimer's disease and mild cognitive impairment

The sigma-1 receptor (SIGMAR1) is a subtype of a nonopioid sigma receptor family and is implicated in numerous functions connected with Alzheimer's disease (AD). Two common genetic variants were identified in SIGMAR1: GC-241 -240TT and Q2P (A61C). It was suggested that the TT-C haplotype is a protective factor for AD. We decided to investigate a putative link between the variants of SIGMAR1 and AD in a group of Polish patients with late-onset AD, in patients with mild cognitive impairment, and in a control group. We observed no significant differences for the SIGMAR1 allele, genotype, haplotype, and diplotype distributions between the studied groups. Multivariate logistic regression analysis showed no interaction between the APOE4 and SIGMAR1 polymorphisms. Further studies using data from different populations are required to elucidate the effect of SIGMAR1 polymorphisms on AD.     

Hyperhomocysteinemia and methylenetetrahydrofolate reductase polymorphism in patients with Parkinson's disease

Elevated levels of homocysteine have been observed in Parkinson's disease (PD) patients treated with levodopa. However, it is not studied if duration of PD or PD per se is associated with hyperhomocysteinemia. In the present study, the levels of homocysteine in 99 levodopa-treated PD patients, 15 untreated PD patients and 100 controls were examined. We focused on the influence of levodopa dose, duration of therapy and disease as well as genetic (C677T methylenetetrahydrofolate reductase (MTHFR) polymorphism) and environmental factors. We found that levodopa-treated PD patients had elevated homocysteine plasma levels as compared to controls (p < 0.05), but the levels did not depend on levodopa doses. Another factor influencing homocysteine level was the duration of PD (p < 0.001). The frequency of allele C677T of MTHFR gene did not differ between PD and controls. In conclusion, hyperhomocysteinemia is associated with the duration of PD and levodopa treatment and possibly also with PD per se.     

Dopamine beta-hydroxylase -1021C>T association and Parkinson's disease

A single nucleotide polymorphism in the promoter region of the dopamine beta-hydroxylase gene (DBH -1021C>T; rs1611115) is reported to regulate plasma enzyme activity levels. This variant has also been the focus of two large association studies in Parkinson's disease yielding conflicting results. We examined this association in four Caucasian patient-control series (n=2696). A modest protective association was observed in the Norwegian series (OR=0.81, p=0.03; n=1676), however, the effect was in the opposite direction in the Polish series (OR=2.01, p=0.01; n=224). No association was observed for DBH -1021C>T with disease susceptibility in the US and Irish series, or combining all four series (OR=0.91, p=0.16, n=2696). We observed a modest association between DBH -1021C>T and AAO in the combined series (p=0.01). Taken together, these findings indicate that DBH -1021C>T does not play a major role in the pathogenesis of Parkinson's disease.