Association of BACE1 Gene Polymorphism with Cerebellar Volume but Not Cognitive Function in Normal Individuals

Association of G/C (rs638405) Polymorphism in β-secretase Gene with Alzheimer's Disease

BACKGROUND

Alzheimer's Disease (AD) is a neurodegenerative disorder, which is the most common cause of dementia in the elderly. Accumulation of β-amyloid plaques outside neurons is the most important pathological hallmark of AD, which is produced by cleavage of amyloid precursor protein by the Alzheimer's β-secretase (BACE1). Since BACE1 is a key enzyme in the formation of β-amyloid peptides, the purpose of this study was to assess the association between polymorphisms of G/C (rs638405) BACE1 gene with sporadic AD in Khuzestan, Isfahan and Fars provinces in Iran.

METHODS

Genotypes were determined by the PCR-Restriction Fragment Length Polymorphism (PCR-RFLP) technique in two groups including 89 sporadic AD patients and 73 healthy subjects.

RESULTS

The findings of the BACE1 G/C (rs638405) polymorphism revealed that there was no significant difference between AD patients and controls in men group; however, there was a weak difference in the frequency of CC genotype between patients and controls in women group (χ 2=3.333, df=1, p=0.068).

CONCLUSION

The results of this study suggest that the G/C (rs638405) polymorphism of BACE1 gene might not be related with sporadic AD in Khuzestan, Isfahan and Fars provinces in Iran. However, our results do not support a genetic risk factor of this polymorphism for developing AD in male group of this study.

Brain MR Imaging Findings of Cardiac-Type Fabry Disease with an IVS4+919G>A Mutation

BACKGROUND AND PURPOSE

A high incidence of cardiac-type Fabry disease with an α-galactosidase A mutation, IVS4 + 919 G>A, has been identified in the Taiwanese population. The neurologic manifestation has not been understood in this specific cardiac variant. This study aimed to investigate the typical imaging features of classic Fabry disease in patients with IVS4 Fabry disease.

MATERIALS AND METHODS

Twenty-six patients with IVS4-type Fabry disease (20 men and 6 women; age range, 43-71 years; median age, 61 years) and 26 age- and sex-matched healthy controls (age range, 44-68 years; median age, 60 years) were analyzed for white matter hyperintensities, the pulvinar sign, and basilar artery diameter. The volumes of white matter hyperintensities were calculated by comparison with an in-house data base of 276 controls.

RESULTS

Infarctions were found in 9 patients with IVS4 Fabry disease (35%) and in none of the healthy controls (P = .001). A pulvinar sign was found in 8 patients with IVS4 Fabry disease (30%) and in none of the healthy controls (P = .002). No significant difference was found in Fazekas scale scores for white matter hyperintensities; however, white matter hyperintensity volume in the deep white matter was higher in patients with IVS4 Fabry disease than in those from the healthy control data base (P = .004).

CONCLUSIONS

Along with its involvement of the cardiac system, IVS4-type Fabry disease has features similar to those of classic Fabry disease and a higher frequency of deep white matter hyperintensities and a higher incidence of infarctions and pulvinar signs than in healthy controls.

The association of RAB18 gene polymorphism (rs3765133) with cerebellar volume in healthy adults

Genetic factors are responsible for the development of the human brain. Certain genetic factors are known to increase the risk of common brain disorders and affect the brain structure. Therefore, even in healthy people, these factors have a role in the development of specific brain regions. Loss-of-function mutations in the RAB18 gene (RAB18) cause Warburg Micro syndrome, which is associated with reduced brain size and deformed brain structures. In this study, we hypothesized that the RAB18 variant might influence regional brain volumes in healthy people. The study participants comprised 246 normal volunteers between 21 and 59 years of age (mean age of 37.8 ± 12.0 years; 115 men, 131 women). Magnetic resonance imaging (MRI) and genotypes of RAB18 rs3765133 were examined for each participant. The differences in regional brain volumes between T homozygotes and A-allele carriers were tested using voxel-based morphometry. The results showed that RAB18 rs3765133 T homozygote group exhibited larger gray matter (GM) volume in the left middle temporal and inferior frontal gyrus of the cerebrum than the A-allele carriers. An opposite effect was observed in both the posterior lobes and right tonsil of the cerebellum, in which the GM volume of RAB18 rs3765133 T homozygotes was smaller than that of the A-allele carriers (all P FWE < 0.05). Our findings suggest that RAB18 rs3765133 polymorphism affects the deve-lopment of specific brain regions, particularly the cerebellum, in healthy people.