Lack of association of neprilysin gene polymorphisms with Alzheimer's disease in a southern Chinese community.

BACKGROUND: Increasing evidence suggests that neprilysin (NEP) may be the major degrading enzyme of amyloid beta (Abeta) in the brain and the NEP gene has been proposed as a candidate gene for Alzheimer's disease (AD). Association results between the NEP gene and AD are still preliminary. This study investigates the effect of the polymorphisms of -204G/C and 159C/T in the NEP gene on the development of sporadic Alzheimer's disease (SAD) in a southern Chinese community. METHOD: 236 sporadic late-onset AD patients were recruited from Guangzhou Psychiatric Hospital in southern China, and 332 healthy elderly controls were enrolled from three old age homes in suburban Guangzhou. NEP and ApoE genotype were determined by PCR-RFLP. RESULTS: No differences in genotypic and allelic frequencies of -204G/C and 159C/T polymorphisms in NEP were found between AD and control group (for -204G/C genotype: chi2 = 2.34, P > 0.05; for allele: chi2 = 2.31, P > 0.05; for 159C/T genotype: chi2 = 1.34, P > 0.05; for allele: chi2 = 0.88, P > 0.05). Neither was any difference found in genotypic and allelic frequency when stratified by sex or by ApoE epsilon4 allele (P > 0.05). CONCLUSIONS: Our results suggest that -204G/C and 159C/T polymorphisms of the NEP gene may not be associated with SAD. Moreover, both sex and ApoE epsilon4 allele do not affect the distribution of NEP gene polymorphisms.