Abstract: The present invention provides a method for the in vitro diagnosis of dementia with Lewy bodies in a human patient comprising the step of determining the amount of transcripts SNCAtv3 (SEQ ID NO: 3) and SNCAtv2 (SEQ ID NO: 2) of the human alpha-synuclein gene (SNCA) in a biological sample obtained from the patient, wherein when the amount of both transcripts determined for the patient is reduced with respect to a reference value, this is indicative of the presence of dementia with Lewy bodies in the patient. The invention further provides means to determine the amount of said transcripts, as well as a method to stablish the response of a patient which has been diagnosed with dementia with Lewy bodies to a medical regime for its treatment by determining the amount of transcripts SNCAtv3 and SNCAtv2 in a biological sample from the patient before and after the treatment.

Abstract: Specific polymorphisms in BChE gene have been found which allow determining whether a patient suffers from dementia with Lewy bodies (DLB), and allow distinguishing it from Alzheimer's disease. The invention provides an in vitro method for the diagnosis of DLB comprising determining in a biological sample from a subject, the genotype of the following polymorphisms in butyrylcholinesterase (BChE) gene: the polymorphic site at position 3687 in NCBI Accession Number NG_009031 (i.e. SEQ ID NO: 1) the polymorphic site at position 4206 in SEQ ID NO: 1, the polymorphic site at position 4443 in SEQ ID NO: 1. and the polymorphic site at position 68974 in NCBI Accession Number NG_009031 (i.e. position 934 in SEQ ID NO: 26).

Abstract: Specific alterations in BChE gene have been found which allow determining whether a patient suffers from dementia with Lewy bodies (DLB), and allow distinguishing it from Alzheimer's disease. The invention provides an in vitro method for the diagnosis of DLB comprising determining in a biological sample from a subject, the genotype of the following alterations in butyrylcholinesterase (BChE) gene: the polymorphic sites at position 68974 in NCBI Accession Number NG_009031 (i.e. position 934 in SEQ ID NO: 28), and the polymorphic sites 3687, 4206, 4443, and the poly-thymine region at positions 4780 to 4786, said positions with reference to NCBI Accession Number NG_009031 (i.e. positions 3687, 4206 and 4443 respectively in SEQ ID NO: 1), which corresponds to the nucleotide sequence of human BChE gene.