This invention is directed to a DNA sequence comprising a nucleotide sequence encoding a variant paraoxonase protein and to said variant paraoxonase protein as well as a method and a kit for detecting a risk of cancer, coronary or cerebrovascular disease, hypertension, type 2 diabetes, dementia, joint arthrosis, cataract, or sensitivity to organophosphorus compounds in a subject, the method comprising isolating genomic DNA from said subject, determining the allelic pattern for the codon 102 of the paraoxonase encoding PON1 gene in the genomic DNA, identification of Ile101Val mutation indicating said risk being increased and for targeting paraoxonase activity modulating therapies. Further this invention relates to transgenic animals comprising a human DNA molecule encoding said variant paraoxonase and to a method of phenotype-targeted gene sequencing.