Genotyping of 38 insertion/deletion polymorphisms for human identification using universal fluorescent PCR.

Short insertion/deletion (Indel) polymorphisms of approximately 2-6 bp are useful as biallelic markers for forensic analysis, and the application of Indel genotyping as a supplementary tool would improve human identification accuracy. We examined the allele frequencies of 37 autosomal Indels in the Japanese population and developed a novel dual-color genotyping method for human identification on the basis of universal fluorescent PCR, including the sex-typing amelogenin locus. Target genomic fragment sizes for 38 Indels were 49-143 bp. We analyzed these Indels in 100 Japanese individuals using the M13(-47) sequence as a universal primer. For dual-color genotyping, we designed a novel universal primer with high amplification efficiency and specificity. Using FAM-labeled M13(-47) and HEX-labeled modified M13(-47) primers, fluorescent signals at all loci were clearly distinguished in two independent multiplex PCRs. Average minor allele frequency was 0.39, and accumulated matching probability was 2.12 × 10(-15). Complete profiles were successfully amplified with as little as 0.25 ng of DNA. This method provides robust, sensitive, and cost-effective genotyping for human identification.

Genotyping of cytochrome p450 isoform genes is useful for forensic identification of cadaver.

Tailor-made medical treatment based on the polymorphism of genes encoding drug-metabolizing enzymes has been advocated and is being tried on an experimental basis at numerous centers. If DNA polymorphism analysis becomes routine in tailor-made medical treatment, it will be very useful in forensic identification. In this study, we determined the genotype frequencies of five p450 (CYP) isoform genes, CYP1A2, CYP2D6, CYP2E1, CYP2C9 and CYP2C19 in 196 Japanese individuals to evaluate their forensic usefulness. These genes encode the most important enzymes among the CYP superfamily that metabolize clinically used drug. The frequency of each allele agreed well with those reported previously and their genotype frequencies did not deviate from those expected from Hardy-Weinberg equilibrium. CYP2C subfamilies such as CYP2C9 and CYP2C19 on chromosome 10 showed high sequence homology, as high as over 95% in the regions flanking polymorphic sites. Although 3240 genotype combinations of these five CYP isoform genes are theoretically possible, 101 combinations were detected in this study. The genotype frequencies of these five isoform genes excluded their linkage. The following two genotype combinations showed the highest frequency of 0.036: CYP1A2*1A/*1A, CYP2D6*1/*10, CYP2E1*1/*1, CYP2C9*1/*1 and CYP2C19*1/*1 and CYP1A2*1A/*1C, CYP2D6*1/*10, CYP2E1*1/*1, CYP2C9*1/*1 and CYP2C19*1/*1. Thus, genotyping of CYP isoform genes should be useful in forensic identification.

Simultaneous analyses of hypoglycemic agents and C-peptide are essential in a homicide case with the combined dosing insulin and insulin-releasing drug.

A 5-year-old girl was given a sulfonylurea hypoglycemic agent, 25 mg of glibenclamide (ten tablets of Euglucon) with two benzodiazepine drugs, 2 mg of estazoram and 0.75 mg of triazolam (one tablet of Eurodin and three tablets of Halcion), by her 37-year-old pharmacist father and then injected with 70 units of insulin (NovoLet 40R). She died several hours after the injection of insulin. Autopsy was carried out 12 h after the death. A glibenclamide level of 103 ng/ml was detected in the serum collected from the heart at autopsy. The serum insulin and C-peptide concentrations were 295 microU/ml and 0.5 ng/ml, respectively. The high level of insulin and the low level of C-peptide indicated that most of the serum insulin was exogenous. The determination of the serum C-peptide concentration was useful to the diagnosis of hypoglycemia caused by exogenous insulin even in the case of co-administration with an endogenous-insulin-releasing agent.