A Synopsis of the "Influence of Epigenetics, Genetics, and Immunology" Session Part A at the 35th Annual Society of Toxicologic Pathology Symposium.

The overarching theme of the 2016 Society of Toxicology Pathology's Annual Symposium was "The Basis and Relevance of Variation in Toxicologic Responses." Session 4 focused on genetic variation as a potential source for variability in toxicologic responses within nonclinical toxicity studies and further explored how knowledge of genetic traits might enable targeted prospective and retrospective studies in drug development and human health risk assessment. In this session, the influence of both genetic sequence variation and epigenetic modifications on toxicologic responses and their implications for understanding risk were explored. In this overview, the presentations in this session will be summarized, with a goal of exploring the ramifications of genetic and epigenetic variability within and across species for toxicity studies and disseminating information regarding novel tools to harness this variability to advance understanding of toxicologic responses across populations.

Identification of MHC Haplotypes Associated with Drug-induced Hypersensitivity Reactions in Cynomolgus Monkeys.

Drug-induced hypersensitivity reactions can significantly impact drug development and use. Studies to understand risk factors for drug-induced hypersensitivity reactions have identified genetic association with specific human leukocyte antigen (HLA) alleles. Interestingly, drug-induced hypersensitivity reactions can occur in nonhuman primates; however, association between drug-induced hypersensitivity reactions and major histocompatibility complex (MHC) alleles has not been described. In this study, tissue samples were collected from 62 cynomolgus monkeys from preclinical studies in which 9 animals had evidence of drug-induced hypersensitivity reactions. Microsatellite analysis was used to determine MHC haplotypes for each animal. A total of 7 haplotypes and recombinant MHC haplotypes were observed, with distribution frequency comparable to known MHC I allele frequency in cynomolgus monkeys. Genetic association analysis identified alleles from the M3 haplotype of the MHC I B region (B*011:01, B*075:01, B*079:01, B*070:02, B*098:05, and B*165:01) to be significantly associated (χ2 test for trend, p < 0.05) with occurrence of drug-induced hypersensitivity reactions. Sequence similarity from alignment of alleles in the M3 haplotype B region and HLA alleles associated with drug-induced hypersensitivity reactions in humans was 86% to 93%. These data demonstrate that MHC alleles in cynomolgus monkeys are associated with drug-induced hypersensitivity reactions, similar to HLA alleles in humans.

Reproductive performance and early postnatal development in interleukin (IL)-13-deficient mice.

OBJECTIVE: The purpose of this study was to assess the effect of interleukin (IL)-13 deficiency on fertility and reproductive performance of adult mice and on morphological and behavioral development of the offspring. METHODS: Wild-type and homozygous IL-13-deficient (KO) mice were grouped by genotype, and male and female mice were mated within each group. Adult (F(0) ) mice were evaluated for reproductive performance, and development was assessed in F(1) fetuses on gestation day 18, and in F(1) pups to postnatal day 35. RESULTS: In F(0) males, there were no differences in the number of males that mated or impregnated females, or in total sperm count or sperm motility, between the wild-type and KO groups. In F(0) females, there were no observed genotype-related differences in fertility, length of gestation, number of viable fetuses per litter, or viability of offspring. There were no differences in embryo-fetal development (external/palate, skeletal, visceral) of the F(1) fetuses between genotypes. Similarly, IL-13 deficiency had no impact on any postnatal parameters assessed including reflex, sexual maturation, learning, and memory. CONCLUSIONS: IL-13 deficiency had no observed effect on reproductive performance or morphological and behavioral development in mice.

Utilizing genomic DNA purified from clotted blood samples for single nucleotide polymorphism genotyping.

CONTEXT: Linking single nucleotide polymorphisms to disease etiology is expected to result in a substantial increase in the number of genetic tests available and performed at clinical laboratories. Whole blood serves as the most common DNA source for these tests. Because the number of blood samples rises with the number of genetic tests performed, alternative DNA sources will become important. One such alternative source is clotted blood, a by-product of serum extraction. Efficiently using an already procured blood sample would limit the overall number of samples processed by clinical laboratories. OBJECTIVE: To determine if DNA purified from clotted blood can be effectively used for single nucleotide polymorphism genotyping. DESIGN: DNA was purified from the clotted blood of 15 donors. Single nucleotide polymorphism genotyping for the methylenetetrahydrofolate reductase and factor V Leiden mutations was performed with each DNA sample by 2 independent methods. RESULTS: High-quality DNA was obtained from each of the 15 individual clotted blood samples as demonstrated by UV spectrophotometric analysis, gel electrophoresis, and polymerase chain reaction amplification. The DNA was used successfully to obtain genotype data from both the methylenetetrahydrofolate reductase and factor V single nucleotide polymorphism assays for all samples tested. CONCLUSIONS: Clotted blood is a clinically abundant sample type that can be used as a source of high-quality DNA for single nucleotide polymorphism genotyping.