2 Clinical Trials for Various Conditions
Background: After an allogeneic hematopoietic stem cell transplant (HSCT), the donor genome is found in the recipient s circulation and tissues. Post-HSCT recipients may receive a medication in which the dosing needs to be adjusted based on genetic variation. While genes in donor genome may influence dosing and administration of some agents, the majority of established gene-drug pairs in pharmacogenetics are related to expression of metabolic or transporting enzymes located in recipients tissues, often the liver. Determining which genetic variants influence drug disposition in HSCT recipients is complicated by chimerism in samples that are routinely collected for determining genotype. However, chimerism in tissues is poorly studied in this patient population. Objectives: To determine the most reliable host genomic source for pharmacogenetic testing in participants that have received allogeneic HSCT. Eligibility: People ages 18 years and older who are enrolled on a clinical trial at the NIH Clinical Center under which they will donate or receive an allogeneic HSCT. Design: DNA is collected prior to HSCT and for two years after HSCT. Blood will be collected and skin fibroblast cell lines will be established prior to HSCT to serve as a reference genome. Blood, buccal cells, skin, and hair will be monitored for the development of mixed chimerism via detection of short tandem repeats. Liver biopsies will be collected from participants undergoing hepatic surgery. Pharmacoscan arrays will be conducted to determine which samples are useful for pharmacogenetic testing in participants who receive allogeneic HSCT. A probe drug cocktail will be administered pre- and post-HSCT to determine if transplantation alters the metabolic phenotype of liver enzymes. ...
Cytochrome P450 2D6 (CYP2D6) is an important enzyme in the body for breaking down many medications that are commonly used in children of various ages. The purpose of this proposal is to investigate the relative roles of development and genetic variation in CYP2D6 activity in school-aged children and adolescents with attention deficit and hyperactivity disorder and health controls using the over-the-counter cough suppressant, dextromethorphan or "DM", a standard probe for determining CYP2D6 phenotype. Embedded in the study design are sub-studies to search for by-products of normal body metabolism that reflect differences in enzyme activity, and a pharmacokinetic study to assess the consequences of CYP2D6 genetic variation on the systemic exposure to medications used by this patient population. Ultimately, the goal of the research is to personalize the use of medications in children by selecting the appropriate dose of the correct medication for individual patients.