Pharmacogenetics

Apert syndrome with glucose-6-phosphate dehydrogenase deficiency: a case report

Apert syndrome is characterized by midface hypoplasia, syndactyly of the hands and feet, proptosis of eyes, steep and flat frontal bones, and premature union of cranial sutures. Maxillary hypoplasia, deep palatal vault, anterior open bite, crowding of the dental arch, severely delayed tooth eruption, and dental malocclusion are the main oral manifestations of this syndrome. In this report, a case of Apert syndrome with glucose-6-phosphate dehydrogenase (G(6)PD) deficiency is presented. The patient, a 4-year-old male and the fourth child of healthy parents, was admitted to our department because of delayed tooth eruption. He had all the cardinal symptoms of the Apert syndrome. Clinical examination revealed that primary centrals, canines and first molars erupted; however, primary second molars and laterals had not erupted. The patient had no dental caries. Preventive treatments were applied, and subsequently, the patient was taken to long-term follow up.

Pharmacogenetic tactics and strategies: implications for paediatrics

Genetic diversity exerts profound effects on variation in human drug response in adults, but comparatively little research that specifically relates to genetically abnormal responses in infancy and childhood has been reported. Specific genetic changes in human enzymes, receptors and other proteins that are implicated in drug response and their associated phenotypic correlates provide needed data for construction of profiles individualised to predict susceptibility to adverse drug reactions. If therapy adheres to such guidelines, failure to respond to drug therapy and drug toxicity among genetically susceptible persons can be greatly minimised or averted.

Genetic and environmental factors causing variation in drug response

Large pharmacokinetic variations, ranging in magnitude from 4- to 40-fold, often exist among the members of a given population. These variations create differences in risk of cancer by accelerating metabolic activation of certain environmental carcinogens in some subjects, while retarding such rates in other subjects. To identify specific genetic and environmental causes of large interindividual variations in these rates, several methods have been developed to probe hepatic cytochrome P-450 isozymes responsible for xenobiotic activation. In patients, dynamic interactions occur between genetic and environmental factors causing large interindividual variations in xenobiotic metabolism. Even the same patient can change dosage requirements with time and condition. Appropriate marker drugs can sensitively indicate pharmacokinetic capacity at any given time in a patient or normal volunteer. With respect to genetic factors, twin and family studies are the traditional methods used to test pharmacogenetic hypotheses. Representative examples are cited to illustrate how twin and family studies serve this purpose. Monogenic control of large interindividual variations in the activity of approx. 12 P-450 isozymes has been described. Individual metabolic pathways need to be investigated for drugs biotransformed by multiple pathways. Since many hepatic P-450 isozymes are extremely sensitive to perturbation by numerous environmental alterations, the critical role of selection criteria is stressed to assure that all subjects of twin and family studies are under as uniform environmental conditions as possible. Otherwise, the operation of genetic factors may be concealed or misinterpreted in studies that do not use gene cloning or protein sequence.