Deciphering the human genome in 2001 was followed by an extraordinary development of techniques for genomics studies over the last decade. The impact of these techniques on clinical practice require ongoing reconsideration. Molecular analysis (linkage, microarray CGH, DNA sequencing) have become more and more accessible. Practicing clinicians now have the ability to establish exact diagnoses and more efficient therapeutic strategies than was possible in the past. There are at least 4 domains in which genetic testing has become undoubtedly useful: diagnosis, prediction, prevention, and pharmacogenetics.
Genetic testing for diagnostic purposes in paediatric is indicated in children with signs and symptoms suggestive of genetic disorders, as well as in asymptomatic children with family history of genetic diseases that are amenable to preventive therapies (e.g., familial hypercholesterolemia, urea cycle disorders, haemophilia A, PKU, G6PD deficiency). Genetic testing is not recommended in asymptomatic children without family history of genetic disorders, or in asymptomatic children with family history of genetic disorders that are not amenable to preventive treatments (e.g., Alport syndrome, neurofibromatosis type I, breast cancer, colorectal familial polyposis).
Predictive testing (proactive, prospective) is recommended for individuals at risk for genetic disorders, prior to onset of clinical manifestations. Risk is estimated based on family history of genetic disorders with penetration that is dependent on age (e.g., familial hypercholesterolemia, multiple endocrine neoplasia, Huntington disease).
Susceptibility testing is part of the strategy to diminish an individual’s risk to develop polygenic disease in interaction with environmental exposures (polygenic, multifactorial heredity). This category includes common diseases (e.g., diabetes mellitus, obesity, cancer) as well as congenital malformations (e.g., congenital heart disease, neural tube defects, cleft lip and palate).
Pharmacogenetics testing serves as an aid to identifying gene polymorphisms that influence drug metabolism and action on target cells or organs (pharmacokinetics and pharmacodynamics).