Principles of Care
Claire O. Leonard
The contribution of genetic variation to health and disease has become increasingly clear as a result of our burgeoning understanding of the human genome. Genomic medicine uses an understanding of the individual’s genetic makeup to enhance the quality of medical care, including presymptomatic identification and prevention, determination of susceptibility to disease, selection of treatments, and individual clinical care based on genotype. Most diseases fall somewhere on a continuum from single-gene disorders, disorders with a major gene effect, disorders with complex traits, and those with a predominantly environmental causation. The majority of genetic disorders are multisystemic in their manifestations. Most children with special health care needs have disorders that are caused by mutations in single genes or variations in chromosomes or that are heavily influenced by genetic factors. Genetics can no longer be considered as only the identification of rare syndromes and inborn errors of metabolism. Care for the child with a genetic disorder involves five major activities—suspicion, diagnosis, management, genetic counseling, and advocacy. These activities require a partnership between the pediatrician, one or more specialists or specialty teams, the family, and schools and other support services. No physician can hope to recognize and personally manage all genetic disorders, many of which are quite rare. Treatment for genetic conditions is advancing rapidly, encompassing much more than the supportive care previously available.
Suspicion of a genetic condition must rest with the primary care physician. Situations suggesting a genetic disorder are outlined in Table 172-1. Single organ diseases or birth defects may also be genetic or have a major genetic component. Neuropsychiatric conditions such as autism spectrum disorder are frequently genetic in causation. The American College of Medical Genetics has published a detailed guide to indications for genetic referral.1
Once a genetic condition is suspected, a diagnostic evaluation should be undertaken. Consultation with a geneticist or other specialist is usually valuable to focus the testing. There are no generalized screening tests for genetic disease. As for any clinical diagnosis, a detailed history, family history, and physical examination are the initial steps. The family history or specific biochemical or chromosomal testing may supplement diagnostic information. Mutation analysis (DNA testing) requires a definite clinical or biochemical diagnosis or a suspicion of a specific diagnosis.1 Comparative genomics uses a microarray of DNA segments to evaluate the patient against a known normal panel.2 Although this testing may be useful in some situations, the amount of genetic variability in the population often makes interpretation of results difficult. Exclusion of more easily diagnosed conditions prior to using this screening test is currently recommended. The American College of Medical Genetics and other groups have developed guidelines for diagnostic evaluations under certain clinical circumstances.3-5