175 Ethics of Genetic Testing and Medical Disease Diagnostics
175 Ethics of Genetic Testing and Medical Disease Diagnostics
Traditionally, disease is diagnosed when a patient suffers from symptoms or measurable signs. Some diseases are caused (at least in part) by genetic changes to a single gene, some by genetic changes to multiple genes, some by changes to chromosomes or their interactions with the environment. Sickle cell anemia, cystic fibrosis, some versions of hemophilia, phenylketonuria, and Huntington’s disease are caused by mutations to a specific gene or location on a chromosome. Some diseases such as a type 2 diabetes are thought to be influenced by many genes and environmental factors. Some diseases such as trisomy 21 (also known as Down syndrome) are caused when an additional third chromosome is part of someone’s genetic information. Some diseases have a genetic component that increases the risk for a disease, but does not determine with 100% certainty that a person will develop that disease. An example are some mutations in BRCA1 that can increase the risk for breast cancer. Some diseases caused by genetic mutations are life-ending at an early age. Examples are mutations for the gene encoding ADA. ADA is an abbreviation for adenosine deaminase. A mutation causing lack of ADA can cause “severe combined immunodeficiency” (SCID). Persons with non-functional ADA die at a very young age (a few years old) from the lack of a functional immune system, overcome by infections turning lethal against them. Some genetic diseases such as phenylketonuria (PKU) can lead to impairing the cognitive development of a person without intervention. On the other hand, mental impairment can be avoided by giving a diet that avoids or strongly reduces the amount of phenylalanine. Some diseases with genetic components such as diabetes can be improved with improving diets, exercises, patient education, and life style changes. Other genetic diseases such as breast cancer can be monitored with routine testing. Some genetic diseases such as Huntington’s disease are fatal but often start to show the signs and symptoms of illness only later in life, oftentimes when someone is in their 30s or 40s. Some genetic diseases can’t be cured (as of yet but perhaps in the future). Unfortunately, Huntington’s disease is one example. For some genetic diseases, a person can have a recessive disease-causing allele for a gene on one paternal chromosome and a normal allele for the same gene on the chromosome from the other parent. When individuals in this genetic situation have biological children, then there is a chance that one of the children will inherit disease-causing alleles from both parents and suffer from the genetic disease. Sickle cell disease is an example of this type of genetic situation.
In 2005, the National Society of Genetic Counselors (NSGC) defined genetic counseling as “the process of helping people understand and adapt to the medical, psychological and familial implications of genetic contributions to disease” (Waxler,