Nursing and Genetic Research

Nursing and Genetic Research

Introduction

A genetic test examines the genetic information contained inside a person's cells, called DNA, to determine if that person has or will develop a certain disease or could transmit a disease to a child. Genetic tests also determine whether or not couples are at a higher risk than the general population for having a child affected with a genetic disorder (Wallerstein, 2001).

Purpose

Some families or ethnic groups have a higher incidence of a certain disease than do the population as a whole. For example, individuals of Eastern European, Ashkenazi Jewish descent are at higher risk for carrying genes for rare conditions such as Tay-Sachs disease (a lipid storage disease) that occur much less frequently in populations from other parts of the world. Before having a child, a couple from such a family or ethnic group may want to know if their child would be at risk of having that disease. Genetic testing for this type of purpose is called genetic screening.

During pregnancy, a baby's cells can be studied for certain genetic disorders or chromosomal problems such as Down syndrome (Harris & Washington, 2001). Chromosome testing is most commonly offered when a mother is 35 years or older at the time of delivery. When there is a family medical history of a genetic disease or there are individuals in a family affected with developmental and physical delays, genetic testing may also be offered during pregnancy. Genetic testing during pregnancy is called prenatal diagnosis.

Precautions

Genetic tests are performed on cells derived from blood, bone marrow, amniotic fluid, or tissues. The health care worker collecting the specimen should observe universal precautions for the prevention of transmission of bloodborne pathogens. Because genetic testing is not always accurate and because there are many concerns surrounding insurance and employment discrimination for an individual receiving a genetic test, genetic counseling should always be performed prior to genetic testing. A genetic counselor is an individual with a master's degree in genetic counseling. A medical geneticist is a physician specializing and board certified in genetics (Hakimian, 2000).

A genetic counselor reviews a person's family history and medical records and the reason for the test. The counselor explains the likelihood that the test will detect all possible causes of the disease in question (known as the sensitivity of the test), and the likelihood that the disease will develop if the test is positive (known as the positive predictive value of the test).

Description

Genes and chromosomes

Deoxyribonucleic acid (DNA) is a long molecule made up of two strands of genetic material coiled around each other in a unique double helix structure. Francis Crick and James Watson discovered this structure in 1953. Each strand of DNA consists of a backbone of deoxyribose sugars linked together by phosphate groups. Each sugar is bound (with a covalent bond) to one of four bases, adenine, guanine, thymine or cytosine (Gilbert, 2001). The two strands are held together by hydrogen bonds between the bases. Adenine pairs with thymine and guanine pairs with ...