Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (419 page)

If a prenatal screening or test is abnormal, the genetic counselor evaluates the risk of an affected pregnancy, educates the patient about these risks, and informs the patient of their options. A person may also undergo genetic counseling after the birth of a child with a genetic condition. In these instances, the genetic counselor explains the condition to the patient along with recurrence risks in future children. In cases of a positive family history for a condition, the genetic counselor can evaluate risks and recurrence and explain details about the condition.

INFORMED CONSENT

Informed consent is the process by which a health care provider discloses appropriate information to a competent patient so that the patient may make a voluntary choice to accept or refuse treatment, and thus be an informed participant in health care decisions. In this way, an individual receives information about their health condition and treatment options, and he/she is able to decide what health care treatment they want to receive and give consent to actually receive it.

“
Request for Release of Medical Information
” is a written consent document for the requested release of a person’s genetic information or the release of medical records containing such information. Such a written consent form shall state the purpose for which the information is being requested and shall be distinguished from written consent for the release of any other medical information.

“
Genetic information
” is any written or recorded individually identifiable result of a genetic test. In many instances, a laboratory receiving a request to conduct a genetic test from a facility, a physician, or a health care provider may conduct the requested test only when the request is accompanied by a signed statement of the medical practitioner ordering the test warranting that the appropriate prior written consent has been obtained from the patient.

FACTORS TO CONSIDER WHEN ORDERING GENETIC TESTS

  1.  
Family history—
is an important source of information about risks of genetic disease. Factors to consider are the mode of inheritance of the diseases, ethnicity, possibility of a new mutation, the presence of inherited susceptibility, consanguinity of the parents, adoption, the use of artificial insemination by donor sperm, and multiple sexual partners.

  2.  
Risk factors
—the age and past or present exposure to an environment that is more likely to result in disease in those with genetic predispositions.

  3.  
Availability of treatment or preventive therapy.

  4.  
Possibility of modification of patient behavior—
preventive behavior

  5.  
The test needs to be beneficial for the patient
, - if the test result could inflict “psychological harm,” pre- and posttesting, genetic counseling must be available, (such as in the case of Huntington disease). At-risk individuals may want to make informed reproductive and career decisions at a time when a disease is not yet clinically detectable.

GENETIC NONDISCRIMINATION LEGISLATURE

Most European countries have since 1990 enacted genetic nondiscrimination legislation for life or health insurance to address concerns about potential misuse of genetic information. There is no specific genetic legislation at EU level except data protection and discrimination provisions related to handling and using genetic data: “genetic data pertaining health are ‘sensitive data’ under EU data protection directive and is thus to be treated confidentially.”

The U.S. 2008 Genetic Nondiscrimination Act: Title I: Genetic nondiscrimination in health insurance (Sec. 101): amends the Employee Retirement Income Security Act of 1974 (ERISA), the Public Health Service Act (PHSA), and the Internal Revenue Code to prohibit a group health plan from adjusting premium or contribution amounts for a group on the basis of genetic information.

U.S. Genetic Nondiscrimination Act Title II:

   Prohibits employment discrimination on the basis of genetic information (Sec. 202). Prohibits, as an unlawful employment practice, an employer, employment agency, labor organization, or joint labor–management committee from limiting, segregating, or classifying employees, individuals, or members because of genetic information in any way that would deprive or tend to deprive such individuals of employment opportunities or otherwise adversely affect their status as employees.

   Prohibits, as an unlawful employment practice, an employer, employment agency, labor organization, or joint labor-management committee from requesting, requiring, or purchasing an employee’s genetic information, except for certain purposes, which include where (1) such information is requested or required to comply with certification requirements of family and medical leave laws; (2) the information involved is to be used for genetic monitoring of the biologic effects of toxic substances in the workplace; and (3) the employer conducts DNA analysis for law enforcement purposes as a forensic laboratory or for purposes of identification of human remains.

MOLECULAR TESTS USED FOR DETECTION AND MONITORING INFECTIOUS DISEASES

The sample should be collected before starting treatment.

   Qualitative: Detection of the presence of viral particles or confirmation of positive viral antibody test; reported as “positive” or “negative”; highly sensitive low limit of detection.

   Quantitative: Measurement of the amount of virus to monitor the effectiveness of a treatment (copies/mL, IU/mL, log).

   Genotyping: Determination of the viral type or subtype when considering antiviral therapy. Genotype testing is available and is useful in treatment planning and for determining length and possible response to treatment. Genotype testing should be done as part of the patient’s initial evaluation once infection has been confirmed. It may aid in identifying the source of infection.

   High sensitivity of molecular assays allows early detection of infection when other markers are negative and detection of infection in immunocompromised patients (antibodies negative). In additional to monitoring the patient’s response to therapy, the molecular test will be negative before antibodies are negative.

   Molecular tests allow for high specificity of the tests by using conserved regions of genomic sequence of organisms’ species and subspecies.

GENETIC DISEASES

   
DISORDERS OF THE IMMUNE SYSTEM