(Lesson 3- Table of Contents) (Next) (Glossary)

General genetic services include clinical genetic evaluations, genetic counseling, laboratory diagnostic services, and services provided through specialty clinics for individuals with specific genetic conditions such as PKU, muscular dystrophy, hemophilia, etc.

GENETIC COUNSELING

Genetic counseling has been defined as a communication process intended to help affected individuals and/or their families to:

comprehend the medical facts (diagnosis, prognosis and management);

understand the contribution of heredity to the disorder and to its recurrence risks in specific relatives;

understand the options available for dealing with this recurrence risk (such as prenatal diagnosis, reproductive alternatives);

choose the course of action most compatible with family goals, values and religious beliefs;

make the best possible adjustment to the condition and its implications1.

The first step in the genetic counseling process is to establish an accurate diagnosis. This involves the collection and review of medical records and family history information. If the patient is a child, most centers also request pregnancy and delivery records and information about the child's psychomotor development. These are usually collected prior to the clinic visit through the use of questionnaires or through a phone interview.

CLINICAL EVALUATION

The clinical evaluation is performed by a clinical geneticist and involves a detailed physical examination. The clinical geneticist will document any unusual physical features (major or minor malformations), developmental delays and neurologic deficits. A number of different measurements to determine such things as the distance between the eyes, the length of the limbs and the upper and lower body segments may be needed. In many instances, it may also be necessary to examine a child's parents and sibs to look for subtle signs of the condition. A clinical photograph may be obtained.

ESTABLISHING A DIAGNOSIS

The physical examination, clinical course, family history and conventional laboratory tests and imaging studies are used to establish a diagnosis. In some cases, the diagnosis is made solely on the basis of the patient's pattern of physical abnormalities, behavioral/developmental findings and family history. Other genetic syndromes are diagnosed using objective laboratory tests such as chromosome studies, DNA tests, neurometabolic screens or enzyme analysis.

Unfortunately, even with the advanced medical technology available today, a specific diagnosis cannot always be established. The cause of birth defects, for instance, can only be determined in approximately 40% of affected children. Of all the infants born with birth defects, 6% have chromosomal abnormalities, 7.5% have single gene disorders, 20% have multifactorial traits, and 4 to 6% have been exposed to known teratogenic agents. The majority of birth defects, however, have no known cause2.

Even when no specific diagnosis is possible, a genetic evaluation can be valuable for families. It may eliminate misconceptions, reduce guilt, or resolve the concerns of other family members.

INFORMATIVE AND SUPPORTIVE COUNSELING

After a diagnosis is made, the natural history of the disorder, the prognosis, and the available management or treatment options are discussed with the patient or his/her parents. Should the condition be heritable, the genetic basis is explained and the family is informed about the recurrence risk in subsequent children and other family members. A follow-up plan is outlined and referrals are made, as appropriate.

If additional tests are ordered, the family will receive information about each test and the time needed for completion. Information is also provided about the syndrome or genetic condition in question and the reasons why the diagnosis is under consideration.

In cases where a diagnosis cannot be established, a family may be asked to return to clinic in six months to two years for a re-evaluation. This is especially common if the patient is a small child or a person who is experiencing a possible deterioration in ability. As physical characteristics and capabilities change over time, the diagnosis may become apparent on a subsequent follow-up evaluation.

Genetic counseling is nondirective. Patients and their families are expected to formulate their own decisions, based on their personal, social and financial circumstances, and their religious convictions.

FOLLOW-UP

Regardless of whether a diagnosis can be established, the specific needs of the individual or family seen in a genetics clinic are assessed. Referrals are made to other medical specialists, social services, special education and support groups when appropriate. Most centers also send a follow-up letter to the patient or the parents summarizing the counseling session and recommendations.

Return clinic visits are an integral part of the genetic counseling process as genetic disorders and birth defects are lifelong. Having a working knowledge of uncommon syndromes, a medical geneticist is able to provide anticipatory care and early diagnosis of secondary complications (e.g., malignant kidney tumor in Beckwith-Wiedemann syndrome, hypothyroidism in Down syndrome, adrenal tumor in neurofibromatosis, etc.). Medical information may change over time, leading to revisions in diagnosis, refinements in treatment, or improved carrier testing or prenatal diagnosis. In addition, follow-up counseling helps to ensure the understanding and retention of information.

THE PROFESSIONALS

In most cases, individuals who are referred for a genetic evaluation will meet with a genetic counselor and a medical geneticist. In a multidisciplinary or specialty clinic, team members may include a social worker, psychologist, nutritionist, occupational, physical and/or speech therapists and other medical specialists. To learn more about the genetics programs and multidisciplinary clinics in your community contact your state genetics coordinator or regional genetics network (Appendix E).

SUMMARY

In medical genetics, the "patient" is not solely the index case or proband, but often includes the parents, sibs and immediate or extended family members. The evaluation process includes family history, a physical examination (with attention to minor malformations), laboratory or imaging studies, and genetic tests (e.g., chromosome analysis, DNA molecular studies, neurometabolic or enzyme analysis), as needed. Genetic counseling is an information sharing process designed to guide the patient/family through an understanding of the diagnosis, prognosis, recurrence risk and personal/social implications surrounding a birth defect or genetic condition.

REFERENCES

1. Robinson A, Linden MG. Clinical genetics handbook: second edition. Cambridge: Blackwell Scientific Publications, Inc.; 1993. 5p.

2. Thompson JS, Thompson MW. Genetics in medicine: fourth edition. Philadelphia: W. B. Saunders Company; 1986.

PRACTICE ACTIVITY 2

1. Genetic counseling is a communication process. List the goals of this process.

Use a T or F to show whether the following statement is true or false.

2. When you refer the parents of a child with a birth defect for a genetic evaluation, they should be reassured that the geneticist will be able to determine the cause of their child's problem.

PRACTICE ACTIVITY 2: ANSWERS

1. The goals of the counseling process are to help affected individuals and/or their families to: (1) comprehend the medical facts; (2) understand the genetics of the disorder and the risk recurrence in specific relatives; (3) understand the options available for dealing with this risk (e.g., prenatal diagnosis, reproductive alternatives); (4) choose the course of action most compatible with their family goals, values, and religious beliefs; and (5) make the best possible adjustment to the condition and its implications. Note, the genetic counseling process is nondirective. Genetic counselors do not, as a rule, tell families what they should do, or what decisions they should make.

2. False It is only possible to determine the cause of a child's birth defects 40% of the time. Sixty percent of children have birth defects/mental retardation with no readily apparent reason.

(Lesson 3- Table of Contents) (Next) (Glossary)