Clinical Genetic Services

What is Genetic Health Care?

By Beth A. Pletcher, MD

Genetic health care essentially crosses all age and specialty lines. Genetic professionals see pediatric, adult and obstetrical patients who have concerns about a genetic condition in themselves, a family member or fetus. Many patients are referred by sub-specialists such as ophthalmologists, neurologists, endocrinologists, neonatologists or cardiologists for evaluation and possible testing. While isolated birth defects may not be considered purely genetic disorders, the prenatal or postnatal diagnosis of a birth defect will often prompt a genetic consultation since isolated birth defects are often genetically determined. Pregnant women may be referred for genetic counseling because of a potential teratogenic exposure, an abnormal screening test such as maternal serum analytes or ultrasound or prior to amniocentesis or chorionic villus sampling.

Who are genetic health professionals?

Within the general practice of genetics there are a number of areas of focus, some of which are highly specialized, and some even have separate areas of board certification. Clinical geneticists typically have experience and skills in dysmorphology and syndromic diagnosis. Biochemical geneticists have special expertise in diagnosis and management of inborn errors of metabolism. Biochemical geneticists who are physicians are often called upon to care for critically ill metabolic patients on an ongoing basis and may or may not function as biochemical laboratory directors as well. Doctorate (PhD) biochemical geneticists primarily run biochemical laboratories. Cytogeneticists may be MDs or PhDs with expertise in the preparation and interpretation of chromosome analyses (karyotypes) and may also function as laboratory directors in this setting. Molecular geneticists may also be MDs or PhDs with expertise in molecular testing and diagnosis. Masters level genetic counselors may work in many clinical settings providing genetic information to individuals and families on a variety of issues. Counselors may obtain detailed family and medical history information to assess genetic risk, explain risks and heritability of genetic conditions to patients, deal with some of the psychosocial aspects of genetic disease and provide support to individuals and their families.

Board certification through the American Board of Medical Genetics is available to MD/DO candidates in: clinical genetics, cytogenetics, biochemical genetics, molecular genetics as well as a newer category biochemical/molecular genetics. PhD candidates can receive certification in all of the above areas except clinical genetics. Board certification for genetic counselors is through the American Board of Genetic Counseling.

What is the purpose of a genetic consultation?

Physicians often turn to genetic professionals for diagnostic information or to confirm a suspected diagnosis. Making a specific genetic diagnosis in a medically complex patient may lead to: 1) improved prognostic information for the patient and family; 2) clarification of the mode of inheritance with correct risk assessment for the patient or other family members; 3) preventative or anticipatory medical care that may improve the overall health of the patients; and finally 4) provision of disease specific support group and medical information to the family.

The complexity of genetic testing

Genetic testing can be quite costly and test results themselves are often difficult to interpret. Therefore, as part of the genetic evaluation, a rational plan about which tests are indicated is a first priority. Furthermore, clinicians need to be aware of the accuracy or detection rate of each test they may order and the need to obtain informed consent from individuals before proceeding with this type of testing. This is particularly true of disease specific molecular tests, which are quite complex and may require participation from a number of family members. Cytogenetic testing is more routine with a fairly high yield in selected populations. Fragile X testing for males with mental retardation has become a relatively routine part of their evaluation. Carrier screening tests for a variety of disorders is being offered routinely to couples based upon their ethnic background or family history, in anticipation of a pregnancy or during a pregnancy. Biochemical testing is usually considered when an individual presents with very suggestive signs and symptoms such as developmental regression, mental status changes, cataracts, hepatosplenomegaly, recurrent vomiting of unknown etiology or metabolic acidosis. Genetic professionals have resources available to them that can be shared with other health care providers who wish to access genetic testing information and can serve as a resource when molecular testing for a relatively rare disorder is under consideration. As part of the genetic evaluation, routine blood studies such as CBCs and electrolytes may also be in order. Radiographic studies including CT and MRI may also help in making a specific genetic diagnosis.