Molecular Diagnosis & Genetic Counseling

Some diseases are caused by environmental factors like exposure to pathogens. Others result from a mix of genetic and environmental causes, while still others stem from genetic factors alone. Genetic counselors assist patients or families with genetic disorders to help them better understand their options. Molecular diagnosis, or the identification of disease through testing DNA and RNA in cells, is important for genetic counseling and a powerful approach to medical diagnosis and treatment in general.

Function

• Molecular diagnostics are tools to diagnose conditions by looking at DNA, RNA and protein molecules from a patient's cells. These techniques have a wide and fast-growing variety of applications in medicine. In oncology, for example, labs can characterize the gene expression profile (a map of genes that are active or turned off) of cells from a tumor biopsy to help categorize the cancer and choose the right option for treatment. To take another example, patients in families with Huntington's disease can have a genetic test performed to determine whether they've inherited the fatal gene from one of their parents.

Significance

• Genetic counseling offers patients the opportunity to know more about a condition that may run in their family, learn whether they may be at risk for the disease, and make choices based on this knowledge. People who are thinking about becoming parents, for example, may want to know whether a disorder they carry could be passed to their children. Genetic counseling and molecular diagnosis can help give people the information they may need to make these decisions.

Types

• Prenatal genetic counselors work with people who want to have children but are concerned about genetic disorders that might run in their family. General or pediatric genetics clinics can use genetic tests to diagnose adults, children or families and provide support for patients with inherited conditions. Psychiatric genetic counselors specialize in working with patients who may have carry genes that could predispose them or their children to certain mental disorders like schizophrenia or autism-spectrum disorders (ASD). Molecular diagnosis is important to all types of genetic counseling, since molecular diagnostics can often help doctors and counselors diagnose specific conditions.

Benefits

• Recently a growing array of genetic tests has made it easier for parents to find out whether they carry genes that could predispose their children to developing a disorder. Cystic fibrosis, for example, is caused by a mutation in a single gene inherited from both parents. Preconception tests screen for the cystic fibrosis gene and various other potentially harmful genetic variants in both parents. Couples who are trying to conceive with the aid of assistive reproductive technology like in-vitro fertilization (IVF) may choose pre-implantation genetic diagnosis to make sure that the embryo is free of specific genetic defects.

Considerations

• For patients who may have inherited genes for disorders like Huntington's disease, the choice to undergo genetic testing can often be a difficult decision. On the one hand, knowing that you don't carry the mutation can free you from the anxiety you might otherwise have felt; on the other hand, knowing that you carry a fatal genetic disease could change the way you live your life. Genetic counselors can help patients make these kinds of decisions. Genetic counseling with the aid of molecular diagnosis is also increasingly important for cancer treatment, where doctors have found ways to distinguish between some cancers that respond better to different types of treatment based on the genetics of the cancer cells. Given the rapid rate at which the cost of gene sequencing is declining, both molecular diagnosis and genetic counseling will probably become even more important in health care in the future.