Diagnostic Genetics

What is diagnostic genetics?

Diagnostic genetics is a branch of medical science that focuses on identifying genetic abnormalities that may cause or increase the risk of diseases. It involves analyzing a person's DNA, chromosomes, and proteins to detect mutations or variations associated with inherited disorders. By pinpointing these genetic changes, healthcare providers can diagnose conditions more accurately, guide treatment decisions, and provide individuals with critical information about their health. This field plays a vital role in understanding complex genetic conditions such as cystic fibrosis, muscular dystrophy, and certain cancers.

How are genetic tests performed?

Genetic tests can be performed using various methods depending on the type of information being sought. Most commonly, genetic tests are done through:

• Blood tests: A blood sample is taken and analyzed for genetic mutations or chromosomal changes.
• Saliva samples: Less invasive than blood tests, saliva collection is often used for simpler genetic tests.
• Tissue samples: Sometimes, a skin biopsy or other tissue is required to study specific genetic issues.
• Prenatal testing: In cases where genetic conditions are suspected in an unborn baby, doctors may use amniocentesis or chorionic villus sampling (CVS) to collect fetal DNA. Once collected, the samples are sent to a lab where DNA is extracted and analyzed for specific genetic markers.

What types of genetic disorders can be diagnosed?

A wide range of genetic disorders can be diagnosed through genetic testing, including:

• Single-gene disorders: These are caused by mutations in one specific gene, such as cystic fibrosis, sickle cell anemia, or Huntington's disease.
• Chromosomal disorders: Conditions like Down syndrome or Turner syndrome occur due to changes in chromosome number or structure.
• Multifactorial disorders: These involve multiple genes and environmental factors, such as heart disease, diabetes, and certain cancers.
• Inherited cancer syndromes: BRCA1/2 mutations linked to breast and ovarian cancer, or Lynch syndrome, which increases the risk of colon cancer, are examples of conditions that can be diagnosed through genetic testing.

Who should consider genetic testing?

Genetic testing can be beneficial for various individuals, including:

• People with a family history of genetic disorders: If multiple relatives have been diagnosed with conditions like cancer, heart disease, or a genetic disorder, testing may help determine inherited risks.
• Expecting parents: Those concerned about passing on a genetic condition to their children may opt for carrier screening or prenatal testing.
• Individuals with symptoms of a genetic disorder: Testing can confirm the presence of a genetic condition and help guide treatment.
• People from certain ethnic groups: Some populations have a higher incidence of genetic diseases, like Tay-Sachs disease in Ashkenazi Jews, prompting targeted screening.
• Individuals seeking personalized medical treatment: Genetic testing can inform the best medications or therapies, especially in fields like oncology and pharmacology.

What is the difference between diagnostic and predictive genetic testing?

• Diagnostic genetic testing is used to identify whether a person currently has a genetic condition. It's typically performed when there are symptoms or a strong suspicion of a disorder, such as in cases of muscular dystrophy or cancer.

Predictive genetic testing, on the other hand, assesses whether an individual is at risk of developing a genetic condition in the future. This is common for late-onset conditions like Huntington’s disease or certain cancers. While predictive testing can't guarantee whether the disease will occur, it can inform individuals of their genetic predisposition and help them make proactive health decisions.