Library / diagnostic-test-reference
Understanding medical genetics
Audience: patients-public, students-learners ยท Review state: published
Genetics in the clinic
Medical genetics is the branch of medicine that diagnoses and manages conditions caused by changes in genes or chromosomes. It covers inherited disorders present from birth, genetic contributions to common diseases, and the growing use of genomic information in choosing treatments.
Genetic professionals diagnose these conditions through a combination of family history, physical examination, and laboratory testing of DNA, chromosomes or gene products.
How genetic conditions are diagnosed
Diagnosis often starts with the pattern of a family history and clinical findings, then turns to testing: single-gene tests for a suspected condition, panels that read many genes at once, chromosomal analysis for larger structural changes, and increasingly exome or genome sequencing when the answer is elusive.
A clinical geneticist or genetic counselor interprets results in the context of the person and family, because the same variant can mean different things in different families.
What testing can and cannot say
Genetic tests answer different questions: diagnostic testing confirms or rules out a suspected condition, carrier testing shows whether someone could pass a variant to children, predictive testing estimates future risk, and pharmacogenetic testing guides drug choice and dosing.
Results come in three flavors: positive, negative, and variant of uncertain significance, where a change is found but current knowledge cannot say whether it matters. Uncertain results are common and usually resolve over time as databases grow.
Deciding about testing
Genetic information is family information: a result can imply things about relatives who never consented to testing. Counseling before and after testing exists to work through what a result would change, who it affects, and what privacy protections apply.
Testing is a choice, and for predictive tests especially, the right decision depends on what the person would do with the answer.
Limitations
General educational overview, not genetic counseling and not an interpretation of any person's test result. Testing decisions are individual; a clinical geneticist or genetic counselor and current local guidance are the authority.