FAQ
What is a gene?
A gene is a segment of DNA that codes for a protein. Humans have approximately 20,000 protein coding genes. Variations in genes, called mutations or variants, can affect how proteins work and influence disease risk.
What is the difference between a germline and somatic mutation?
Germline mutations are present in every cell and can be passed to children. Somatic mutations occur in specific cells during life and cannot be inherited. Cancer involves somatic mutations, while hereditary cancer risk comes from germline mutations.
Who is genetic testing usually offered to?
Clinical genetic testing is commonly offered to people with a strong family history of a genetic condition, unusually early onset disease, or ancestry associated with particular founder variants. Genetic counseling before testing explains the risks, benefits, and limitations. Decisions about testing are made with a health professional. Direct to consumer testing like 23andMe covers only a small fraction of clinically relevant variants.
What is a variant of uncertain significance VUS?
A VUS is a gene change whose effect on health is unknown. On its own it is generally not used to guide medical decisions. Over time, many VUS are reclassified as benign or pathogenic as more data becomes available. Your genetic counselor can help interpret results.
Can genes be changed?
Germline editing of sperm, egg, or embryo DNA for reproduction is prohibited or tightly restricted in many countries. Somatic gene therapies, which modify body cells, are approved for several diseases, and a CRISPR based treatment using edited blood stem cells was approved for sickle cell disease in 2023. Gene editing performed directly inside the body is being tested for conditions such as transthyretin amyloidosis and inherited blindness.
How accurate is genetic testing?
Clinical genetic testing is highly accurate for well characterized genes. However, not all mutations are detected by every test. Full gene sequencing detects most types of disease causing variants, although some, such as large rearrangements or repeat expansions, require additional methods. Newer technologies like whole genome sequencing can detect structural variants previously missed.