Genetic analysis or online DNA test?

The difference is not primarily technical but legal and substantive. A mail-order DNA test delivers a report you have to interpret yourself, usually shipped from abroad. A genetic examination in Germany falls under genetic diagnostics law: predictive testing requires a physician, there is mandatory information beforehand and genetic counselling before and after. In practice: a mail-order test gives you a number, a physician-led examination gives you an interpretation of that number against your family history, your laboratory values and your medication.

Buying a test abroad is not prohibited, and nobody commits an offence by ordering one. German genetic diagnostics law, however, governs the conditions under which genetic examinations for medical purposes may be carried out in Germany, and places predictive testing under a physician requirement with mandatory counselling. A provider delivering predictive health statements from abroad operates outside that framework. What that means for you above all: the safeguards the law provides do not apply to such a result. There is no mandatory counselling and no one to interpret the finding.

Yes, and it is often useful. An existing report belongs in the medical history, because it shows what is on your mind and which questions you bring. It does not replace a validated examination: variants from array-based methods are usually confirmed with a different procedure before anything follows from them medically. So expect an abnormal point in the report to be re-examined rather than adopted. The reverse holds too: a normal mail-order test is no reason to skip an indicated examination.

This is the difference least discussed and longest lasting. Genetic data cannot be revoked: you can change a password, you cannot change your germline variants. With mail-order providers, secondary use sits in the terms of service, frequently including transfer to third countries and use for research or commercial purposes, sometimes with the possibility that a dataset transfers on a change of ownership. With a physician-led examination in Germany, medical confidentiality and the restrictions on use under genetic diagnostics law apply. Read the data-sharing section for any provider before you hand over a sample.

Most of all when something could follow from the result. Concretely: with a family clustering of certain cancers or early heart disease, with unclear findings suggesting a hereditary cause, and before treatments whose tolerability is partly genetically determined. Without such a reason, the most likely effect is not a medical gain but a series of variants of uncertain significance that raise questions and answer none. That is not an argument against genetics but one for having an indication. We also say so in the intro call when there is none.