Guide
Genetic tests
Explains in plain language what genetic tests, from karyotyping to genome sequencing, are used for, how to read the results and how your genetic data is protected in Türkiye.
Which test is used for what?
The doctor chooses the test based on the suspected condition; if the diagnosis is unclear, a broader test may be ordered, and if it is clear, a narrower one.
A screening test is not the same as a diagnostic test
A screening test estimates whether the risk of a disease is high or low. It is done in people who have no symptoms. A positive screening result does not mean the person has the disease. A diagnostic test, on the other hand, confirms or rules out the disease in a person who has symptoms. A screening result is often confirmed with a diagnostic test.
Source: MedlinePlus Genetics – Screening vs. diagnostic tests · MedlinePlus Genetics – What are the uses of genetic testing?
Karyotype (chromosome analysis)
A karyotype is an image of the chromosomes in a cell, arranged in order. It shows whether the number or structure of the chromosomes is altered. For example, an extra chromosome or a piece that has moved to another place may be seen. It is used for chromosome conditions that can be recognized, such as Down syndrome. It may also be ordered when there is a chromosome rearrangement in the family or a history of several miscarriages.
Source: NHGRI – Karyotype (Talking Glossary) · MedlinePlus Genetics – What are the different types of genetic tests? · Miller DT ve ark. Am J Hum Genet 2010 – Kromozomal mikroarray uzlaşı bildirisi (PubMed 20466091)
Chromosomal microarray
A microarray finds missing or extra pieces of chromosomes that are too small to be seen under the microscope. It is one of the first tests often ordered for unexplained developmental delay, autism or multiple congenital problems. In these situations it leads to a diagnosis more often than a karyotype. But it cannot see cases where pieces have only changed places. It can also miss changes that are present in only a small share of cells.
Source: Miller DT ve ark. Am J Hum Genet 2010 – Kromozomal mikroarray uzlaşı bildirisi (PubMed 20466091) · MedlinePlus Genetics – What are the different types of genetic tests?
Single-gene test and gene panel
A single-gene test looks at changes in one gene. It is used to confirm the diagnosis when a specific condition is suspected. A gene panel looks at many genes at the same time. It is preferred when the symptoms fit several conditions or when many different genes can cause the condition. If a change is already known in the family, relatives can have a test that looks only for that change.
Source: MedlinePlus Genetics – What are the different types of genetic tests?
Exome and genome sequencing
The exome is the part of the genes that makes proteins. It makes up about 1 percent of the whole genome. Most known disease-causing changes are in this part. Genome sequencing reads all of the DNA. These tests are often ordered when narrower tests have not found a diagnosis or when the cause is unclear. Many changes are found, but the meaning of all of them is not known.
Source: MedlinePlus Genetics – Whole exome and whole genome sequencing · MedlinePlus Genetics – What are the different types of genetic tests?
Genetic counseling before and after the test
Genetic counseling is a conversation to discuss what you might learn before the test and what the result means after it.
What happens in counseling?
The genetics specialist asks about your medical history and your family history. They may examine you and suggest a suitable test. If a diagnosis is made, they explain how the condition is inherited and the chance of it passing to the next generations. The specialist does not make decisions for you. They respect your beliefs and your feelings. For a general description of counseling, you can also see the “Newly diagnosed: first steps” guide.
Source: MedlinePlus Genetics – What happens during a genetic consultation? · NHS – Genetic and genomic testing
Information and consent
Before the test, its purpose, its limits and the possible results are explained to you. In Türkiye, the center obtains your explicit consent after giving this information. Only then does it go ahead. For children who cannot make their own decision, consent is given by the mother, the father or the legal representative. Consent is not a contract. You can withdraw from the test even after the sample has been taken.
Source: Tıbbi Laboratuvar Hizmetleri ve İleri Teknoloji Tıbbi Laboratuvar Uygulamaları Hakkında Yönetmelik, md. 22/1-ö (RG 24.10.2025/33057) · MedlinePlus Genetics – What is informed consent?
How is the sample taken, and when will the result come?
The test is usually done on a blood or saliva sample. Sometimes cells are collected from the inside of the cheek with a cotton swab. The sample is sent to a genetics laboratory. You will be told when to expect the result. Depending on the type of test, this can take weeks and sometimes months. When the result arrives, another counseling appointment may be held.
Source: NHS – Genetic and genomic testing · MedlinePlus Genetics – How is genetic testing done?
Understanding the results
Genetic test results are not always clear-cut; the result needs to be interpreted together with the family history and the symptoms.
A positive result
A positive result means the laboratory found a change in the gene or chromosome it examined. This may confirm a diagnosis or show that the person is a carrier. But it often cannot tell how severe the condition will be. Family members may also be affected by this result. Although very rare, a false positive result is possible.
Source: MedlinePlus Genetics – What do the results of genetic tests mean? · MedlinePlus Genetics – Risks and limitations of genetic testing
A negative result
A negative result means that no change known to affect health was found in the part that was examined. But this does not always mean there is no genetic cause. Many tests cannot see every change that can cause a condition. So another test, or testing again in the future, may be needed. You can discuss what to do next with your doctor.
Source: MedlinePlus Genetics – What do the results of genetic tests mean? · NHS – Genetic and genomic testing
Variant of uncertain significance (VUS)
Sometimes it is not known whether the change that was found causes disease. This is called a variant of uncertain significance, written VUS for short. This result neither confirms nor rules out a diagnosis. Testing family members who are and are not affected sometimes clarifies the result. As science advances, the meaning of this change may be better understood in the future.
Source: MedlinePlus Genetics – What do the results of genetic tests mean? · NHS – Genetic and genomic testing
Secondary (unexpected) findings
Exome and genome tests may also find a change that has nothing to do with the condition being investigated. This is called a secondary finding. For example, it may show a risk of certain cancers or heart diseases later in life. This information can be useful for early prevention, but it can also cause worry. In some countries, people can choose not to learn about these findings. You can ask your doctor about this before the test.
Source: MedlinePlus Genetics – Secondary findings · MedlinePlus Genetics – Whole exome and whole genome sequencing
Reanalysis
A test that does not lead to a diagnosis today can be re-examined years later with new knowledge. According to one review, a new diagnosis was made in about one in ten of the reanalyzed cases. Most of the new diagnoses came from newly published scientific knowledge. You can ask your doctor whether your exome or genome data can be re-examined in the future.
Source: Dai P ve ark. Genet Med 2022 – Dizileme verisinin yeniden analizi, sistematik derleme (PubMed 35550369) · NHS – Genetic and genomic testing
What the result means for the family
Because family members share some of their genes, one person’s result may also concern their relatives.
Testing parents and relatives
When a change is found, the doctor may suggest testing the mother and father or other relatives as well. This can help the result be better understood. Relatives can also find out whether they carry the same change. You can discuss who may need testing during genetic counseling. Whether or not to be tested is each adult’s own decision.
Source: MedlinePlus Genetics – What do the results of genetic tests mean? · NHS – Genetic and genomic testing · MedlinePlus Genetics – What happens during a genetic consultation?
Carrier testing
A carrier is a person who has one copy of a disease-causing change but is usually not ill. Carrier testing may be offered to people who have a genetic condition in their family. If prospective parents are tested together, it gives information about the chance of the condition in their children. State premarital screening programs are described in the “Newly diagnosed: first steps” guide.
Source: MedlinePlus Genetics – What are the uses of genetic testing?
Unexpected information and feelings
Results can bring up anger, anxiety, sadness or guilt. These feelings are very common. A result can also cause tension within the family. A test can sometimes reveal previously unknown information about family relationships. For example, that someone was adopted. You can discuss this possibility with your counselor before the test.
Source: MedlinePlus Genetics – Risks and limitations of genetic testing · NHS – Genetic and genomic testing
The privacy of your genetic data
In Türkiye, genetic data is special category personal data protected by law.
Genetic data is special category personal data
Under the Kişisel Verilerin Korunması Kanunu (KVKK, Personal Data Protection Law), health and genetic data are special category personal data. As a rule, processing this data is prohibited. However, it may be processed in the situations listed in the law. For example, if you have given explicit consent or if it is necessary for diagnosis and treatment. This is done by people bound by a duty of confidentiality or by authorized institutions. In addition, extra security measures must be taken.
Source: 6698 sayılı Kişisel Verilerin Korunması Kanunu, md. 6 (mevzuat.gov.tr)
Who can your results be shared with?
The genetics center cannot share your result with anyone else without your explicit consent. This rule is written in the regulation. Records are also kept in line with the data protection law. The system in which the records are kept is protected against outside access. You can ask before the test who the result will be given to.
Your rights over your data
You can apply to the institution that holds your data. You can ask what your data is used for. You can also find out who it has been shared with. If it is wrong, you can ask for it to be corrected. If the conditions in the law are met, you can also ask for it to be deleted. The application is made in writing. The institution must respond within thirty days at the latest. As a rule, no fee is charged for this.
Source: 6698 sayılı Kişisel Verilerin Korunması Kanunu, md. 11 ve md. 13 (mevzuat.gov.tr)
Where and how is testing done in Türkiye?
Genetic diagnostic services are provided at centers authorized by the Sağlık Bakanlığı (Ministry of Health), on a doctor’s request.
Genetic disease diagnosis and evaluation centers
In these centers, a genetics laboratory and an outpatient clinic work together. This means that both testing and genetic counseling are provided. Centers are opened with a license or permit issued by the Ministry of Health. Medical genetics or pediatric genetics specialists work at the center. This service cannot be provided without a permit.
When does SGK pay?
Whether SGK (Social Security Institution) pays for genetic tests depends on the rules in the Sağlık Uygulama Tebliği (SUT, Health Implementation Communiqué). The doctor must write on the request form why the test is needed. Whether the test is necessary for diagnosis and whether it changes treatment are also stated. Molecular genetic tests that a person has done at their own request, without a medical or legal need, are not paid for by SGK. You can ask your hospital about your own situation.
Source: SGK Sağlık Uygulama Tebliği (SUT), md. 2.4.4.G-1 ve 2.4.4.G-2 (mevzuat.gov.tr)
Some prohibitions in the regulation
At these centers, tests for genetic diseases or predispositions may only be done for a medical need or for medical research. In genetic diagnosis during pregnancy or in IVF, testing may not be done solely to find out the sex without a medical reason. A center that breaks this rule has its license revoked. Testing during pregnancy is covered separately in the “Planning a pregnancy” guide.
Direct-to-consumer tests
Genetic tests bought online or without a doctor do not replace the diagnostic tests that a doctor orders.
What can these tests not tell you?
Tests of this kind often look at only a few changes in a gene, not all of them. They cannot tell you for certain whether you will develop a disease. Before results are used for medical decisions, they need to be confirmed by a test ordered by a doctor. If your result worries you, you can talk to a genetics specialist.
Source: MedlinePlus Genetics – What should I know before direct-to-consumer genetic testing? · MedlinePlus Genetics – What are the different types of genetic tests? · MedlinePlus Genetics – How is genetic testing done?
Questions to ask about privacy
Your DNA is unique to you, but you share part of it with your relatives. Before buying, you can read the company’s privacy policy carefully. Check how the data is protected and whether it is shared with or sold to others. Also ask whether you can delete your data. Find out what will happen to your sample if the company closes or is sold. Sending a sample abroad means your data goes abroad too.
Source: MedlinePlus Genetics – What should I know before direct-to-consumer genetic testing? · 6698 sayılı Kişisel Verilerin Korunması Kanunu, md. 9 (mevzuat.gov.tr)
The rule in Türkiye
In Türkiye, authorized genetics centers cannot perform disease or predisposition tests other than for a medical need or medical research. SGK also does not pay for tests that a person has done at their own request. So if you are thinking about a genetic test, it is helpful to talk to your doctor first. That way the right test can be done, together with counseling.
Source: Tıbbi Laboratuvar Hizmetleri ve İleri Teknoloji Tıbbi Laboratuvar Uygulamaları Hakkında Yönetmelik, md. 22/1-m (RG 24.10.2025/33057) · SGK Sağlık Uygulama Tebliği (SUT), md. 2.4.4.G-1 ve 2.4.4.G-2 (mevzuat.gov.tr)
Questions to ask your doctor
You can print this list, take it to your appointment and note the answers below each question.
- What question is this test trying to answer? Why did you choose this test?
- Could the test result change my child’s treatment or follow-up?
- If the result is negative or shows a variant of uncertain significance (VUS), what will the next step be?
- Do the mother and father or other relatives need to be tested as well?
- Are secondary findings reported in exome or genome testing? Can I choose not to learn about them?
- When will the result be ready? Who will explain it, and how?
- Is the test covered by SGK? Is there anything we have to pay?
- How long will my data and sample be kept? Will they be used in research?
- Can this data be re-examined in the future? What do we need to do for that?
This guide is for information only and does not replace medical or legal advice. If you notice missing or incorrect information, please write to us.