Clinical Genetics

Clinical genetics is a comprehensive examination in which the medical genetics specialist takes a detailed disease history of the individual suspected of having a genetic disease (which may include the prenatal period, monitoring during pregnancy, birth and thereafter, as well as generations within the family), draws the family tree (pedigree), gathers all tests and imaging studies performed to date along with the specialist evaluations made, and conducts a detailed dysmorphological (visible abnormal physical findings) evaluation together with the patient's routine examination. Using the information and findings obtained, the medical genetics specialist will arrive at a preliminary diagnosis and plan the necessary genetic tests or other tests to support the diagnosis. The medical genetics specialist will manage the patient's care, including diagnosis, treatment options, follow-up, and consultation with other departments. Detailed genetic counseling at the end of all processes is also an important matter. You can contact our laboratory to schedule a genetic examination appointment with our experienced medical genetics specialists.

When Should Genetic Counseling Be Obtained?

• Congenital anomalies, intellectual disabilities, neural tube defects, cleft lip or palate problems, miscarriages with anomalies,
• Prenatal diagnosis due to advanced maternal age (35 years and older) or other reasons,
• Miscarriages (recurrent pregnancy loss),
• Infertility,
• Consanguineous marriages,
• A defined balanced chromosomal translocation carrier status in one spouse,
• Detection of a genetic disease and/or carrier status in oneself or relatives (Down Syndrome, Cystic Fibrosis, Fragile X Syndrome, Rett Syndrome...),
• Cases found positive on newborn screening and premarital routine tests (Phenylketonuria, Thalassemia...)
• Certain diseases that manifest at later ages (such as Huntington's disease),
• Certain cancers (breast, colon, lung, thyroid, etc.),
• Alcohol consumption during pregnancy,
• Treatments taken before or during pregnancy,
• Exposure to radiation during pregnancy (X-ray, CT scan),

Genetic Counseling Process

In the genetic counseling process, a detailed family history should first be taken. Following the patient examination, information should be provided about genetic tests and prenatal diagnosis options if there is an indication. The genetic risks carried by the patients and other family members should be explained. Information and support should be provided about ways to reduce disease risk along with treatment options, if any. Communication should be established with the patient, information should be shared, and support should be given, but the counselor should not be directive at the decision-making stage.

Today, many diseases can be diagnosed as a result of advances in genetic science and laboratory technology. In parallel with the rapid pace of these advances, the need of patients and their families for help and information is also increasing. For this reason, it is recommended that genetic counseling be provided by specialists in the field.

Genetic Counseling & Prenatal Diagnosis

Genetic diseases are generally accompanied by severe physical and mental pathologies. In protecting against these diseases, for which treatment is often limited, genetic counseling and prenatal diagnosis have gained importance. Families with a history of genetic disease should consult genetic diagnosis centers before a new pregnancy.

Prenatal diagnosis is also performed to increase the chances of families carrying a genetic disease risk having healthy children. In this way, action can be taken based on whether the child to be born has the genetic disease or not, and by using PGD methods, it is also possible to have a healthy baby without the need to intervene in the pregnancy.

Which Methods Are Used in Prenatal Diagnosis?

• Non-invasive methods: Most fetal anomalies can be detected through biochemical screening tests (double, triple test) performed on blood samples taken from pregnant women and with the help of ultrasonography (USG).
• Invasive methods: Genetic and biochemical analyses can be performed on material (fetal cells) obtained through amniocentesis, CVS, and cordocentesis.

In Which Situations Is Genetic Testing Recommended During the Prenatal Period?

1. Increased risk on the double and triple test: Detection of high risk on tests performed on blood samples taken from pregnant women is one of the most common indications for prenatal cytogenetic diagnosis.
2. Advanced maternal age: There is a risk of a chromosomally abnormal child in all pregnancies, but in pregnancies after age 35 this risk increases in proportion to age.
3. Pathological ultrasonography findings: The detection of abnormal findings on ultrasonography can be a sign of many genetic diseases. However, the absence of pathological findings on ultrasonography does not indicate that the fetus is 100% healthy either.
4. Balanced chromosomal anomaly carrier status in one spouse: These couples typically consult a physician after recurrent miscarriages or after having a baby with a congenital anomaly. Although carriers of a balanced chromosomal anomaly have a normal external appearance (phenotype), their risk of having a child with a chromosomal anomaly is increased. It is recommended that these cases receive counseling and make use of genetic diagnosis options.
5. Families with a history of a child with a chromosomal anomaly: For couples whose previous children had a chromosomal anomaly, the risk of recurrence in subsequent pregnancies increases at rates that vary depending on the type of anomaly. It is recommended that families consult a genetics specialist to plan their subsequent pregnancies.
6. Detection of hereditary single-gene disorder carrier status in screening tests: Genetic Counseling is recommended for couples identified as carriers (of conditions such as phenylketonuria, sickle cell anemia, cystic fibrosis, or thalassemias) during routine newborn screening, premarital testing, or genetic disease investigations in close relatives.
7. Carrier status for X-linked genetic disorders: In carrier pregnant women, prenatal diagnostic test options directly targeting the disease in question should be evaluated first. However, when this is not possible, indirect analyses using methods such as linkage analysis, karyotyping, or FISH may be recommended (a male fetus carries a high risk of disease).
8. History of multifactorial disease: Prenatal diagnosis is available for certain multifactorial disorders, particularly neural tube defects. If there is a family history of anencephaly and spina bifida, or such history in second-degree relatives, the risk of recurrence in subsequent pregnancies increases (5% for anencephaly, 2% for spina bifida).
9. Recurrent pregnancy loss: Genetic analyses can be performed for families with a history of two or more spontaneous abortions (miscarriages), stillbirths, or babies with anomalies (a poor obstetric history). Based on the test results, treatment planning can be carried out, or prenatal genetic diagnosis/PGD may be recommended.
10. Presence of maternal anxiety: In cases of excessive maternal anxiety, fetal chromosome analysis may be requested without requiring another indication.

Table. Some Single-Gene Disorders Detectable by Prenatal Diagnosis

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