Cytogenetics

What is Cytogenetics?

Cytogenetics is the science that studies the roles of chromosomes and chromosomes in heredity. In this field, chromosomes are examined numerically and structurally, and their relations with diseases are evaluated. Chromosomes are nucleoprotein structures that are formed as a result of the spiraling and condensation of DNA together with histone proteins and that ensure the inheritance of the genetic material

Prenatal Cytogenetic Analysis                                                                               

• Chromosome analysis from amniotic fluid                
• Chromosome analysis from chorionic (CVS) tissue culture
• Chromosome analysis from cord blood
• Chromosome analysis from pregnancy evacuation material
• Fast Aneuploidy (13,18,21, X, Y) FISH panel
• Fast Aneuploidy (13,18,21) FISH panel

 Postnatal Cytogenetic Analysis 

• Chromosome analysis from peripheral blood
• Chromosome analysis from skin etc. tissues
• Chromosome analysis from bone marrow
• Molecular Karyotyping (Microarray)

What is Chromosome Analysis (Karyotype) Test?

Karyotype test is the examination of chromosomes in terms of number, shape and size. A normal individual has 46 chromosomes in each body cell. The only cell group that contains different numbers of chromosomes in the human body is reproductive, in other words, sperm and egg cells called gamete cells. There are 23 chromosomes in these cells, and when these cells combine with fertilization, they form a normal embryo with 46 chromosomes. If the number of chromosomes is more or less than 46 or is different from normal in terms of shape and size, chromosomal diseases occur.

What is Prenatal Cytogenetic Diagnostic Test?

Prenatal cytogenetic analysis is a diagnostic test used in patients with prenatal diagnosis indication. Prenatal chromosomal analysis can be done by chorionicvillus sampling (CVS) or amniocentesis. Typically, CVS is done during the first trimester of pregnancy for 10-12 weeks of gestation, while amniocentesis is 14-18. It is done in the weeks of gestation. Percutaneous umbilical blood sampling (cordocentesis) is a prenatal diagnostic method generally used in cases where fetal blood is preferred. Cordocentesis is usually done after the 20th week of pregnancy.

Chromosome analysis from the amniocentesis material results in 3 or 4 weeks after the sample reaches the laboratory. Likewise, cytogenetic examinations performed on choryanicvillus samples result in the same period. In addition to karyotype analysis, a prenatal rapid FISH study can be performed to reduce anxiety during this period. The prenatal rapid FISH study is a quick and simple way to detect trisomies 13, 18 or 21 as well as determine the sex chromosome complement of the fetus.

What are the Prenatal Chromosome Analysis Indications?

• Advanced maternal age (35 years and over)
• Increased risk factor in biochemical screening tests (triple double screening tests)
• Abnormal USG findings
• Poor obstetric history (recurrent pregnancy loss)
• Balanced translocation carrier parent
• Child history with chromosomal abnormalities

What should be the material for the test?

When the patient’s indication is determined, the obstetrician takes samples from the patient using 4 different invasive methods in accordance with the week of pregnancy.

• Chorionicvillus (CVS) in sterile transport medium during the 9-11th week of gestation,
• Amniotic fluid in a sterile non-sealed injector during the 16-19th week of pregnancy
• Cord blood in a sterile injector with heparin or in a heparin tube during the 19-22nd week of pregnancy
• Sample of abortion material in sterile transport medium in terminated pregnancy

What is Postnatal Cytogenetic Diagnostic Test?

Peripheral blood, bone marrow and skin, etc. Chromosome studies obtained from tissue samples with short-term or long-term cell culture are called Postnatal Cytogenetic Diagnosis. The samples taken from the patients are analyzed according to their indications and the results are interpreted. The patient is given a report with genetic counseling. The duration of these procedures is usually around 3 weeks.

What are Postnatal (Postpartum) Cytogenetic Diagnostic Tests?

1. Chromosome analysis from peripheral blood culture
2. Chromosome analysis from tissues like skin etc. and cell culture
3. Chromosome analysis from bone marrow

Who Should Be Applied?

In the presence of indications determined by the clinicians of the relevant branches, patients with growth retardation, cases with congenital anomalies, couples with recurrent pregnancy losses and reproductive problems, individuals in the diagnosis and treatment process of hematological diseases, cancer diagnosis and treatment protocols are arranged.

What are the Postnatal Chromosome Analysis Indications?

• Congenital dysmorphic findings
• Developmental Retardation (Mental motor retardation)
• Recurrent Pregnancy Losses
• Pre-IVF screening
• Uncertain (Ambigius) genitalia
• Short Stature
• Sex Development Disorders (Lack of Hair, Not Menstruation, Testicular Development Problem)
• Early Menopause
• Infertility (Azo-oligospremia)
• Family History of Chromosomal Anomalies
• Hematological Diseases / Malignancies

What Should Be the Material for the Test?

• Venous blood in heparinized syringe or heparinized tube
• Bone marrow in heparinized syringe or heparinized tube
• Skin biopsy specimen in transport medium