Karyotype: determination and chromosomal definition

Karyotype: determination and chromosomal definition

#Karyotype #determination #chromosomal #definition

THE karyotype it is a representation, in the form of a photograph, of the set of chromosomes of a cell, divided into pairs and according to their size. This test is performed to detect any chromosomal abnormalities that indicate a genetic disease. It is indicated to reach the diagnosis of mental retardation, congenital malformations and infertility problems in women.

  • Definition of karyotype

  • Karyotype indications

  • Karyotype result

  • Human karyotype

  • Karyotype variations

  • Attention point

Definition of karyotype

The karyotype is the photographic visualization of a set of chromosomes to confirm or rule out any anomalies. It is usually done with normal cells to rule out the possibility of problems such as trisomy 21 or to indicate some aspects of a person’s genetic material, such as sex.

Therefore, it can also be performed on abnormal cells to assess specific cellular dysfunctions, such as cancer or leukemias. The realization of a karyotype requires an evaluation of the cells in the laboratory and a photo of the chromosomes that compose them. Karyotypes are subdivided, as already mentioned, in format and dimension.

Karyotype indications

Chromosomal evaluation is useful for several occasions, including cases of pregnant women with the aim of looking for abnormalities in the fetus. In this case, fetal cells are analyzed, either from amniotic fluid or through the umbilical cord, with access to the placenta. The karyotype in this situation can also be performed by analyzing the umbilical cord blood, after the child is born and in case of suspected chromosomal diseases.

Cases of people with cancer or affected by blood disorders also call for this type of analysis, which can be done by the bone marrow or by the blood glands. Suspicious cases, such as repeated abortions, fertility problems, growth retardation, among others, also call for a karyotype of the affected patient.

Karyotype result

The interpretation of the results of the karyotype is made about two or three weeks after the exam and is based on the number of chromosomes, sex chromosomes present and anomalies that can cause dysfunctions in the structures.

Human karyotype

The human karyotype is composed of 46 chromosomes: 22 identical pairs and a pair of sex chromosomes, 46 XX for women and 46 XY for men.

Karyotype variations

The karyotype can vary in cases of people at risk, but also in cases of trisomy, when the karyotype has 47 XY chromosomes.

Attention point

Results may vary according to the laboratory, depending on the technique used. Therefore, there is no single diagnosis. In any case, it is recommended to consult a doctor to evaluate complementary tests and, eventually, the indicated treatment.

Photo: © Desigofire – Shutterstock.com

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