Thanks to the Rapid-FISH method, future parents can find out not only the sex of the child in just a few days, but most of all find out if it is not burdened with genetic defects. When is it advisable to test chromosomal aneuploidy using the Rapid-FISH technique?

NameRapid-FISHstands for fast fluorescent in situ hybridization. It is a molecular method that consists in identifying individual chromosomes by means of genetic probes (DNA, RNA) coupled with a fluorescent dye, complementary to selected sequences of a given chromosome. The most commonly used probes are for chromosomes: 13, 18, 21, X and Y, the numerical aberrations of which are the most common in fetuses. Sounds intricate? Simply put, the Rapid-FISH test allows you to quickly detect sex-related diseases and diagnose the most common numerical chromosomal disorders of the fetus: Patau's syndrome, Edwards' syndrome and Down's syndrome.

Chromosomal abnormalities

When everything is fine and the fetus is developing properly, there should be two sets of homologous chromosomes in the nucleus of each fetus (except for the male X and Y chromosomes). Sometimes, however, it comes to the so-called aneuploidy, i.e. a mutation in which there is one more chromosome - it is a trisomy - or one less chromosome - monosomy. These mutations usually take place on chromosomes 13, 18, 21, X and Y. For example, Down's syndrome is a trisomy of the 21st chromosome, Edwards' - trisomy 18, Patau - trisomy 13. However, mutation of sex chromosomes, i.e. the presence of only one chromosome X, manifests as Turner syndrome.

When Rapid-FISH Testing is indicated

High-risk pregnancies in terms of genetic disorders are said to be when:

  • ultrasound examination, PAPP-A double test and beta hCG - raise doubts;
  • pregnant is more than 35 years old;
  • in the patient's previous pregnancy, the fetus had numerical chromosomal aberration;
  • abnormal nuchal translucency was found in the fetus;
  • the pregnant woman or the child's father has a structural aberration of chromosomes 13, 18, 21, and X.

How the Rapid-FISH examination works

Amniocentesis is recommended if any of the above conditions occurs. It is performed around the 15th week of pregnancy.It is an invasive test, therefore, in order to reduce the risk of complications, it is performed under ultrasound guidance and, of course, with asepsis. The test material is amniotic fluid cells, i.e. amniocytes. They can be assessed after the cultivation time using the classical cytogenetics method (determination of the karyotype), which takes about 2-3 weeks, or the Rapid-FISH method, which gives the result after only 3 days, and sometimes even after 24 hours (it is also correspondingly expensive - approx. 950 PLN).

What is Rapid-FISH

Cell nuclei are isolated from the cells of the amniotic fluid - amniocytes - and then denatured for a short time at an elevated temperature. Then, fluorescent probes are applied to the prepared preparations, and special dyes highlight possible disturbances in the number of individual chromosomes.

The effectiveness of the Rapid-FISH technique

Rapid-FISH is later confirmed in 90% of cases by the result of the classical method. The short waiting time for the result is extremely valuable not only from the point of view of the future parents' peace of mind or the possible future fate of pregnancy. It is very important that many fetal malformations can be treated even before delivery.

About the authorMarta Uler A journalist specializing in he alth, beauty and psychology. She is also a diet therapist by education. Her interests are medicine, herbal medicine, yoga, vegetarian cuisine and cats. I am a mother of two boys - a 10-year-old and a 6-month-old.

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Pregnant examinations