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Human Reproduction

Human
Reproduction

Genetic diagnosis techniques applicable to patients and embryos


Increasingly, genetics is becoming into an essential diagnosis means within modern medicine, even aiming towards a therapeutic use in current researching.

The incorporation of such techniques into the reproductive medicine is a fact. Therefore, CELAGEM puts at your disposal genetic diagnosis techniques applicable to patients, gametes, embryos and/or fetuses. There are various techniques used in genetic diagnosis within reproductive medicine, among them:

1. Detection of infectious microorganisms in couples

Currently, we know about the presence of several microorganisms responsible for inflammatory processes in both female and male reproductive systems, such as Chlamydia Trachomatis, Ureaplasma Urelyticum, Mycoplasma Genitalium and Neisseria Gonorreae, leading specialists to take them into account when making a diagnosis of possible infertility causes in couples. Therefore, CELAGEM offers a Multiplex called couple’s Fertiplex, which jointly identifies these microorganisms in a single sample of semen or cervical swab. In recent studies performed by us in couples that attended to four fertility units, we found a 16.5% of incidence and prevalence of infections caused by these microorganisms – 14.25%, 2.25% and 1% for Ureoplasma Urealiticum, Chlamydia Trachomatis and Mycoplasma Genitalium, respectively. In the same way, chronic viral disease incidence, such as Hepatitis C, Hepatitis B and HIV, is very common in Latin American medical reality, so that, CELAGEM offers the analysis, quantification and sperm-washing services for all those couples infected by some of these viruses, and thus ensuring to their offspring to be free of those infections.

2. Karyotype in peripheral blood, amniotic fluid, and abortion remains

It is a cytogenetic test performed to individuals to identify chromosomal abnormalities caused by deformities or disease. Results of a karyotype may indicate genetic changes related to a disease. As the test mentioned above, it is performed to the fetus to prenatally diagnose chromosomal abnormalities by karyotyping. In the case of amniotic fluid, the sample is obtained by means of an echo-guided puncture between the week 14 and week 18 of pregnancy. At least, three primary cultures are analyzed up to completing twenty cells in metaphase to identify numerical and structural abnormalities in chromosomes. It is also the same test performed to the fetus in cases of recurrent abortions to seek chromosomal abnormalities by the karyotyping. The sample is obtained by a tissue after curettage. It also may be obtained by a skin sample when is a grown fetus aborted.

3. Fluorescence in situ hybridization (FISH) in human sperm

As above, a fluorescence in situ hybridization (FISH) in human sperm is performed. In such test, constitutional numerical abnormalities of chromosomes are determined. The test is performed in de-condensed nuclei for chromosomes 13, 18, 21, X and Y. Results from infertile individuals with normal karyotype have evidenced an increase in sperm aneuploidy and diploid, although they are related to significant inter-individual variations. On the other hand, this test application in carriers of constitutional chromosome abnormalities allows obtaining accurate data about frequency of chromosomally unbalanced gametes produced in each particular case. FISH tests in human sperm are prescribed in severe male factors, in order to obtain direct information about incidence and production of chromosomally unbalanced gametes before the utilization of assisted reproduction techniques, especially for ICSI (intracytoplasmic sperm injection) candidates.

Y chromosome microdeletion

This test consists of an analysis of regions and genes present in Y chromosome, such as the Azoospermia factor (AZF), which is responsible for proper sperm development and maturation.

Sperm DNA fragmentation testing

Sperm DNA fragmentation refers to ruptures and damage in genetic material of spermatozoa. The higher the number of damage, the lower the integrity of genetic material and, therefore, a lower probability of a successful pregnancy. There are various methods to measure fragmentation levels. In CELAGEM we use the TUNEL test, which is a test with a large clinical projection widely evaluated and recommended by opinion leaders in DNA fragmentation studies. By using this system, it has been established that when an individual has 30% or more of his sperm with DNA fragmented, the likelihood of a successful pregnancy is lower than 1%, in both natural fertilization and assisted reproduction techniques. This test is recommended in the following cases:
• Unexplained (idiopathic) infertility (unknown cause or origin).

• Repeated implantation failures in assisted reproduction techniques.

• Cases where poor embryo quality has been observed.

• Patients with repeated abortions.
• Varicocele.

• Men older than 45 years.

• Febrile seizures in the last 3 months.

Pre-implantation Genetic Diagnosis (PGD)

The pre-implantation genetic diagnosis (PGD) is an innovative detection technique of genetic abnormalities previous to the embryo transfer into a woman’s uterus. It is a technique used as a complement of the in vitro fertilization (IVF). The performance of a PGD is recommended if there is a probability that embryos are suffering certain chromosomal characteristics or genetic diseases. These characteristics may prevent embryo implantation, produce a pregnancy loss, the birth of a child with physical problems and/or mental deficiency or subject to a genetic disease. The PGD may help to prevent these adverse results identifying embryos affected during their development in a laboratory and before being transferred into an IVF cycle. The four main causes recommending a PGD performance are:

• Infertile patients with a prior history of repeated miscarriages.

• Carriers of chromosomal translocations, inversion or other abnormalities, or monogenic diseases.
• IVF-cycle patients older than 35 years, plus five zygotes and no prior history of repeated implantation failures.

• Men with severe alterations in their semen quality (Ornithine aminotransferase –OAT).
Studies generally performed on embryos through PGD techniques are aneuploidy and monogenic disease study.


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• Molecular Biology

• Obstetrics and Gynecology

• Infectious Diseases