The reasons for requesting pre-fertilization or pre- implantation diagnosis coincide, in principle, with those that lead to the request for prenatal diagnosis. One part of the requests concerns the search for chromosomal anomalies by couples in which the high age of the woman is accompanied by an increased risk of Down’s syndrome in the unborn child or by women in whom there have been repeated miscarriages suspected to be due to chromosomal alterations in the fetus. A second large volume of requests concerns couples with a high risk of transmitting an inherited genetic disease to their off spring. Until a few years ago, the legislation in force in Italy allowed access to medically assisted procreation (MAP) only for couples unable to procreate physiologically. This means that most couples at high risk of transmitting mutations responsible for hereditary genetic diseases to their offspring, not having access to medically assisted procreation (because they were able to procreate), had no possibility to carry out a pre-fertilization diagnosis or pre-implantation diagnosis. After a series of judicial sentences and in analogy with European legislation, today, all couples who request it have access to MAP and, consequently, to pre-implantation diagnosis. Therefore, couples at risk of genetic diseases can choose between the prenatal diagnosis pathway (invasive or non-invasive) and that of MAP with pre-implantation diagnosis. In these couples, the pre-test consultation is highly delicate because, in addition to the more strictly analytical aspects, it is necessary to make the couples understand that the path of MAP is not free from risks, including ovarian hyperstimulation syndrome. Women who resort to MAP receive an intense hormonal stimulation (which may not be tolerated due to side effects) aimed at inducing the production of numerous oocytes, among which will be selected those that morphologically appear more suitable for fertilization. There are ethical and religious reasons on the other side of the scale. Although prenatal diagnostic techniques are now commonly used for diagnosing genetic abnormalities at the fetal level (and non-invasive diagnosis is a further substantial contribution), if a sick fetus is detected, many couples will have the choice of continuing the pregnancy or therapeutic interruption. Only for very few dis eases, in fact, in utero therapy is available (e.g., adrenal hyperplasia from 21-hydroxylase deficiency) or therapies that can be implemented from birth to counteract the effects of the dis ease (e.g., hemophilia can be treated from birth with recombinant deficient factor). Many couples at risk of genetic disease are forced to face repeated interruptions of pregnancy before they can have a healthy baby. Therefore, the possibility of choosing a prenatal diagnosis greatly benefits these couples, avoiding their recourse to therapeutic abortion. It must also be considered that, in some populations, prenatal diagnosis is not accepted because of the ethical/moral, or religious problems associated with the termination of pregnancy.

From a methodological point of view, the pre- implantation diagnosis does not offer particular difficulties for an advanced laboratory of clinical molecular biology. Once the in vitro fertilization is obtained, two cells (blastomeres) are taken from the embryo in the early stages of development, whose DNA will be analyzed. With the latest MAP protocols, it is also possible to take the sample later, obtaining more cells for analysis. After analysis, unaffected embryos can be implanted.

Depending on the type of diagnosis to be made, the most appropriate technology will be used. For example, to search for parental mutations in the gene-disease in the case of hereditary genetic diseases, the same methods used in prenatal diagnosis will be used (amplifying the gene of interest by PCR and sequencing to identify any mutation). On the other hand, the new technology of comparative genomic hybridization on microarrays (CGH-array) can be used to analyze chromosomal alterations. This technology makes it possible to identify all alterations linked to an increase or reduction in DNA content (trisomies and other aneuploidies, deletions, duplications, balanced translocations), which account for about 95% of all chromosomal alterations. In short, the entire DNA extracted from embryonic cells is analyzed compared to DNA from cells obtained from a healthy subject. The DNA is hybridized by a series of probes adsorbed on a tiny solid support that bind all the genome traits, labeled with different fluorochromes (for embryonic cells and DNA from healthy cells). Then, the image is acquired by a scanner and processed by a bioinformatics system. For each stretch of hybridized DNA, a light signal will be generated whose intensity will be proportional to the amount of DNA. By comparing the signal between the healthy sample and the sample from embryonic cells, it will be determined for each tract how many copies are present (higher signal in all probes that hybridize chromosome 21 in case of trisomy 21, the weaker signal in case of deletion of a tract, etc.).

اخر الاخبار

اخبار العتبة العباسية المقدسة

قسم شؤون المعارف يصدر كتابًا حول قصيدة الفرزدق في مدح الإمام زين العابدين (عليه السلام)

الأمين العام للعتبة العباسية المقدسة يشارك في حفل افتتاح مشروع تجديد الإيوان الذهبي بحرم أمير المؤمنين (عليه السلام)

المجمع العلمي يطلق ورشًا تطويرية لقرّاء الختمات الرمضانية في بابل

سماحة السيد الصافي يشيد بجهود دار علوم نهج البلاغة ويوجه باعتماد أحد مناهجها وتوسيع طباعة كراس عهد مالك الأشتر

المزيد

الآخبار الصحية

هل توقيت نشاطك اليومي يؤثر على صحة دماغك؟.. العلماء يجيبون

"مشروب محبوب" يخفي فوائد لا يعرفها كثيرون

طبيب يكشف 5 أنواع للسعال.. بعضها خطير

نقص فيتامينات "خفي".. قد يفسّر التعب والتنميل وقلة التركيز

المزيد

الآخبار التكنلوجية

دراسة: تغيّرات في أسلوب القيادة قد تكشف مبكرا عن الخرف !

عمرها 773 ألف سنة.. اكتشاف أقدم أحافير بشرية في المغرب

"اختراق علمي".. اختبار دم في منزلك قد يكشف ألزهايمر

ماذا يحدث للجسم عند قطع الكافيين فجأة؟

المزيد

مواضيع ذات صلة

Pepsinogen

Parkinson disease testing

Papanicolaou smear (Pap smear, Pap test, Cytologic test for cancer, Liquid-based cervical cytology [LBCC], ThinPrep)

Carrier Diagnosis

oximetry (Pulse oximetry, Oxygen saturation)

5′-nucleotidase

neutrophil gelatinase–associated lipocalin (NGAL, Lipocalin-2)

neutrophil antibody screen (Granulocyte antibodies, Polymorphonucleocyte antibodies [PMN ab], Antigranulocyte antibodies, Antineutrophil antibodies, Neutrophil antibodies, Leukoagglutinin)

Myoglobin

metal testing (lead, arsenic, mercury)

Clinical Molecular Biology: Diagnosis of Susceptibility

Laboratory diagnosis of SARS-CoV-2 : Point of Care Molecular Test