Having in mind the couples with high risk of a sex-linked genetic disease in their children, the INVICTA Clinics introduced a special type of preimplantation diagnosis – PGD X-linked. In cases where the high risk of passing the defective gene variant on to the child, the patients can decide on performing in vitro fertilisation with genetic embryo testing. This way the couple increase their chances of obtaining a normal pregnancy and giving birth to a healthy child. INVICTA is the only centre in Poland which carries out the tests of this type.
The X chromosome contains many genes that are important for proper development. Over 400 sex-linked disorders with various inheritance pattern have been described. Some of them are characterised by the severe course with shortened lifespan or imminent disability for the affected individual. The Y chromosome is smaller and has less genes, but it is important for the development of the male sex. There are very few diseases linked to the Y chromosome, mainly chromosomal rearrangements in the AZF region. Females have two X chromosomes (XX). If one of the genes located on the X chromosome has a mutation, the normal gene on the other X chromosome balances its occurrence. It happens sometimes that female carriers of X-linked recessive diseases show clinical symptoms of the disease. In case of X-linked dominant disorders, symptoms occur in men and women, but in women with varying intensity. Men have an X chromosome and a Y chromosome (XY). If one gene on the man’s X chromosome has a mutation, it lacks the second copy which could compensate for its presence. This means that such man will always be affected by the fully symptomatic disease in case of sex-linked diseases – as long as he has a normal karyotype.
The risk of a sex-linked disease occurs when a woman trying for a child is a carrier of a mutation in a gene on the X chromosome or a male partner is affected by the abnormality of the Y chromosome. If the change is inherited in a sex-linked recessive way, it will be a threat for male children, as a boy always inherits the X chromosome from his mother (with or without the mutation), and the Y chromosome from his father – says Karolina Ochman, MD, from the INVICTA Fertility Clinic.
The couple with confirmed burden of sex-linked disease can significantly reduce the risk of its occurrence in their child by performing the so-called preimplantation diagnosis. In such cases, in the framework of in vitro programme, the genetic testing of embryos is carried out. To date, prospective parents could either opt for the so-called sex selection and select only female embryos, or request the diagnostics tailored to specific changes in the DNA. The PGD X-linked test allows to indirectly state the embryo’s genetic status by determining which sex chromosome (normal or abnormal) has been inherited by the embryo – explains Sebastian Pukszta, MD, from INVICTA Genetics Laboratory. Such narrowing of the test scope allows the significant cost reduction and increases its availability to patients. Depending on the situation, the couple can have both the daughter and the son, because they do not have to look solely at the baby’s sex when selecting an embryo for transfer – adds Doctor Pukszta. Preimplantation diagnosis in INVICTA is based on an innovative technology – next-generation sequencing, which is today considered the reference method for all others. The experts assure that this technique has exceptional sensitivity and reliability of the results.
The cost of the test is 5,990 PLN. The couple has the opportunity to combine the study with the so-called screening of chromosomes for the most common syndromes for the price of 9,990 PLN for both tests.
INVICTA Genetics Laboratory
INVICTA is the only centre in Poland which carries out its own preimplantation diagnosis. It has more than 10 years of experience in this field, and its activity is reported to the international organisation, ESHRE PGD Consortium. In terms of the number of performed tests INVICTA is on the sixth place in the world. As a pioneer on a global scale, in 2013 it introduced into the clinical practice the PGS and PGD diagnosis using NGS technique. The quality of INVICTA preimplantation testing is confirmed by international certificates (UK NEQAS, CQAS). The company has a dedicated team of scientists which conducts research projects and develops knowledge on PGD and PGS diagnostics.