Infertility diagnostics – why it is worth carrying out the karyotype analysis?
Karyotype may carry abnormalities resulting in the occurrence of developmental and health disorders. In some cases, these abnormalities do not cause any symptoms in their carrier; problems appear only when she or he plans family. That's why analysing a karyotype is the key element of diagnostics for many infertile couples.
Several dozen years ago, couples who had difficulties in conception were usually left to their own devices. Currently, the physicians’ knowledge of the causes of infertility is much more extensive, and modern medical science has at its disposal effective techniques of assisted reproduction. The determination of the source of infertility is of key importance for the effectiveness of fertility treatment - and, among others, the karyotype analysis can be of assistance.
What is a karyotype?
Karyotype is defined as a set of chromosomes typical for a given species. The human somatic cell contains 46 chromosomes: 22 pairs of so-called autosomes (same chromosomes in women and men) and one pair of sex chromosomes (XY in men, XX in women). If abnormalities occur in the structure or the number of chromosomes, the couple trying for a child may experience problems with conception or multiple miscarriages.
Indications for karyotype analysis
The karyotype analysis allows to identify potential abnormalities in the number or structure of chromosomes. Abnormalities of this type can occur in both sexes, therefore both partners should undergo the analysis. For the karyotype analysis, a small sample of the patient's blood is needed.
The most important indications for performing a karyotype analysis include:
- recurrent miscarriages;
- problems with getting pregnant;
- genetic disorders in the family of a woman or her partner.
What does karyotype tell us about?
In the diagnosis of infertility, the karyotype analysis is performed primarily to determine whether the problems with getting pregnant or miscarriages are the result of a chromosome defect in a woman or her partner. The test also allows the detection of genetic material abnormalities that may be inherited by their common descendants.
Incorrect karyotype results include the unusual size or shape of one or more chromosomes, the number of chromosomes greater or less than 46; separation or breakage of a pair of chromosomes.
The probability of problems with fertility, miscarriages or birth defects in children depends on many factors, including:
- mother's age (the older she is, the older her cells are; in consequence the risk of defects is higher);
- the point of translocation, i.e. rearrangement of chromosome fragments;
- type of defective chromosome pairs.
The results of karyotype analysis - what next?
It is worth emphasizing that changes in the genetic material do not necessarily rule out the chances for having a child - parents with translocations or mosaicism (two cell lines of different genotypes occurring in one individual), can conceive a perfectly healthy child. However, this is not the rule.
If the analysis showed abnormalities in the karyotype of the patient or her partner, the couple should seek a genetic counselling centre in which the specialist in genetics will assess their chances for pregnancy and giving birth to a healthy child.
Transmission of genetic defects occurs in accordance with the rules of inheritance and is governed by statistics. In the case of carrying a specific defect in the karyotype, the probability of passing a specific defect to a child will be determined by the physician - specialist in genetics - explains Robert Gizler, MD, from the InviMed Fertility Clinic in Wroclaw. The specialist will also suggest what other tests should be carried out and which procedures (e.g., IVF with pre-implantation diagnosis) should be considered.
Karyotype defects are present already at the time of conception, they remain for the entire life and are not dependent on age. A separate issue is the problem of de novo aberrations, i.e. changes that appear for the first time at formation of reproductive cells, especially oocytes. The number of such defects increases with age, therefore, in the case of women over 38 years of age participating in IVF programmes, it is recommended to consider pre-implantation diagnosis (PGS) of embryos before they are introduced into the uterine cavity - adds Robert Gizler, MD, from the InviMed Fertility Clinic in Wroclaw.
The causes of decreased female and male fertility may vary, so it is worth undergoing diagnostic tests, such as karyotype analysis, and entrust the fertility treatment using modern techniques of assisted reproduction to physicians from facilities that enjoy a good reputation in the country and abroad; for example InviMed, which has been operating for almost 20 years.