For many women, pregnancy is a journey filled with joy, as well as hardships. But ultimately, it’s a journey that is rewarded with the miracle of life.
However, not all women are able to conceive or become pregnant, even after years of trying.
Following such upsets are mixed emotions of guilt, self-blame, frustration and anger, which can manifest and affect both husband and wife, and in some instances, even destroy marriages.
All healthy humans are born with 46 chromosomes that are part of every cell in the body. These chromosomes are divided into 22 matching pairs, and one pair of sex chromosomes.
Chromosomes carry genetic material, or DNA, that makes every individual unique. Every individual receives genes from both biological parents; half from the mother and half from the father.
Not all, but some, individuals will inherit the risk of developing certain diseases. For example, alpha-thalassaemia or beta-thalassaemia are inherited diseases that can be passed on from parents to children.
These diseases are due to mutation in the gene(s) related to alpha globin protein and beta globin protein, respectively.
There are many other inherited genetic conditions, such as breast cancer (BRCA 1 and 2), Huntington’s disease, cystic fibrosis, Fragile-X syndrome, just to name a few.
In Malaysia, one in every 20 people is a thalassaemia carrier, while almost one million are affected by the disease.
The possible outcomes for offspring of two people with thalassaemia minor are: a one-in-four chance that a child will inherit a severe form of thalassaemia (thalassaemia major); a one-in-four chance also exists that a child will inherit two normal genes from the parents; and a one-in-two chance exists that the child will inherit a normal gene from one parent and a thalassaemia gene from the other (thalassaemia minor or carrier).
Genetic diseases can generally be separated into two categories: inherited diseases and chromosomal abnormalities.
More common are chromosomal abnormalities, which involve random mutations that make it difficult to carry a child to term.
Chromosomally abnormal embryos have a low rate of implantation in the mother’s womb, often leading to miscarriages. If an abnormal embryo does implant, the pregnancy may still result in miscarriage or the birth of a baby with physical problems, developmental delay, or mental retardation. An example of this is Down Syndrome.
There are several kinds of chromosome abnormalities: a missing piece of a chromosome (deletion), an upside-down chromosome (inversion), too many or too few chromosomes (aneuploidy), and chromosome pieces attached to the wrong chromosome (translocation).
Preimplantation genetic diagnosis (PGD) refers to testing that is performed on embryos from an IVF cycle so that only unaffected embryos are selected for transfer into the womb.
The process involves removing a few cells (three to five cells) from a blastocyst (embryo). PGD allows couples to have their embryos screened for known familial genetic disorders and other abnormalities.
In contrast, preimplantation genetic screening (PGS) is another form of PGD that screens embryos for abnormal number of chromosomes. Abnormal number of chromosomes has been shown to be the cause of most unexplained miscarriages.
The main indications for PGS are women over the age of 35, couples who have experienced several failed IVF cycles, couples with recurrent miscarriages, couples who have a prior pregnancy with chromosome abnormality, couples with unexplained infertility, men with severe male factor infertility, and either one of the couple is a carrier of an X-linked disease/ structural chromosomal rearrangement, or any couple who simply wants to have a higher pregnancy rate.
The rapid rise of the use of PGS is due to the realisation that poor implantation, pregnancy and high miscarriage rates are primarily due to aneuploidy (too many or too few chromosomes in the embryo).
More effective embryo-freezing technologies and the realisation that frozen embryo transfer yields higher implantation rates than fresh embryo transfer, and increased awareness amongst doctors and patients, have contributed to the rapid rise in the use of PGS in Asia.
Statistics reveal that the majority of miscarriages are caused by genetic abnormalities, and many of us are not even aware that we may be carrying a dysfunctional gene. Using PGD/PGS, couples who carry abnormal an number of chromosomes or genes (eg. Down syndrome, Edwards syndrome, Turner syndrome, thalassaemia) may finally have a chance to achieve a successful pregnancy and a normal baby.
Genetic screening prior to IVF can help countless couples who have experienced multiple miscarriages or have gone through unsuccessful cycles of IVF treatment to dramatically increase their chances of pregnancy and ultimately giving birth to a healthy baby.
The use of Ion Torrent system which enables both PGD and PGS tests to be done simultaneously with only one single sample from the embryo, avoids the potential of injuring the embryo due to having to do separate tests for PGD and PGS in a patient who requires both.
Trying to get pregnant can be stressful and overcoming miscarriage can be even more so.
Seek early consultation advice and do fertility assessment to put time on your side because women 35 and older are at a higher risk of producing aneuploidy embryos, which results in implantation failure, increased risk of miscarriages or the birth of a child with a chromosome abnormality such as Down syndrome.
Dr Colin Lee is a consultant gynaecologist and fertility specialist. For further information, e-mail firstname.lastname@example.org. The information provided is for educational and communication purposes only and it should not be construed as personal medical advice. Information published in this article is not intended to replace, supplant or augment a consultation with a health professional regarding the reader’s own medical care. The Star disclaims all responsibility for any losses, damage to property or personal injury suffered directly or indirectly from reliance on such information.