What happens exactly in chromosome translocations?

We recently spoke to esteemed fertility specialist and consultant gynaecologist, Mr Mahantesh Karoshi, to find out about chromosomes, including where they typically come from, what occurs in chromosome translocations, and reveals whether or not the risk of miscarriage is increased when either a mother or father has a balanced chromosome translocation.

Where do chromosomes come from?

Normally, one half of chromosomes come from the mother and the other half from the father. Pieces of the chromosome pairs split so that the baby receives genetic material from each parent.

What happens exactly in chromosome translocations?

In chromosome translocations, some sections of chromosomes change their geographical position without any loss or gain of importance. In translocation, there is no loss of genetic material, as the chromosomes sections are simply joined at the wrong position. When the number of chromosomes is correct, but a portion of one of the chromosomes has attached incorrectly, it is referred to as a balanced translocation.

Roughly how many people suffer from balanced translocation?

Roughly one in 500 people in the general population suffer from this. Most individuals with balanced translocation suffer no ill effects and are often undiagnosed until they experience fertility issues. Ruling out the possibility of translocation will assist to understand the risk of recurrence.

Is the risk of miscarriage higher when a parent has a balanced chromosome translocation?

When one member of a couple carries a balanced chromosome translocation, the risk of having a miscarriage is approximately doubled. In three to five per cent of couples with recurrent miscarriage, one partner has a balanced translocation.

Family history of miscarriages, such as patient’s mother or her sister having had the same problem, should also be taken into consideration. When a balanced translocation is identified and if the affected woman miscarries, it is useful to karyotype the miscarried pregnancy tissue to see if it was the result of translocation.

When either the male or female partner has a balanced translocation, the risk of miscarriage increases to 20 per cent, sometimes 30 per cent, or even 50 per cent.

What are the different fertility options for a woman with balanced translocation?

There are, thankfully, many fertility options for a woman with balanced translocation. The main ones include the following:

• IVF-PGD (preimplantation genetic diagnosis) – improves the chances for a success pregnancy and live birth and maintains a genetic link to parents.
• Gamete or embryo donation – eliminates risks associated with balanced translocation but treatment costs are higher, and there is no genetic link to both parents.

Mr Mahantesh Karoshi is a highly experienced London-based consultant gynaecologist who specialises in infertility issues in women. Consult with him today via his Top Doctors profile.