We turned to Dr Spies from Vida Fertility to help us understand the role of epigenetics within fertility and IVF.
Before you talk to us about Epigenetics, can you talk to us about genetics and their role/importance in the human body?
The complete function of our body is determined by the information that is stored in the genes. The genes give instructions to the cells of how to work and how to express their different functions. The sequence of the gene arrangement, the so-called genetic code, is 99.9% identical in all humans.
Can you explain the difference between genes and DNA?
The smallest particle of the genetic information is the DNA, which are 4 different acids called adenine, cytosine, guanine, and thymine (described by the letters A, C, G and T). The sequences of these acids form the genes which are later translated into proteins and give the information to the cells of how to fulfil their function.
You can imagine the DNA as letters of a book (the human genome has about 3 billions of letters) and the genes as the words (in totally, we have around 21000 genes). This so-called genetic code is identical for all humans (and very similar to those of other species), with only very slight differences between each one of us.
The genes then are organized in chromosomes which store the complete information in a very compacted way inside the cells. Every cell of our body has 46 chromosomes (organized in 23 pairs of chromosomes), with exception of the gametes (egg and sperm cells) which contain only 23 chromosomes (one of them being the sex chromosome X or Y).
You can’t change your inherited genes, can you?
There is no way to change the sequence of the genes you inherited, but there exist some ways to modify the expression of the genes, the way they fulfil their function. These modifications are based on the epigenetics.
Can you explain in simple terms what Epigenetics mean?
Epigenetics means “on top of genetics” and describes a way of modifying the activity of the DNA without changing the order of the DNA sequence. It can change the way of how the information given in the genetic code is traduced and how the information is going to be expressed.
It seems that epigenetic changes – the so-called epigenetics marks – can be produced in each individual, but that they can also be transmitted to future generations.
If we go back to the example of letters and words, the epigenetics will correspond to accents you can put on the words and like this change their meanings.
What is the connection between Epigenetics and fertility?
There exist many epigenetic changes that can have an influence on male and female fertility. Most of them are related to environmental factors, like the diet, the intake of alcohol, drugs, smoking, sedentariness, etc. or so-called endocrine disruptors, such as insulin resistance, alterations in thyroid function, lack of male or female hormones and so on.
The good news is that many of these factors can also be changed in the other direction, that means by having a healthy lifestyle and controlling well the hormone functions we can produce positive effects on fertility.
How does IVF relate to Epigenetics?
Most of the children born through techniques like IVF or ICSI have a completely normal development and grow healthy. Nevertheless, there are some investigations indicating that the have a higher tendency to have a lower birth weight and an increase in the incidence of some rare syndromes like Beckwith-Wiedemann or Angelman which are related to epigenetics.
We don’t know which part of the process of assisted reproduction technique in humans can provoke these alterations in epigenetics, because there is manipulation in many parts of the fecundation and the early development of the embryo, for example the use of hormones for ovarian stimulation, in vitro maturation of the eggs, the microinjection of the spermatozoids or the in vitro culture of the embryos. All of these processes can change epigenetics, but it must be said that most studies available at the moment are made in animal models and we don’t know the real impact in human development.
Can you talk to us about the connection between Epigenetic and mothers pregnant with a donor egg?
In egg donation treatment the genetic sequence comes from the egg donor and the male partner/sperm donor. That means that the mother doesn’t give her genetic sequence directly to the baby.
Nevertheless, the impact of the mother during all the pregnancy can produce changes in epigenetics and have an influence on how the baby’s genes will be expressed after the pregnancy. That means that the mothers behavior during the 9 months of pregnancy, for example what she eats, drinks, the exposure to stress or to toxic environment, has an important influence on the child.
Does stress affect epigenetics?
A lot of changes in epigenetics are due to environmental factors, such as changes in or lack of nutrition, the quality of the air, alcohol or drug consume or the exposure to stress. For example, in animal studies there has been observed that a prolonged exposure to stress in newborn may lead to depressive symptoms in adult life. There is still lack of evidence of the real impact of stress to epigenetics, but it’s supposed to play an important role and can induce long-lasting changes in the expression of certain genes.
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