Will my baby look like me? Phenotype matching & epigenetics
If you’re planning IVF treatment with donor eggs and/or donor sperm
, you might be wondering if your baby will look like you. With genetics research rapidly advancing, nowadays we realise that heredity is a much more complex issue than we previously expected. In this IVFWEBINAR with dr. Laura García, Medical Director of Clínica Tambre
in Madrid (Spain), you’ll find the answer to one of the most exciting questions: which traits are inherited from the egg donor – and which (if any) from you and your partner.
Donor selection criteria
Choosing an egg donor
is undoubtedly a complex and demanding process. Dr Laura García starts her presentation with describing egg donors’ first selection criteria. In the light of the Spanish law, egg donors have to be less than 35 years old, they have to have a minimum height of 1.55 metres and a maximum BMI of 30 (with the ideal being around 20-25). At Clínica Tambre, potential egg donors are first invited to the meeting with the Nursing Team, during which they are checked in terms of medical conditions and hereditary diseases. They also have the whole egg donation process explained to them in details. If the donor is accepted, she then undergoes an interview with the clinic psychologist- in order to exclude any psychological disorders or mental health problems. If all this process turns out all right, then comes the time of medical tests. These include general health research (e.g. complete blood count, blood group +Rh and serology), gynaecological tests (ultrasound, count of antra follicles, smear test, etc.) and genetic assessment (karyotype, cystic fibrosis, x-fragile and basic recessive mutations as well as the carrier status test of more than 300 genes).
Sperm donors, just like egg donors, have to be less than 35 years old and have the maximum BMI of 30. Their minimum height should be around 1.70 metres. Their first consultation at Clínica Tambre is with the Andrology Team that confirms there are no medical conditions or hereditary diseases within donors’ families as well as explains the sperm donation process to them. Dr. Laura García says that the sperm donor selection process also includes an interview with a psychologist, psychological tests and medical assessment, such as general health research (e.g. complete blood count, blood group +Rh and serology) and andrological tests (sperm count, sperm and urine culture and PCR for chlamydia). If all of the latter is alright, the medical team will follow up with the genetic screening of a sperm donor (including karyotype, basic recessive mutations and the carrier status test of more than 300 conditions).
According to dr. García, the selection of donors is always done by the fertility centre (in order to respect anonymity) and is based on physical characteristics of the recipient, the recipient’s blood type, the doctor-patient communication, genetic matching
and immunological matching (when needed). The latter is conducted when a patient has a story of implantation failures or repetitive miscarriages. In such a case, the KIR test is performed. It is a genetic test that allows assessing the risks of the embryo being rejected by the maternal immune system. If the results show that a patient is a negative prognosis KIR (KIR AA), a specific HLAC1C1 donor has to be selected to improve the chances of the ongoing pregnancy.
Important physical characteristics
Dr Laura García admits that Clínica Tambre offers a wide donor pool – they have around 2500 samples stored in their bank, all respecting very strict security rules. Because of that, they may provide a wide range of phenotypes and – what’s important – no waiting lists for egg or sperm donation treatment. This results in a greater chance of finding the perfect donor in terms of physical characteristics and fertility results.
In order to provide as much information on preferred physical characteristics as possible, patients need to hand in the questionnaire (included in the consent form of the treatment) as well as their photograph (sent or taken at the clinic). The questionnaire is composed of two columns (one devoted to the patient and the other to her partner), and each of them includes such important data as basic body parameters (height, weight), hair type and colour, eyes colour and ethnic group. All of this is to make the donor selection process more effective.
At Clínica Tambre, there is also one important tool used in the donor selection process – namely, Fenomatch® technology. It is Facial Matching with a scientific tool that uses biometric technology to identify facial point distances. It allows for a very accurate selection of the donor regarding concrete facial features.
Dr García explains that in order to select the donor with Fenomatch®, they use a simple photograph of a patient’s face. The Fenomatch® algorithm scans more than 12,000 data points in order to find the donor with the greatest biometric similarity. Fenomatch® is a great way to assure that all aspects of a patient’s appearance are taken into account and thanks to it, donor-conceived children are more likely to look like their parents. Patients receive a report certifying the use of Fenomatch® during the donor selection process.
Epigenetics in donation treatments
In biology, epigenetics is the study of heritable phenotype changes that do not involve alterations in the DNA sequence. As gene expression can be changed depending on the environment, dr. García says that the phenotype can also be determined by our surroundings – and not only gene inheritance.
It is said that epigenetics controls genes. It means that the environment we live in may either activate or silence the determined genes – and this affects each person’s appearance. According to this understanding, epigenetics is hereditary and makes us unique. This is good news for patients undergoing egg or sperm donation treatment. It turns out that even if genes come from the donor, the baby may still look like the recipient. All of this is because of the influence of the environment!
Dr García points our attention to one very simple fact – our minds always try to search for similarities between family members. However, there are families where the kids look like only one of the parents – or none of them. On the other hand, many egg donation patients, after giving birth, say that other people tell them how their baby looks like them.
It is important to remember that donor selection is a very tedious process, including medical, psychological and physical requirements. The detailed selection regarding physical features significantly increases the likelihood that the donor-conceived children will look like their parents. What all egg donation patients should remember first of all is that the baby develops in their environment from the beginning – and this will have a huge influence on the phenotype thanks to epigenetics.