Genetic Aspects of Donor Selection

Abstract

When the first edition of this book was published in 1997, oocyte donation was relatively new, and little had been written about the genetic screening of oocyte donors. No guidelines from professional societies yet existed, and there was no general consensus about what sort of screening was appropriate. Over the past ∼13 years, much has happened – both in the world of oocyte donation as well as in genetics. There are now reasonably well-established and accepted guidelines for oocyte donor screening, and studies that have looked into recipient preferences for genetic screening have also been published. In addition, the number and type of genetic tests that one may consider in the context of egg donor screening have increased over the past decade.

Recipients, being mostly highly educated and successful people, are typically upon focused donor “quality,” and many have very specific ideas about which attributes they would like their donor to possess (or not possess). Many recipients are willing to pay more money for eggs from women with desirable attributes, such as academic achievement and musical or other talent. They also tend to be aware that testing for a variety of genetic disease is becoming increasingly available, and many are keenly interested in knowing which genetic screening and/or testing has been performed. Therefore, it is important for professionals involved in the process of egg donation to have carefully considered genetic screening and testing.

Appendices

Appendices

Appendix A

Genetic Screening Form for Oocyte Donors and Partners of Recipients

Name:________________________________

Date:_________________________________

Birthdate:_____/_____/_____

Pregnancy history: (please list all the times you have been pregnant and the outcomes) _______________________________________________

Family ethnic background:____________________________________________________________________

Please indicate all relevant information in the following tables. When the requested information is unknown, please say so. If comments are needed, please make them. Remember that we are interested in your genetic background. If any relevant family member is adopted, please say so.

Relation	Age if living	Age at death	Cause of death
Grandfather (pat)
Grandmother (pat)
Grandfather (mat)
Grandmother (mat)
Father
Mother
Brothers
Sisters

Family Genetic History

	Self	Mother	Father	Siblings	Comments
Familial conditions
High blood pressure
Heart disease
Deafness
Blindness
Severe arthritis
Juvenile diabetes
Alcoholism
Schizophrenia or manic depression
Epilepsy
Alzheimer’s disease
Other (specify)
Malformations
Cleft lip or palate
Heart defect
Clubfoot
Spina bifida
Other (specify)
Mendelian disorders
Color blindness
Cystic fibrosis
Hemophilia
Muscular dystrophy
Sickle cell anemia
Huntington’s disease
Polycystic kidney disease
Glaucoma
Tay-Sachs disease

Please take the time to explain any other problems or conditions in your family history which you feel could pertain to the health of future generations.

Appendix B: Genetic Information for Recipients

Basic Genetic Principles for Participants in Gamete Donation

It is our policy to inform all participants in the oocyte or sperm donation program about our reasoning and methods for the genetic screening of donors. We do this in part to reassure you that we do everything that is reasonably possible to minimize the risk of transmission of genetic diseases and conditions. In addition, we want all participants to be aware of the limitations of genetic screening.

Human genetic disease can be divided into three major categories. The first of these is chromosomal: All of our genetic information is contained in 23 pairs of chromosomes that are present in all the cells of our bodies. Errors in the number of chromosomes can occur during the production of sperm and eggs. A well-known example of this category of genetic illness is Down’s syndrome. Chromosomal disorders in general do not run in families. Rather, they happen more or less at random with the main risk factor for occurrence being increasing maternal age. Because of the association of chromosome abnormalities with maternal age, all of our oocyte donors are under the age of 35. While chromosome abnormalities can be tested for in pregnancies by maternal serum screening and amniocentesis, we cannot eliminate the risk of their occurrence. Luckily, the chance of having a baby affected with a chromosomal disorder is quite low (about 1/300–1/1,000).

The second major area of genetic disease is “single gene disorders.” These are conditions that are caused by an abnormality in a single gene, and these can be further divided into two groups, recessive and dominant. With recessive single gene disorders, both parents must be carriers in order to have an affected child. When both parents are carriers, the risk of having an affected child is 1 in 4 or 25 %. Cystic fibrosis and sickle cell anemia are two well-known examples. Some of these disorders occur in specific ethnic groups (White Europeans are frequently carriers of cystic fibrosis. African Americans are frequently carriers of sickle cell anemia, and Jews of European decent are frequently carriers of Tay-Sachs.) For this reason, we test potential donors for those recessive conditions for which they are at increased risk. In addition, we question potential donors about the presence of any of these conditions in their families. For many rare conditions, there is no carrier testing available. Luckily, the chances of both parents being carriers for the same rare gene are very low.

With dominant single gene conditions, only one parent must have the abnormal gene. We ask all donors about the presence of such conditions in themselves and in their families. Donors from families with dominant genetic conditions are excluded.

The third major area of genetic disease is called “multifactorial.” What is meant by this term is that the trait or condition in question is under some level of genetic control but that there are other factors such environment and chance involved as well. An example of this is the common malformation of cleft lip and/or cleft palate. There are probably several genes as well as environmental factors involved in this condition. Close relatives of someone with cleft lip and palate are at increased risk of having cleft lip and or palate, but the degree of that risk does not fit any simple model. Many other ­malformations as well as perhaps most common diseases fall into the category of “multifactorial.” The list of things inherited in a multifactorial manner would include diabetes, heart disease, high blood pressure, some forms of cancer, and even such things as myopia and dental malocclusion. Behavioral traits can be inherited in a multifactorial manner as well. The list here probably includes severe mental illnesses such as schizophrenia as well as conditions such as alcoholism and even homosexuality. We screen all potential donors by asking them if they or any family members have any relevant conditions. When the potential donor or her immediate relatives have any of these conditions, they are excluded.

By following the above guidelines, we believe we have done everything reasonably possible to insure the good genetic health of babies born from egg donors. There is no doubt that the measures we take go way beyond what most couples who undertake “normal” parenthood do to insure good genetic health of their children. However, it would be unrealistic to believe that it is possible to prevent all genetic disease. Most malformations occur in the absence of any family history. The same is true for many dominant and recessive single gene conditions and for chromosome abnormalities. The good news is that the risk for genetic disease and malformation is, in general, quite low.