By Jill K. Powell, M.D.
When a genetic condition is diagnosed in an individual or is known to run in the family, there are often questions about implications for passing the condition on to future offspring (children, grandchildren and beyond). Questions can arise about whether any options exist to predict the likelihood that a future child would be affected by the condition, or even whether options exist to decrease or avoid the risk of future child having the condition.
This blog is intended to provide information about the options that are available to individuals and families with genetic conditions such as ectodermal dysplasias. Decisions about reproduction and family building are both personal and sensitive. They can vary greatly from having no desire to alter the chances of having an affected child, to wanting to make the diagnosis prenatally for any number of reasons, to wanting to use assisted reproduction advances to minimize/avoid the chance of passing on the condition to future generations.
Regardless of the above, there are often benefits to knowing whether a fetus is affected or not by a condition so that the pregnancy can be monitored appropriately and delivery and newborn care can be planned in an appropriate setting and location.
The options for early, accurate prenatal diagnosis of x-linked hypohidrotic ectodermal dysplasia (XLHED) in particular take on even more importance since the exciting announcement this year of the successful CURE of some of the skin issues in twin infant boys with XLHED treated DURING pregnancy, since prenatal (but unfortunately not newborn) treatment seems to be necessary to allow the sweat glands in these individuals to develop.
When Ectodermal Dysplasias Can be Detected
There are three stages at which some ectodermal dysplasias can be diagnosed: after birth (postnatally), during pregnancy after implantation (prenatal or antenatal diagnosis), or before implantation (preimplantation genetic diagnosis). Postnatal diagnosis would be expected in individuals with a de novo (spontaneous) mutation that previously did not exist in either parent’s DNA, or in children of parents who have such mild or asymptomatic symptoms that they did not know they carried the DNA mutation (for example, mildly or unaffected women with XLHED who did not know they had it).
Prenatal diagnosis can be made for some conditions by ultrasound evaluation of the fetus if issues associated with the syndrome can be seen by ultrasound (for example, very underdeveloped nasal bridge in HED or cleft lip/palate and classic hand and feet appearance in ectrodactyly-ectodermal dysplasia-clefting (EEC) syndrome). The timing and likelihood of these ultrasound findings being noted depends on the severity of the abnormality and the knowledge and expertise of the sonographer and obstetric providers.
In conditions where a specific single gene mutation has been identified as the cause of the condition, prenatal diagnosis may be available by testing the cells in the developing placenta (chorionic villus sampling or CVS) at 10-13 weeks from conception or by testing the cells in the amniotic fluid (amniocentesis) at 15-20 weeks (or beyond) from conception. But, it is NOT included in routine screening of women so would specifically need to be ordered. Any procedure involves some risks, including these, and you should discuss further details before considering.
If an individual wanted to test an embryo BEFORE it was implanted in the uterus to allow for further development, you would see a reproductive endocrinologist prior to pregnancy for preimplantation genetic diagnosis (PGD). Rather than spontaneous “in vivo” fertilization, PGD requires assisted reproduction with in vitro fertilization (IVF) by using fertility medications to stimulate ovarian egg (oocyte) development, then egg retrieval, followed by fertilization of the egg and sperm in the lab, testing of a few cells from taken from fertilized embryo to see if the genetic mutation is present or not, and then placing an unaffected embryo or unaffected embryos back through the cervix into the uterine cavity for implantation.
Summary of Options
Spontaneous conception/pregnancy with no assisted reproduction with:
- No genetic testing
- Chorionic Villus Sampling (CVS)
- Postnatal testing/diagnosis
Assisted Reproduction with:
- In Vitro Fertilization (IVF) with Preimplantation Genetic Diagnosis (PGD)
- Donor sperm if male with ectodermal dysplasia (typically done with office intrauterine insemination, donor sperm introduced into unaffected female’s uterus for her to carry the pregnancy)
- Donor egg if female with ectodermal dysplasia (unaffected egg fertilized with male’s sperm, implanted into affected female’s uterus for her to carry the pregnancy)
- Donor embryo with IVF. Some couples select this option to both avoid the risk of passing the DNA mutation from the affected parent to their offspring while limiting the steep costs of donor egg or sperm and PGD and/or to adopt extra, fertilized embryos from other couples who have undergone IVF that would otherwise be discarded or frozen and stored long-term.
There are a variety of family-building options for individuals with ectodermal dyplasias. Not all options are pertinent to every syndrome, and personal factors such as health status, fertility status (including age), religious considerations, financial considerations, and other factors all play a role in an individual/couple’s decision-making about building a family.
Geneticists, genetic counselors, reproductive endocrinologists and maternal-fetal medicine physicians (also called perinatologists or high-risk OB specialists) are excellent resources for additional information about specific diagnoses and testing available. Options are maximized when discussed prior to pregnancy and each of the above specialists typically will see people for preconception counseling consultations.
Prenatal diagnosis can be used for pregnancy surveillance, decisions about mode, location or timing of delivery, decisions about whether to continue the pregnancy for some individuals, and even decisions about prenatal treatment of an affected fetus in the future. Of course, there are many other reasons besides genetic testing to seek care before pregnancy to optimize the health of both mom and baby.
– Dr. Powell is a guest blogger for the National Foundation for Ectodermal Dysplasias (NFED). She is an Adjunct Associate Professor in the Department of Obstetrics, Gynecology and Women’s Health at Saint Louis University School of Medicine and has a secondary appointment as Assistant Professor in the Department of Pediatrics there. She has been a member of the NFED Scientific Advisory Council since 2002.