There are many different reproductive options for carrier females who have a higher chance of having a child with Duchenne. It is best that women talk to their OB/GYN and a genetic counselor before becoming pregnant. Learn how to find a genetic counselor in your area, or contact one of Parent Project Muscular Dystrophy’s board-certified genetic counselors who have expertise in Duchenne.
The following are the reproductive options available to carriers:
Have a natural pregnancy, and accept the 25% chance of having a son with Duchenne
For carrier females, with each pregnancy there is a 25% chance of having an affected son (25% affected son; 25% unaffected son; 25% carrier daughter; 25% non-carrier daughter). If the child is known to be male, the chance of having an affected son is thus 50%; if it is female, the chance of a carrier daughter is 50%.
Have a natural pregnancy and pursue testing for sex, followed by testing for the gene mutation in the family (if the mutation in the family is known)
There are two types of prenatal testing that are used to obtain a small sample of the baby’s cells, which can then be tested for the dystrophin gene mutation. These tests are:
- Chorionic villus sampling (CVS) is generally offered between the 10th and 12th weeks of pregnancy. In this procedure, a small piece of the placenta (called the chorionic villi) is removed by going through the mother’s cervix. This procedure may feel similar to a pap smear. Since the placental tissue has the same genetic make-up as the baby, the placental cells can be tested to determine the sex of the baby. If male, those same cells can be tested for the known dystrophin gene mutation in the family.
- Amniocentesis is generally performed starting at 15 weeks, and can be performed through the end of the pregnancy. In this procedure, a needle is inserted through the mother’s abdomen and into the amniotic sac or womb. Some amniotic fluid is removed and cells from the fluid (which belong to the baby) are tested to determine the sex of the baby. If male, those same cells can be tested for the known dystrophin gene mutation in the family.
Both amniocentesis and chorionic villus sampling are invasive procedures, so they have associated risks that may lead to miscarriage. Families considering these tests should discuss the risks and benefits with their doctor or genetic counselor, and request the center’s rate of complications and miscarriage. Prenatal testing is often used to prepare for an affected child, or to make pregnancy termination decisions. Families should consider what they might do with the information, before having prenatal testing.
Have a natural pregnancy and pursue testing for sex, followed by linkage testing (if the mutation in the family is not known)
For families with a confirmed diagnosis of Duchenne, but where genetic testing has not identified a disease-causing change, linkage analysis using the genetic material taken from the chorionic villus sampling or amniocentesis may be available. Linkage analysis uses markers along the gene to determine whether the baby has inherited the “at risk” X chromosome. Linkage analysis is usually only available for families that have at least two affected males. This option involves blood draws from multiple generations, including the affected individuals, so discussing this option prior to a pregnancy is strongly encouraged.
Sperm sorting technologies
Sperm sorting technologies have not been been FDA-approved in the United States, so they are not commonly used. However, you may hear of technologies such as Microsort which is available in other countries. These technologies allow sperm to be sorted based on weight, so X-bearing sperm are separated from Y-bearing sperm, and X-bearing sperm are selected to increase the chance of having a daughter and reduce the risk of having an affected son. Sperm sorting does not sort with 100% certainty, so it cannot guarantee a female child.
Preimplantation Genetic Diagnosis (PGD)
Preimplantation Genetic Diagnosis (PGD) combines in-vitro fertilization (IVF) with genetic testing, with the goal of implanting only unaffected embryos into the mother’s uterus. IVF involves taking egg cells from the mother and sperm cells from the father and creating embryos in the lab (“in vitro”). Cells from each embryo can be removed for genetic testing (preimplantation genetic diagnosis or PGD) and only the unaffected embryos will be implanted into the mother’s uterus. Different women will have different numbers of embryos without the dystrophin gene mutation and will have different rates of success. Speak with your OBGYN or genetic counselor if you are interested in IVF and PGD. You will need to be referred to a reproductive endocrinologist. Please be aware that IVF and PGD are expensive technologies that are not fully covered by all insurance plans.
Egg and sperm donation
Carrier females may consider pregnancy with a donor egg. Egg donation from a non-carrier reduces the chance of having a child with Duchenne to the chance in the general population. Males with Duchenne or Becker may consider using a donor sperm. Sperm donation from an unaffected male reduces the chance of having carrier female children to the chance in the general population.
Adoption is another option that may be explored with your healthcare professional.