Family Planning

When an individual is diagnosed with myotonic dystrophy (DM), decisions about starting a family can be complex.The risks of passing on the disease are high, and the consequences can be severe: a parent with myotonic dystrophy has a 50% chance of passing on the disease to their off-spring even if that parent shows little or no symptoms. In addition, children born to mothers with DM1 have increased risk of congenital DM1, a severe and potentially life-threatening form of the disease that presents at birth. (Please see Cause of Myotonic Dystrophy or further information on how the disease is inherited).  

Discussing family planning issues with a genetic counselor can help individuals make an informed decision. Counselors can explain how myotonic dystrophy is inherited, describe the risks of attempting a pregnancy or having particular testing done, interpret complex medical information, and ensure that prospective parents are aware of all options available to them. These options include the following:

Preimplantation genetic diagnosis (also known as PGD) - is the diagnosis of a genetic condition prior to the achievement of a pregnancy. This form of testing is done on a woman's eggs using in vitro fertilizationEggs are obtained from the female after her ovaries have been stimulated with infertility drugs. While under sedation and with the use of ultrasound guidance, a needle is inserted into the ovaries and eggs are aspirated. These eggs are then fertilized in the laboratory (in-vitro) with the partner's sperm and the developing embryos are cultured from three to six days. Unfertilized eggs are retrieved from the woman by a doctor and are fertilized outside the womb in a laboratory. On Day 3, when an embyro is at the 6-8 cell stage, the eggs are biopsied, and tested for DM. On Day 5, the results of the test, the woman's medical history and possibly her age and the health of the remaining embryos will determine if and how many embryos are implanted back into the woman's uterus. Only non DM-affected fertilized eggs are implanted. The fertilized eggs that test positive for myotonic dystrophy will either be discarded or can be sent to several medical research labs throughout the United States that can use these embyos to advance medical research on myotonic dystrophy. To find out more about embryo donations, send an email to questions@myotonic.com and we can put you in touch with these researchers.

Prenatal diagnosis - Parents wishing to find out during pregnancy whether their fetus has inherited the myotonic dystrophy gene can undergo prenatal testing. Two types of tests are available:

  • Chorionic villus sampling (CVS) - The doctor removes a piece of tissue from the edge of the placenta using a needle inserted through the abdomen or vagina. The sampled tissue contains the same genetic information as the fetus; the DNA is isolated and tested for the presence of the myotonic dystrophy mutation. The test can be done in the first trimester (generally around 10 weeks into the pregnancy) and results are typically available within 1-2 weeks.
  • Amniocentesis - This procedure involves removal by needle aspiration of a fluid sample from the womb that contains skin cells shed by the fetus.Those cells are then grown in the lab to provide DNA for testing.The test is typically done at 15 weeks into the pregnancy and can take 2-3 weeks for results to become available.

Prenatal testing carries some risk. It was previously thought that CVS caused a higher rate of miscarriage than amniocentesis, although recent studies suggest the risk is roughly the same for both types of testing (between 1 in 200 and 1 in 400 pregnancies). A genetic counselor or obstetrician can provide current estimates of the risks of prenatal testing.

No testing - Some individuals choose not to do testing, but receive special medical attention during and after pregnancy.

Mothers who have DM1 should be closely monitored during pregnancy because they have an elevated risk of having a child with congenital DM1. In these cases, excessive amniotic fluid (hydramnios) can accumulate, which can usually be seen during ultrasound examination. Decreased fetal movement is frequently noted. Also, breech presentation and weak uterine contractions can cause long or difficult deliveries, often resulting in Caesarean births.

Newborns with congenital myotonic dystrophy require immediate intensive medical support.  Delivery at a medical center with high-risk neonatal support may be recommended.

Regardless of whether or not testing is done, individuals with a family history or symptoms of myotonic dystrophy should inform their obstetrician so the medical team can prepare for the possible complications seen with these children.

Adoption or egg/sperm donation - Individuals who are not willing to accept the potential risks of natural parenthood may choose to adopt or have egg/sperm donation from a person who does not carry the myotonic dystrophy mutation.