Family Planning

A note before you read on

CMT genetics is complex and varies a lot by subtype. Everything here is general and educational, meant to help you ask good questions, not to give you personal odds.

Please work with a genetic counselor and your neurologist before making any medical or reproductive decisions. They can give you figures and options specific to your situation.

How CMT is inherited

CMT is a genetic condition. It is caused by a change (called a variant) in one or more genes that affect the nerves controlling movement and sensation. Because it is genetic, it can be passed from parent to child.

The pattern of inheritance depends on which gene is involved and which type of CMT your family carries. There are a few main patterns. In autosomal dominant CMT, having one copy of the changed gene is enough to cause the condition. CMT1A, the most common subtype, follows this pattern. In autosomal recessive CMT, two copies are needed; a person who carries only one copy usually does not develop CMT but can still pass the variant on. Several CMT4 subtypes follow this pattern.

In X-linked CMT, the changed gene sits on the X chromosome. CMTX1 is the most common X-linked form, and it is inherited differently and can affect men and women differently than the autosomal patterns do. Finally, some children have a de novo variant, a brand new genetic change that neither parent carries. This is less common, but it is important to know it happens.

Because the pattern matters so much for your personal risk, knowing your specific subtype and gene is an important first step. A genetic counselor can interpret your test results and translate them into plain language, including the odds that apply to you.

Getting a genetic diagnosis

If you or a family member has CMT but has not had genetic testing yet, now is a good time to pursue it. Knowing the exact gene variant clarifies the inheritance pattern, tells other family members whether they may want testing too, and opens the door to more precise reproductive planning.

Genetic testing for CMT is usually ordered by a neurologist or a genetic counselor. It may use a gene panel that checks many CMT-related genes at once, or whole-exome sequencing that looks at all protein-coding genes if a panel does not find an answer. Results can take weeks to return and often need a specialist to interpret.

CMT Genie is HNF's program to help you access genetic testing and understand your results. To learn more about the different forms of CMT and what testing looks for, see CMT Types and Subtypes.

Working with a genetic counselor

A genetic counselor is a healthcare professional trained specifically to explain genetic conditions, inheritance risks, and testing options in plain language. For anyone with CMT who is thinking about children, a genetic counselor is one of the most valuable people on your care team.

A counselor can help you understand your specific subtype and what it means for inheritance, and can estimate the likelihood that a child would inherit your variant using figures specific to your situation. They can explain what it actually means for a child to inherit CMT, including how widely severity can vary, walk you through your reproductive options so you can make a fully informed choice, and support other family members who may want testing.

Ask your neurologist for a referral to a board-certified genetic counselor. Many counselors are also available by telehealth, so distance does not have to be a barrier.

Your reproductive options

Families affected by CMT have several options when it comes to having children. None of them is the right choice for everyone. What matters is that you have accurate information and feel supported in whatever path you choose.

Many people with CMT conceive naturally. Pregnancy itself does not cause CMT, and for many people CMT does not prevent a healthy pregnancy. Some find that pregnancy temporarily changes their symptoms, such as balance or nerve-related discomfort, but experiences vary a lot from person to person. Talk with your neurologist and obstetrician about your specific situation.

Preimplantation genetic testing (PGT), sometimes called preimplantation genetic diagnosis, is used alongside in vitro fertilization (IVF). Embryos are tested before transfer so that only embryos without the CMT-causing variant are selected. PGT requires knowing your exact variant in advance, is not available for every CMT type, and depends on the lab and the gene involved. It can be physically demanding and expensive, and insurance coverage varies. A reproductive endocrinologist and a genetic counselor who specializes in reproductive genetics can tell you whether it is an option for you.

If you conceive naturally, you can still have the pregnancy tested for the CMT variant. The two main approaches are chorionic villus sampling (CVS), which tests tissue from the placenta, and amniocentesis, which tests fluid from around the baby. Both are done during pregnancy and carry a small procedural risk. What you do with the results is a deeply personal choice.

Some couples, especially when CMT is on only one side of the family, choose to use donor eggs or donor sperm to avoid passing the variant. Others choose adoption or fostering, a valid and fulfilling path that carries no genetic risk of passing CMT to a child. Each of these decisions involves medical, emotional, and sometimes ethical considerations, and there is no single right answer.

Severity varies, even in one family

One thing worth knowing as you plan is that CMT affects people very differently, even within the same family sharing the same gene variant. Some people have mild symptoms that do not noticeably limit daily life. Others have more pronounced weakness or sensory changes.

Even if a child inherits a CMT variant, there is no way to predict in advance how severely, if at all, they will be affected. A genetic counselor can tell you what is known about symptom variability for your specific subtype.

Emotional support and community

Decisions about family planning with a genetic condition carry real emotional weight. Uncertainty, guilt, hope, and grief can all be part of the process. Connecting with other families who have navigated the same questions can be genuinely steadying.

HNF's GRIN Registry connects people with CMT to research and to a broader community of patients and families. Taking part also helps researchers understand how CMT moves through families across generations.

Research on CMT is advancing. There is no cure today, but HNF and the wider CMT research community are actively working on treatments that target the underlying genetic causes. What is possible for the next generation may look different from what is available now.