Processing a new diagnosis
A diagnosis of CMT can be a huge shock for yourself, parents, siblings, extended family members and friends. It is normal to feel an overwhelming mix of grief, confusion, anxiety, loneliness and helplessness as your life has been forever changed. Everyone will have different ways of getting through this time but it’s important to know that help and support are available for you, your child and family. Hear advice on processing your diagnosis from a community member with shared experience.
Getting help processing a new diagnosis
There are many ways you can seek support as you process a new diagnosis:
- A psychologist is a university-qualified health professional who can help you talk about your thoughts and feelings to understand and cope with the challenges you and your family are facing. Visit our page on Psychology for more information.
- A counsellor is a trained professional who can help you talk about and work through problems. Visit our page on Counselling for more information.
- A social worker can provide information and support to people experiencing a range of issues including family problems, anxiety, depression, crisis and trauma. Visit our page on Social Work for more information.
- A genetic counsellor can help you understand how CMT is inherited and whether there are any implications for other members of your family. Your specialist will be able to advise whether a genetic counsellor is required. Read more on our page about Genetic Counselling.
- Your state or territory neuromuscular organisation can provide support, advice and information about living with CMT. Read more on our page about state and territory neuromuscular organisations.
- Your GP can talk to you about a mental health plan and how you can use this to help you access the support and services you need. Read more on our page about Wellbeing.
- Other people and families living with CMT have also experienced the emotional rollercoaster that comes with a diagnosis of CMT and are able to understand exactly how you’re feeling. You are not alone. Connect with other people and families living with CMT in The Loop Community on our Forum.
How to talk to your child and others about a new diagnosis
Having a conversation with a loved one about a diagnosis of CMT is not easy. In fact, it will probably be one of the hardest talks you will have. But, like all difficult conversations, it is important and necessary.
There are many reasons why people may not want to have this conversation, mostly centred on wanting to protect their loved ones and themselves.
But avoiding the topic is not helpful. People may have noticed differences and changes that have occurred and/or heard the condition being discussed.
So it is crucial that you have a role in your loved one learning about their/your diagnosis. This will enable you to support them as they process the information and to be on hand to answer any questions they may have. If you are the person with CMT it will provide you with support and someone to talk to. Together, you can learn about the journey ahead.
It will also allow you to:
- provide answers to questions in an age appropriate way
- correct any misinformation they may have heard or read
- show them that you have faith in their ability to handle difficult conversations.
There is no right time to start this conversation. Research suggests the earlier you talk to your loved ones about your/their condition, the more natural the conversation will become. The important part is to pick a time and commit to it.
Some important do’s and don’ts:
- Do be positive but also realistic.
- Do reassure them that no one has done anything wrong and this is not their fault.
- Do tell them they/you will do many wonderful things in their/your life – they/you may just do them differently.
- Do tell the truth. Answer all their questions.
- Do consider your language. Try to avoid negative or emotive words, such as ‘suffering from a condition’.
- Do use daily living examples that they can relate to.
- Don’t avoid answering questions and don’t shut the conversation down.
If you are having difficulty starting the conversation, try asking a couple of questions such as ‘How are you feeling today?’ or ‘Do you know why you/they are having difficulty with your/their muscles?’
Remember, it’s okay to be upset during the conversation but try to avoid breaking down as this will only cause greater distress. And if speaking with a child, remember children are resilient and they generally handle information of this nature far better than adults.
Understanding CMT and how it’s diagnosed
Charcot-Marie-Tooth (CMT) is an umbrella term for a group of conditions that affect the motor (movement) and sensory (sensation) nerves throughout the body. CMT, also known as Hereditary Motor and Sensory Neuropathy (HMSN), was named after the 3 neurologists who first described the condition in 1886, Jean-Martin Charcot, Pierre Marie and Howard Tooth.
CMT is a genetic condition that people are born with but may not show symptoms until later in life. There are many different forms of CMT, with varying age of onset, severity and inheritance patterns, even for people with the same type of CMT. Over 30 different genes have been shown to cause the different types of CMT.
CMT affects about 1 in 2500 live births. This means there is about 10,000 Australians living with CMT and 3 million people worldwide.
What causes CMT?
CMT is a group of conditions that are caused by a change (mutation or fault) in a gene. The faulty genes responsible for CMT contain instructions for the production of particular proteins. These proteins are important for the functioning of the peripheral nerves (the nerves that travel from the brain and spinal column to the rest of your body). The genetic mutation affects the function of the peripheral nerves, meaning the messages between the brain and your arms and legs are disrupted.
Peripheral nerves are made up of 2 types of nerves:
- The motor nerves - control movement by sending messages from the spinal cord to the muscles
- Sensory nerves - carry pain and temperature messages from the hands and feet to the spinal cord.
When these nerves don’t function properly, weakness and wasting of the muscles in the arms and legs occurs, usually below the knees and elbows. In some cases, the damaged sensory nerves reduces the ability to feel heat, cold, and pain.
Damage to peripheral nerves is also known as neuropathy. This is why CMT is also known as Hereditary Motor and Sensory Neuropathy (HMSN).
What are the types of CMT?
There are over 100 different genetic types of CMT however over 80% of CMT falls into 5 main categories:
- CMT Type 1A
- CMT Type 1B
- CMT Type 2
- CMT Type 2A
- CMT X-linked
CMT Type 1 is the most common type and accounts for two thirds of all cases of CMT. Of this group, 60% have Type 1A.
The symptoms of Type 1 and 2 are similar but people living with Type 2 tend to have a wider range of age of onset of the condition and degree of disability.
Children with severe symptoms of CMT are sometimes classified as having CMT Type 3 – Congenital Hypomyelinating Neuropathy (CHN) also known as Dejerine-Sottas disease (DSD).
The classification of CMT into subtypes is complicated and there isn’t a universal classification system used by all doctors around the world.
For more information on the different types of CMT see Muscular Dystrophy Association ‘Types of CMT’
How is CMT diagnosed?
The road to diagnosis usually starts when a person begins to notice changes with their bodies, usually mild lower leg muscle weakness. This is known as the pre-diagnosis phase and for some people it can last years.
Seeking medical advice from your GP, who may refer you to a neurologist, as early as possible can help you manage the physical changes that are occurring and prevent complications.
The first step in diagnosis involves a neurologist taking a detailed patient history, including a family history. Your symptoms and a family history of muscle weakness, reduced reflexes and sensory loss can indicate CMT. People with CMT often have problems with their feet, therefore your neurologist will examine your feet to see if they are showing any signs of the foot problems associated with CMT.
Formal testing will then follow and may include:
- Genetic testing looking for changes in one of the genes that cause CMT. Testing for CMT1a (the most common type of CMT) may be done before NCS and EMG. If CMT1a genetic testing is negative, then EMG and NCS will be done before doing a neuromuscular panel, which looks at a number of genes causing nerve disorders. Further information about genetic testing can be found on the Australian Genomics Health Alliance website.
- Nerve conduction studies (NCS) – this involves placing electrodes (small sensors) on the skin and providing a small electrical stimulus to the nerve to measure the response. The motor (moving) nerves and sensory (feeling) nerves are measured. The speed and strength of the transmitted signals is measured. If the speed of the signal is slower than normal, this indicates CMT Type 1. With CMT Type 2, the speed of the nerve conduction is normal but the strength of the signal is reduced.
- Electromyography (EMG) is used rarely. EMG involves inserting a small needle electrode (sensor) through the skin to measure the electrical activity of the muscles.
Identifying the specific type of CMT can help the person living with the condition and provide additional information about whether further monitoring is required. For example, some types of CMT are at higher risk for hearing problems. However, arriving at this very specific diagnosis is not always straightforward because two people with very different symptoms could have errors in the same gene.
The genetics of CMT
Faults in four genes are largely responsible for the majority of CMT cases. These are:
- CMT1A (PMP22 gene duplication)
- CMT1X (GJBI gene mutation)
- CMT1B (MPZ gene mutation)
- HNPP (PMP22 gene deletion)
- CMT2A (MFN2 gene mutation).
Different types of CMT have different inheritance patterns (how it is passed from parents to children). CMT can be inherited via:
Autosomal dominant pattern
This is the most commonly inherited pattern for CMT with CMT Type 1 and some cases of CMT Type 2. All people have 2 copies of each gene – one inherited from each parent. In autosomal dominant inheritance, it only takes one of the faulty genes from one parent to pass on the condition. This single altered gene is sufficient to over-ride the normal functioning copy of the gene inherited from the other parent. Therefore, the chance of passing on an autosomal dominant condition to an offspring is 50% or 1 in 2.
CMT Type1X is inherited in an X-linked recessive pattern. The altered gene (GJB1) is located on the X-chromosome. Females have two X chromosomes, one inherited from each parent. In most cases females who inherit a faulty GJB1 gene will show no symptoms or only mild symptoms of the condition because the normal gene on the other X chromosome will compensate. Females with one altered GJB1 gene are known as carriers and they can pass the condition on to their sons. The daughters of carriers each have a 1 in 2 chance of being carriers.
Males have only one X chromosome, which they inherit from their mother, and one Y chromosome, which they inherit from their father. If a boy’s mother is a carrier of an altered GJB1 gene there is a 1 in 2 chance that he will inherit this faulty gene. If so, the boy will have CMT because he doesn’t have another X chromosome to over-ride the faulty one.
Autosomal recessive pattern
Less commonly, some CMT Type 2 cases are inherited in an autosomal recessive pattern. This means an individual needs two faulty genes – one from each parent. The parents of an individual with this type of CMT each carry a copy of the altered gene. They are known as ‘carriers’ and typically do not have symptoms of the condition as the other ‘normal’ copy of the gene is enough to prevent the condition developing . For carrier parents to have a child with LGMD Type 2, both parents must pass the altered gene on to their child. If both parents are carriers the likelihood of a child inheriting the condition is 25% or 1 in 4.
For more information on the inheritance of specific types of CMT, see Muscular Dystrophy Association ‘Causes/Inheritance of CMT’
The impact and progression of CMT varies from person to person, even amongst people with the same type of CMT. Some people have little difficulty throughout their lives while other people will required greater assistance.
Most people with CMT are able to continue walking, though sometimes with mobility aids, and have a normal life expectancy.