Neuropathies are nervous system disorders that cause nerve damage. They affect the peripheral nerves, including nerves beyond the brain and spinal cord.
Hereditary neuropathies are passed on genetically from parent to child. They’re sometimes called inherited neuropathies. Neuropathies can also be nonhereditary, or acquired. Acquired neuropathies are caused by other conditions, such as diabetes, thyroid disease, or alcohol use disorder. Idiopathic neuropathies have no apparent cause.
Hereditary and nonhereditary neuropathies have similar symptoms.
Symptoms of hereditary neuropathy depend on the group of nerves affected. They can affect the motor, sensory, and autonomic nerves. Sometimes, they affect more than one nerve group. For instance, Charcot-Marie-Tooth (CMT) disease, one of the most common types of hereditary neuropathies, affects the motor and sensory nerves.
Hereditary neuropathies can have similar symptoms. Some of the most common symptoms include:
- Sensory symptoms: Pain, tingling, or numbness, often in the hands and feet.
- Motor symptoms: Muscle weakness and loss of mass (muscle atrophy), often in the feet and lower legs.
- Autonomic symptoms: Impaired sweating, or low blood pressure after standing up from sitting or lying down.
- Physical deformities: High foot arches, hammer-shaped toes, or a curved spine (scoliosis).
Hereditary neuropathy symptoms can range in intensity from mild to severe. In some cases, symptoms are so mild that the disorder goes undiagnosed and untreated for a long time.
Symptoms don’t always appear at birth or during childhood. They can appear during middle age or even later in life.
There are many different types of hereditary neuropathies. Sometimes, neuropathy is the distinguishing feature of the disease. This is the case with CMT. In other cases, neuropathy is part of a more widespread disorder.
More than 30 genes have been linked to hereditary neuropathies. Some genes haven’t yet been identified.
The most common types of hereditary neuropathy are described below:
Charcot-Marie-Tooth (CMT) disease
There are many genetic subtypes of CMT. CMT type 1A (CMT1A) is the most common. It affects approximately 20 percent of people who seek medical treatment for symptoms caused by an undiagnosed peripheral neuropathy.
Symptoms of CMT depend on the genetic subtype. The disorder can cause many of the symptoms listed above. Other symptoms can include:
- difficulty lifting the foot or holding it horizontally
- unsteady gait or balance
- poor hand coordination
At least four genes are involved in the transmission of CMT from parent to child. Children who have a parent with CMT have a 50 percent chance of inheriting the disease. A child can also develop CMT if both parents have recessive copies of the abnormal gene.
Hereditary neuropathy with liability to pressure palsies (HNPP)
People who have HNPP are extremely sensitive to pressure. They might have difficulty carrying a heavy shoulder bag, leaning on an elbow, or sitting on a chair. This pressure causes episodes of tingling, numbness, and loss of sensation in the affected area. Commonly affected areas include the:
These episodes can last up to several months.
Over time, repeated episodes can lead to permanent nerve damage and symptoms, such as muscle weakness and loss of sensation. People with HNPP may experience chronic pain, especially in the hands.
Having a family member, and especially a parent, who’s been diagnosed with a hereditary neuropathy is the most significant risk factor.
Some studies suggest that health conditions, such as type 2 diabetes and obesity, may increase your risk for certain hereditary neuropathies. More research needs to be done to understand the link between health conditions and hereditary neuropathies.
Your doctor might refer you to a nerve specialist, also known as a neurologist, to help diagnose this condition. You may need several tests before your doctor can reach a hereditary neuropathy diagnosis, including:
- Genetic testing. Genetic testing can be used to identify genetic abnormalities linked to hereditary neuropathies.
- Biopsies. A biopsy is a minimally invasive procedure that involves taking a tissue sample and looking at it under a microscope. This test can help identify nerve damage.
- Nerve conduction tests. Electromyography is used to help doctors understand your nerves’ ability to carry an electrical signal. This can help identify neuropathies. Nerve conduction tests can help identify the presence of a neuropathy, but they can’t be used to determine whether the neuropathy is hereditary or acquired.
- Neurological evaluations. These tests assess your reflexes, strength, posture, coordination, and muscle tone, as well as your ability to feel sensations.
Additional tests may be used to rule out other health conditions or identify injuries related to the neuropathy.
Hereditary neuropathy can be diagnosed at any age. However, symptoms for certain types are more likely to appear during infancy, childhood, or early adulthood.
There’s no cure for hereditary neuropathy. Instead, you’ll need ongoing treatment to manage your symptoms. Common treatments include:
- pain medication
- physical therapy
- corrective surgery
- therapeutic shoes, braces, and supports
If you have loss of sensation, your doctor might suggest certain safety measures to help you avoid hurting yourself.
Hereditary neuropathies can’t be prevented. Genetic counseling is available to parents who might be at risk of having a child with an inherited neuropathy.
If you’re experiencing symptoms of a hereditary neuropathy, you should make an appointment with your doctor right away. Early diagnosis can improve the long-term outlook. Keep a record of your symptoms to show to your doctor. If possible, identify whether neuropathy affects other members of your family.
The long-term outlook for people who have been diagnosed with hereditary neuropathy depends on the genes affected, as well as the type of neuropathy. Certain types of hereditary neuropathy progress more quickly than others.
In addition, hereditary neuropathy symptoms can be mild enough to go undiagnosed for a long time. Symptoms can also be severe and disabling.
If you have hereditary neuropathy, talk to your doctor about what to expect long term.