Neurology

Hereditary neuropathy with liability to pressure palsies is a disorder that affects peripheral nerves. These nerves connect the brain and spinal cord to muscles and sensory cells that detect touch, pain, and temperature. In people with this disorder, the peripheral nerves are unusually sensitive to pressure, such as the pressure that occurs when carrying heavy grocery bags, leaning on an elbow, or sitting without changing position, particularly with crossed legs. These activities would not normally cause sensation problems in people without the disorder.

Hereditary neuropathy with liability to pressure palsies is characterized by recurrent episodes of numbness, tingling, and loss of muscle function (palsy) in the region associated with the affected nerve, usually an arm, hand, leg, or foot.

The symptoms of hereditary neuropathy with liability to pressure palsies usually begin during adolescence or early adulthood but may develop anytime from childhood to late adulthood. Symptoms vary in severity; many people never realize they have the disorder, while some people experience prolonged disability. Hereditary neuropathy with liability to pressure palsies does not affect life expectancy.

Hereditary neuropathy with liability to pressure palsies is estimated to occur in 2 to 5 per 100,000 individuals.

Hereditary neuropathy with liability to pressure palsies is most commonly caused by the deletion of one copy of the PMP22 gene. This loss reduces the amount of PMP22 protein produced. Other PMP22 gene mutations that lead to a reduction of PMP22 protein can also cause the condition.

A shortage of PMP22 protein appears to make nerves less able to recover from compression, which impairs the transmission of nerve impulses, causing the signs and symptoms of hereditary neuropathy with liability to pressure palsies.

This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder.

Distal hereditary motor neuropathy, type V is a progressive disorder that affects nerve cells in the spinal cord. It results in muscle weakness and affects movement of the hands and feet.

The incidence of distal hereditary motor neuropathy, type V is unknown. Only a small number of cases have been reported.

The BSCL2 gene provides instructions for making a protein called seipin, whose function is unknown. Mutations in the BSCL2 gene likely alter the structure of seipin, causing it to fold into an incorrect 3-dimensional shape.

This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder.