SNP Shot: Genomic Insights

Hereditary neuropathy with liability to pressure palsies (HNPP) is a condition affecting the peripheral nerves. These nerves are responsible for transmitting signals between the brain and spinal cord and the body's muscles and sensory receptors for touch, pain, and temperature. Individuals with HNPP experience heightened sensitivity in their peripheral nerves to pressure. Common activities like carrying groceries, leaning on an elbow, or prolonged sitting, especially with crossed legs, can trigger issues, unlike in individuals without the disorder.

HNPP is defined by recurring episodes of numbness, tingling, and muscle weakness (palsy) affecting the area served by the compressed nerve, typically in an arm, hand, leg, or foot. While episodes can range in duration from minutes to months, full recovery is typical. However, repeated occurrences can lead to permanent muscle weakness or sensory loss. Limb pain, especially in the hands, is also a common feature of HNPP.

These pressure palsy episodes arise from compression of a single nerve, and any peripheral nerve can be affected. Although episodes are recurrent, they don't necessarily involve the same nerve each time. Frequently affected sites are nerves in the wrists, elbows, and knees. Fingers, shoulders, hands, feet, and the scalp may also be involved. A common complication in HNPP is carpal tunnel syndrome, where the median nerve in the wrist is compressed, causing numbness, tingling, and weakness in the hand and fingers. Hand episodes can hinder fine motor skills like writing, opening jars, and buttoning clothes. Nerve compression at the knee can result in foot drop, impairing walking, stair climbing, and driving.

The onset of HNPP symptoms usually occurs during adolescence or early adulthood, but it can appear at any age from childhood through late adulthood. The severity of symptoms varies considerably; some individuals are unaware they have the disorder, while others experience long-term disability. HNPP does not impact lifespan.

Inheritance:

HNPP follows an autosomal dominant inheritance pattern. This means that only one copy of the mutated gene in each cell is enough to cause the condition.