Hereditary sensory neuropathy type IA
Hereditary sensory neuropathy type IA is a progressive condition characterized by nerve abnormalities in the legs and feet, leading to loss of sensation, muscle weakness, and a risk of slow-healing ulcers.
Overview
Hereditary sensory neuropathy type IA (HSAN IA) involves the gradual destruction of neurons. Symptoms typically emerge between adolescence and late adulthood and worsen over time, though life expectancy is generally normal with proper management.
Symptoms
- Sensory loss: Tingling (paresthesias), numbness, and a reduced ability to feel pain, heat, or cold in the legs and feet. Some individuals experience shooting pains.
- Physical complications: Open sores (ulcers) on the feet or hands and infections of the fingertips (whitlows). Because of reduced pain sensation, these are often slow to heal and may lead to amputation if untreated.
- Muscle weakness: Muscle wasting and weakness, particularly in the ankles, which may eventually require wheelchair assistance.
- Hearing loss: Sensorineural hearing loss may develop in middle to late adulthood.
Causes & Risk Factors
Mutations in the SPTLC1 gene cause this condition. This gene provides instructions for the serine palmitoyltransferase (SPT) enzyme. Mutations cause the enzyme to produce toxic deoxysphingoid bases, which accumulate and destroy nerve cells.
Inheritance
This condition is inherited in an autosomal dominant pattern, meaning one copy of the altered gene in each cell is sufficient to cause the disorder.