Sensory neurons lose the ability to transmit signals, while motor neurons has reduced ability to transmit signals.Genes related to Hereditary sensory and autonomic neuropathy Type 1:
Mutations in the SPTLC1 gene cause hereditary sensory neuropathy type 1. The SPTLC1 gene provides instructions for making one part (subunit) of an enzyme called serine palmitoyltransferase (SPT). The SPT enzyme is involved in making certain fats called sphingolipids. Sphingolipids are important components of cell membranes and play a role in many cell functions. SPTLC1 gene mutations reduce the amount of SPTLC1 subunit that is produced and result in an SPT enzyme with decreased function. A lack of functional SPT enzyme leads to a decrease in sphingolipid production and a harmful buildup of certain byproducts. Sphingolipids are found in myelin, which is the covering that protects nerves and promotes the efficient transmission of nerve impulses. A decrease in sphingolipids disrupts the formation of myelin, causing nerve cells to become less efficient and eventually die. When sphingolipids are not made, an accumulation of toxic byproducts can also lead to nerve cell death. This gradual destruction of nerve cells results in loss of sensation and muscle weakness in people with hereditary sensory neuropathy type 1. Type 2, Congenital sensory neuropathy
Hereditary sensory and autonomic neuropathy type II (HSAN2) is a condition that primarily affects the sensory nerve cells (sensory neurons) which transmit information about sensations such as pain, temperature, and touch. These sensations are impaired in people with HSAN2.
Hereditary sensory and autonomic neuropathy (HSAN) or hereditary sensory neuropathy (HSN) is a condition used to describe any of the types of this disease which inhibit sensation. They are less common than Charcot-Marie-Tooth disease. Classification
Eight different clinical entities have been described under hereditary sensory and autonomic neuropathies – all characterized by progressive loss of function that predominantly affects the peripheral sensory nerves. Their incidence has been estimated to be about 1 in 250,000. Type 1
Hereditary sensory neuropathy type 1 is a condition characterized by nerve abnormalities in the legs and feet (peripheral neuropathy). Many people with this condition have tingling, weakness, and a reduced ability to feel pain and sense hot and cold. Some affected individuals do not lose sensation, but instead feel shooting pains in their legs and feet. As the disorder progresses, the sensory abnormalities can affect the hands, arms, shoulders, and abdomen. Affected individuals may also experience muscle wasting and weakness as they get older, but this varies widely within families. Affected individuals typically get open sores (ulcers) on their feet or hands or infections of the soft tissue of the fingertips (whitlows) that are slow to heal. Because affected individuals cannot feel the pain of these sores, they may not seek treatment right away. Without treatment, the ulcers can become infected and may require amputation of the surrounding area. Albeit rarely, people with hereditary sensory neuropathy type 1 may develop hearing loss caused by abnormalities of the inner ear (sensorineural hearing loss).