Hereditary sensory and autonomic neuropathy
Encyclopedia
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
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(HMSN 2B).
Type 1 is transmitted as autosomal dominant trait and is characterized by a sensory deficit in the distal portion of the lower extremities, chronic perforating ulcerations of the feet and progressive destruction of underlying bones. Sweating abnormalities occur but other autonomic features are not found in this type. Symptoms appear in late childhood on early adolescence with trophic ulcers as pain sensation is affected more. Many patients have accompanying nerve deafness and atrophy of the peroneal muscles. Histopathologic examination reveals a marked reduction in the number of unmyelinated fibers. Motor nerve conduction velocities are normal, but the sensory nerve action potentials are absent.
of the distal phalanges is common and so is neuropathic joint degeneration. The NCV
shows reduced or absent sensory nerve action potentials and nerve biopsy shows total loss of myelinated fibers and reduced numbers of unmyelinated fibers. It is inherited as an autosomal recessive condition.
shows motor and sensory nerve action potentials to be normal. The histopathology of peripheral nerve biopsy reveals absent small unmyelinated fibers and mitochondria are abnormally enlarged.
They are less common than Charcot-Marie-Tooth disease
Charcot-Marie-Tooth disease
Charcot–Marie–Tooth disease- , known also as Morbus Charcot-Marie-Tooth, Charcot-Marie-Tooth neuropathy, hereditary motor and sensory neuropathy , hereditary sensorimotor neuropathy , or peroneal muscular atrophy, is an inherited disorder of nerves that takes different forms...
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Classification
Five 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 25,000.Type 1
Type 1 is the most common of the hereditary sensory and autonomic neuropathies (HSAN). Current names are: hereditary sensory neuropathy type I (HSN I), hereditary sensory and autonomic neuropathy type I (HSAN I). Historical names include: Hereditary sensory radicular neuropathy, ulcero-mutilating neuropathy, thevenard syndrome, familial trophoneurosis, mal perforant du pied, and familial syringomyelia. Sub-type 1C is also currently known as Charcot-Marie-Tooth type 2B syndromeCharcot-Marie-Tooth disease
Charcot–Marie–Tooth disease- , known also as Morbus Charcot-Marie-Tooth, Charcot-Marie-Tooth neuropathy, hereditary motor and sensory neuropathy , hereditary sensorimotor neuropathy , or peroneal muscular atrophy, is an inherited disorder of nerves that takes different forms...
(HMSN 2B).
Type 1 is transmitted as autosomal dominant trait and is characterized by a sensory deficit in the distal portion of the lower extremities, chronic perforating ulcerations of the feet and progressive destruction of underlying bones. Sweating abnormalities occur but other autonomic features are not found in this type. Symptoms appear in late childhood on early adolescence with trophic ulcers as pain sensation is affected more. Many patients have accompanying nerve deafness and atrophy of the peroneal muscles. Histopathologic examination reveals a marked reduction in the number of unmyelinated fibers. Motor nerve conduction velocities are normal, but the sensory nerve action potentials are absent.
Type 2, Congenital sensory neuropathy
Type 2, congenital sensory neuropathy (also historically known as Morvan's disease), is characterized by onset of symptoms in early infancy or childhood. Upper & lower extremities are affected with chronic ulcerations and multiple injuries to fingers and feet. Pain sensation is affected predominantly and deep tendon reflexes are reduced. AutoamputationAutoamputation
Autoamputation is the spontaneous detachment of an appendage from the body. This is not to be confused with self-amputation....
of the distal phalanges is common and so is neuropathic joint degeneration. The NCV
Nerve conduction velocity
Nerve conduction velocity is the speed at which an electrochemical signal propagates down a neural pathway. Many things can affect this, including axon diameter, myelination, the internal resistance of the axon, and temperature. Nerve conduction velocity differs from species to species, and to a...
shows reduced or absent sensory nerve action potentials and nerve biopsy shows total loss of myelinated fibers and reduced numbers of unmyelinated fibers. It is inherited as an autosomal recessive condition.
Type 3, Familial dysautonomia
Type 3, familial dysautonomia (FD) or Riley-Day syndrome, is an autosomal recessive disorder seen predominantly in Jews of eastern European descent. Patients present with sensory and autonomic disturbances. Newborns have absent or weak suck reflex, hypotonia and hypothermia. Retarded physical development, poor temperature and motor in coordination are seen in early childhood. Other features include reduced or absent tears, depressed deep tendon reflexes, absent corneal reflex, postural hypotension and relative indifference to pain. Scoliosis is frequent. Intelligence remains normal. Many patients die in infancy and childhood. Lack of flare with intradermal histamine is seen. Histopathology of peripheral nerve shows reduced number of myelinated and non-myelinated axons. The catecholamine endings are absent.Type 4, Congenital insensitivity to pain with anhidrosis
Type 4, congenital insensitivity to pain with anhidrosis (CIPA), is an autosomal recessive condition and affected infants present with episodes of hyperthermia unrelated to environmental temperature, anhidrosis and insensitivity to pain. Palmar skin is thickened and charcot joints are commonly present. NCVNerve conduction velocity
Nerve conduction velocity is the speed at which an electrochemical signal propagates down a neural pathway. Many things can affect this, including axon diameter, myelination, the internal resistance of the axon, and temperature. Nerve conduction velocity differs from species to species, and to a...
shows motor and sensory nerve action potentials to be normal. The histopathology of peripheral nerve biopsy reveals absent small unmyelinated fibers and mitochondria are abnormally enlarged.
Type 5, Congenital insensitivity to pain with partial anhidrosis
Type 5, congenital insensitivity to pain with partial anhidrosis, also manifests with congenital insensitivity to pain & anhidrosis. There is a selective absence of small myelinated fibers differentiating it from Type IV (CIPA).Associated genes
| Type | Sub-type | Gene | Locus >- | rowspan="4" | HSAN 1 |
1A | SPTLC1 SPTLC1 Serine palmitoyltransferase, long chain base subunit 1, also known as SPTLC1, is a protein which in humans is encoded by the SPTLC1 gene.... |
>- | unknown (OMIM 608088) | >- | RAB7A RAB7A Ras-related protein Rab-7a is a protein that in humans is encoded by the RAB7A gene.Various mutations of RAB7A are associated with Hereditary sensory neuropathy type 1C , also known as Charcot-Marie-Tooth syndrome type 2B .... |
>- | unknown | unknown >- | colspan="2" | HSAN 2 |
HSN2 HSN2 Hereditary sensory neuropathy, type II also known as HSN2 is a protein which in humans in encoded by the HSN2. It is a single-exon ORF, and a nervous system-specific exon of the WNK1 gene... |
>- | IKBKAP IKBKAP IKBKAP is a human gene that provides instructions to make the IKAP protein, which is found in a variety of cells throughout the body, including brain cells... |
>- | NTRK1 | >- | NGFß | >- | NTRK1 |