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Last updated: 11/17/2023
Years published: 1991, 2004, 2013, 2016, 2019, 2023
NORD gratefully acknowledges Ingo Kurth, MD, Institute for Human Genetics and Genomic Medicine, University Hospital RWTH Aachen, Germany, for assistance in the preparation of this report.
Summary
Hereditary sensory and autonomic neuropathy type II (HSAN2) is a rare genetic disorder that usually begins in childhood, affecting the nerves that serve the lower legs and feet and the lower arms and hands. Symptoms often start with inflamed fingers or toes, especially around the nails. Numbness and tingling sensations in the hands and feet may also occur. Eventually, affected individuals lose feeling (sensation) in their hands and feet. This sensory loss is due to abnormal functioning of the sensory nerves that control responses to pain and temperature and may also affect the autonomic nervous system that controls other involuntary or automatic body processes. Chronic infection of the affected areas is common and worsens as ulcers form on the fingers or the soles of the hands and feet. The loss of sensation in the hands and feet often leads to neglect of the wounds. This can become serious, even leading to amputation in extreme cases if left untreated. In some patients, the motor nervous system may be affected, and spasticity of the arms and legs has been described. The disorder affects many of the bodyโs systems, is characterized by early onset (infancy or childhood) and follows an autosomal recessive pattern of inheritance. HSAN2 occurs due to pathogenic changes (variants or mutations) in specific genes. There are a few subtypes designated A through D, each one associated with a different gene.
Introduction
The hereditary sensory and autonomic neuropathies (HSAN), also known as the hereditary sensory neuropathies (HSN), include several similar but distinct inherited inborn or degenerative disorders of the nervous system that frequently progress to loss of feeling, especially in the hands and feet. Some of these disorders have several subtypes based upon the specific associated genes. Some types of HSAN are related to or identical with some forms of Charcot-Marie-Tooth disease, congenital insensitivity to pain (CIP) and others are related to or identical to familial dysautonomia (Riley-Day syndrome). The classification of the HSANs is complicated, and the experts do not always agree on it. Therefore, a molecular genetic classification should be preferred. Furthermore, HSANs are classified broadly as peripheral neuropathies or disorders of the peripheral nervous system, which predominantly encompasses all the nerves outside of the central nervous system (i.e., brain and spinal cord).
The symptoms of HSNs are highly variable, even among members of the same family. HSNs of various types may attack a single nerve (mononeuropathy) or many nerves simultaneously (polyneuropathy). The resulting symptoms may involve sensory, motor, reflex or blood vessel (vasomotor) function.
Although researchers have been able to establish HSANs as a distinct group of disorders with characteristic or โcoreโ symptoms, much about these disorders is not fully understood. Several factors including the small number of identified patients, the lack of large clinical studies and the possibility of other genes influencing the disorder prevent physicians from developing an accurate picture of associated symptoms and prognosis of all subtypes. Many of the reported individuals of HSAN2 are inconsistent in terms of symptomology and progression. This is partially caused by case reports that include cases that are not molecularly confirmed to be HSAN2. Consequently, it is important to note that affected individuals may not have all the symptoms discussed below. Parents should talk to their childrenโs physician and medical team about their specific case, the genetic origin of the disease, associated symptoms and overall prognosis.
HSAN2 is characterized by sensory loss of the distal portions of the legs. Distal refers to those areas that are farther from the center of the body and includes the lower arms and legs and the hands and feet. The legs and feet are more severely affected than the arms and hands. Onset is usually shortly after birth or during childhood.
Affected individuals may experience progressive numbness and tingling in their hands and feet. They may also experience reduced sensation to temperature, pain and touch. Eventually, affected individuals will be unable to distinguish between cold or warm stimuli and be unable to feel pain in the affected area. Because of the loss of sensation, affected individuals may develop chronic skin erosions, ulcers (open sores) or blisters that are slow to heal. These normally painful conditions do not hurt because of the loss of sensation. If unrecognized and left untreated, these painless injuries can progress to cause more serious complications such as recurrent infections. Eventually, affected individuals can develop infection of the surrounding bone (osteomyelitis), loss of bone and tissue in the fingers and toes (acroosteolysis), spontaneous, painless fractures and inflammation and damage to the surrounding joints (neuropathic arthropathy).
Most reports describe autonomic problems as less pronounced than sensory abnormalities in individuals with HSAN2. Many affected individuals have sweating abnormalities including episodes of excessive sweating (hyperhidrosis) or reduced sweating (hypohidrosis). Individuals can experience hyperhidrosis along with patchy areas of anhidrosis. Additional autonomic findings include backflow of the stomach contents into the esophagus (gastroesophageal reflux) and low blood pressure upon standing (postural hypotension) causing lightheadedness or dizziness.
Some individuals with HSAN2 exhibit self-mutilation, usually around the time of the eruption of primary teeth. Additional symptoms have been reported in some patients including dry scaly patches on the skin of the palms and soles (hyperkeratosis), diminished taste sensation, diminishment of certain reflexes and abnormal sideways curvature of the spine (scoliosis). Some infants and children may have difficulty swallowing. Sleep apnea, in which breathing slows or stops briefly during sleep, may also occur. Later in the course of the disorder, urinary incontinence or signs of spasticity may develop.
HSAN2 is caused by a change (variant or mutation) in one of four genes. HSAN2A is caused by variants in the WNK1 gene, HSAN2B is caused by variants in the FAM134B gene, lately renamed to RETREG1. HSAN2C is caused by variants in the KIF1A gene, HSAN2D is caused by variants in the SCN9A gene. Genes provide instructions for creating proteins that play a critical role in many functions of the body. When a variant of a gene occurs, the protein product may be altered, faulty, inefficient or absent. Depending upon the functions of the protein, this can affect many organ systems of the body.
HSAN2 is an autosomal recessive genetic condition. Recessive genetic disorders occur when an individual inherits a mutated gene from each parent. If an individual receives one normal gene and one mutated gene for the disease, the person will be a carrier for the disease, but usually will not show symptoms. The risk for two carrier parents to both pass the mutated gene and have an affected child is 25% with each pregnancy. The risk of having a child who is a carrier like the parents is 50% with each pregnancy. The chance for a child to receive normal genes from both parents is 25%. The risk is the same for males and females.
HSAN2 affects males and females in equal numbers. The exact incidence and prevalence are unknown. HSAN2 may go misdiagnosed or undiagnosed, making it difficult to determine the disorderโs true frequency in the general population.
A diagnosis of HSAN2 is based upon identification of characteristic symptoms, a detailed patient history, a thorough clinical evaluation and a variety of specialized tests. Early onset of sensory deficits and a family history consistent with autosomal recessive inheritance are indicative of HSAN2.
Clinical Testing and Workup
Electromyography (EMG) and particularly nerve conduction studies may be abnormal. During EMG, a thin electrode is inserted through the skin into an affected muscle. The electrode records the electrical activity of the muscles at rest and during contraction. This record, called an electromyogram, shows how well a muscle responds to the nerves and can determine whether muscle weakness is caused by the muscles themselves or by the nerves that control the muscles. Nerve conduction studies, which measure the speed of conduction and amplitude of an electrical impulse through a nerve, may be reduced in individuals with HSAN2.
Surgical removal and microscopic examination (biopsy) of affected nerve fibers / skin may be used to aid in the diagnosis of HSAN2 by revealing characteristic changes to nerves, however, molecular genetic testing is preferred.
An axonal flare test is sometimes used to aid in diagnosing HSAN2. During this test, a small amount of diluted histamine is injected underneath the skin. Histamine is a chemical compound produced by the body that helps the immune system and acts as a neurotransmitter (a chemical that modifies, amplifies or transmits nerve impulses from one nerve cell to another). An injection of histamine causes a distinctive skin eruption around the site of injection. In affected individuals, the skin eruption is different and may support the diagnosis of HSAN2. However, this test may be normal.
Molecular genetic testing can confirm a diagnosis. Molecular genetic testing can detect variants in the specific genes known to cause HSAN2.
Treatment
The treatment of HSAN2 is directed toward the specific symptoms that are apparent in each individual. Treatment may require the coordinated efforts of a team of specialists. Pediatricians, orthopedists, orthopedic surgeons, dermatologists, physiotherapists and other healthcare professionals may need to plan an affected childโs treatment systematically and comprehensively.
Genetic counseling is recommended for affected individuals and their families.
Prompt recognition and treatment of wounds on affected areas (e.g., the feet) is critically important. Ulceration of the feet of individuals with HSAN2 is extremely similar to ulcers found on the feet of individuals with diabetic neuropathy. Therefore, the treatment of foot ulcerations and infections may follow similar guidelines. Such treatment can include medical removal of diseased skin and tissue (debridement), applying medications and dressing to the wound, and keeping the wound clean and bandaged. Antibiotics may be used to treat infection. Affected individuals should receive instruction on proper care of their feet including avoiding risk factors for developing foot ulceration such as removing sources of pressure (e.g., shoes with pressure points). It is recommended that affected individuals receive routine foot care from a diabetic clinic or a podiatrist familiar with the treatment of diabetic foot ulcers.
Additional treatment is symptomatic and supportive.
A group of researchers in Germany is interested in HSAN disorders and offers genetic testing in a diagnostic setting or on a research basis for individuals meeting the criteria for a diagnosis of HSAN. For more information, contact:
Prof. Dr. med. Ingo Kurth
Director
Institute of Human Genetics and Genomic Medicine
University RWTH Aachen
Pauwelsstr. 30
52074 AachenGermany
Tel. +49-241-8080178
Fax +49-241-8082580
[email protected]
https://www.humangenetik.ukaachen.de
1st EJP RD Joint Transnational Call for Rare Diseases Research Project (JTC 2019)
Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.
For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:
Toll-free: (800) 411-1222
TTY: (866) 411-1010
Email: [email protected]
Some current clinical trials also are posted on the following page on the NORD website:
https://rarediseases.org/for-patients-and-families/information-resources/info-clinical-trials-and-research-studies/
For information about clinical trials sponsored by private sources, in the main, contact:
www.centerwatch.com
For more information about clinical trials conducted in Europe, contact: https://www.clinicaltrialsregister.eu/
TEXTBOOKS
De Jonghe P, Kuhlenbaumer G. Hereditary Sensory and Autonomic Neuropathies (HSAN). In: Hereditary Peripheral Neuropathies, Kuhlenbaumer G, Stogbauer F, Ringelstein EB, Young P, eds. 2005 Springer, New York, NY. pp. 157-170.
Mandler S, Pearl P. Hereditary Sensory Neuropathy Type II. In: NORD Guide to Rare Disorders. Lippincott Williams & Wilkins. Philadelphia, PA. 2003:571.
JOURNAL ARTICLES
Lischka A, Lassuthova P, รakar A, Record CJ, Van Lent J, Baets J, Dohrn MF, Senderek J, Lampert A, Bennett DL, Wood JN, Timmerman V, Hornemann T, Auer-Grumbach M, Parman Y, Hรผbner CA, Elbracht M, Eggermann K, Geoffrey Woods C, Cox JJ, Reilly MM, Kurth I. Genetic pain loss disorders. Nat Rev Dis Primers. 2022 Jun 16;8(1):41. doi: 10.1038/s41572-022-00365
Chen YC, Auer-Grumbach M, Matsukawa S, et al. Transcriptional regulator PRDM12 is essential for human pain perception [published correction appears in Nat Genet. 2015 Aug;47(8):962]. Nat Genet. 2015;47(7):803-808. doi:10.1038/ng.3308
Kornak U, Mademan I, Schinke M, et al. Sensory neuropathy with bone destruction due to a mutation in the membrane-shaping atlastin GTPase 3. Brain. 2014;137(Pt 3):683-692. doi:10.1093/brain/awt357 https://brain.oxfordjournals.org/content/brain/137/3/683.full.pdf
Bercier V, Brustein E, Liao M, et al. WNK1/HSN2 mutation in human peripheral neuropathy deregulates KCC2 expression and posterior lateral line development in Zebrafish (Danio rerio). PLoS Genet. 2013;9:e1003124. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3536653/
Leipold E, Liebmann L, Korenke GC, Heinrich T, Giesselmann S, Baets J, Ebbinghaus M, Goral RO, Stรถdberg T, Hennings JC, Bergmann M, Altmรผller J, Thiele H, Wetzel A, Nรผrnberg P, Timmerman V, De Jonghe P, Blum R, Schaible HG, Weis J, Heinemann SH, Hรผbner CA, Kurth I. A de novo gain-of-function mutation in SCN11A causes loss of pain perception. Nat Genet. 2013;45:1399โ 404. https://www.ncbi.nlm.nih.gov/pubmed/24036948
Yuan J, Matsuura E, Higuchi Y, Hashiguchi A, Nakamura T, Nozuma S, Sakiyama Y, Yoshimura A, Izumo S, Takashima H. Hereditary sensory and autonomic neuropathy type IID cause by an SCN9A mutation. Neurology. 2013;80:1641โ9. https://www.ncbi.nlm.nih.gov/pubmed/23596073
Rotthier A, Baets J, Timmerman V, Janssens K. Mechanisms of disease in hereditary sensory and autonomic neuropathies. Nat Rev Neurol. 2012;8:73-85. https://www.ncbi.nlm.nih.gov/pubmed/22270030
Murphy SM Davidson GL, Brandner S, Houlden H, Reilly MM. Mutation in FAM134B causing severe hereditary sensory neuropathy. J Neurol Neurosurg Psychiatry. 2012;83:119-120. https://www.ncbi.nlm.nih.gov/pubmed/21115472
Riviere JB, Ramalingam S, Lavastre V, et al. KIF1A, an axonal transport of synaptic vesicles, is mutated in hereditary sensory and autonomic neuropathy type 2. Am J Hum Genet. 2011;89:219-230. https://www.ncbi.nlm.nih.gov/pubmed/21820098
Kurth I, Pamminger T, Hennings JC, et al. Mutations in FAM134B, encoding a newly identified Golgi protein, cause severe sensory and autonomic neuropathy. Nat Genet. 2009;41:1179-81. https://www.ncbi.nlm.nih.gov/pubmed/1983819
Rotthier A, Baets J, de Vriendt E, et al. Genes for hereditary sensory and autonomic neuropathies: a genotype-phenotype correlation. Brain. 2009;132:2699-2711. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2759337/
Shekarabi M, Girard N, Riviere JB, et al. Mutations in the nervous system-specific HSN2 exon of WNK1 cause hereditary sensory neuropathy type II. J Clin Invest. 2008;118:2496-2505. https://www.ncbi.nlm.nih.gov/pubmed/18521183
Axelrod FB, Gold-von Simson G. Hereditary sensory and autonomic neuropathies: types II, III, and IV. Orphanet J Rare Dis. 2007;2:39. Published 2007 Oct 3. doi:10.1186/1750-1172-2-39
Verhoeven K, Timmerman V, Mauko B, et al. Recent advances in hereditary sensory and autonomic neuropathies. Curr Opin Neurol. 2006;19:474-480. https://www.ncbi.nlm.nih.gov/pubmed/16969157
Lafreniere RG, MacDonald ML, Dube MP, et al. Identification of a novel gene (HSN2) causing hereditary sensory and autonomic neuropathy type II through the Study of Canadian Genetic Isolates. Am J Hum Genet. 2004;74:1064-1073. https://www.ncbi.nlm.nih.gov/pubmed/15060842
INTERNET
Kurth I. Hereditary Sensory and Autonomic Neuropathy Type II. 2010 Nov 23 [Updated 2021 Apr 1]. In: Adam MP, Feldman J, Mirzaa GM, et al., editors. GeneReviewsยฎ [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2023. Available from: https://www.ncbi.nlm.nih.gov/books/NBK49247/ Accessed Nov 6, 2023.
HSAN IIA. Online Mendelian Inheritance in Man (OMIM). Baltimore. MD: The Johns Hopkins University; Entry No:201300; Last Update: 10/19/2016. Available at: https://omim.org/entry/201300 Accessed Nov 6, 2023.
HSAN2B.Online Mendelian Inheritance in Man (OMIM). Baltimore. MD: The Johns Hopkins University; Entry No:613115; Last Update: 10/15/2021. Available at: https://omim.org/entry/613115 Accessed Nov 6, 2023.
HSN2C. Online Mendelian Inheritance in Man (OMIM). Baltimore. MD: The Johns Hopkins University; Entry No:614213; Last Update: 01/12/2018. Available at: https://omim.org/entry/614213 Accessed Nov 6, 2023.
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