Arthropathy-related pain in a patient with congenital impairment of pain sensation due to hereditary sensory and autonomic neuropathy type II with a rare mutation in the WNK1/HSN2 gene: a case report

Expression pattern analysis and characterization of the hereditary sensory and autonomic neuropathy 2 A (HSAN2A) gene with no lysine kinase (WNK1) in human dorsal root ganglion

Inherited painless neuropathies arise due to genetic insults that either block the normal signaling of or destroy the sensory afferent neurons in the dorsal root ganglion (DRG) responsible for transducing noxious stimuli. Complete loss of these neurons leads to profound insensitivity to all sensory modalities including pain. Hereditary sensory and autonomic neuropathy type 2 (HSNAII) is a rare genetic neuropathy characterized by a progressive distal early onset sensory loss. This syndrome is caused by autosomal recessive mutations in the with-no-lysine protein kinase 1 (WNK1) serine-threonine kinase gene. Of interest, disease-associated mutations are found in the large exon, termed "HSN2," which encodes a 498 amino acid domain C-terminal to the kinase domain. These mutations lead to truncation of the HSN2-containing proteins through the addition of an early stop codon (nonsense mutation) leading to loss of the C-terminal domains of this large protein. The present study evaluates the transcripts, gene structure, and protein structure of HSN2-containing WNK1 splice variants in DRG and spinal cord in order to establish the basal expression patterns of WNK1 and HSN2-containing WNK1 splice variants using multiplex fluorescent situ hybridization. We hypothesized that these transcripts would be enriched in pain-sensing DRG neurons, and, potentially, that enrichment in nociceptive neurons was responsible for the painless phenotypes observed. However, our in-depth analyses revealed that the HSN2-WNK1 splice variants were ubiquitously expressed but were not enriched in tachykinin 1-expressing C-fiber neurons, a class of neurons with a highly nociceptive character. We subsequently identified other subpopulations of DRG neurons with higher levels of HSN2-WNK1 expression, including mechanosensory large fibers. These data are inconsistent with the hypothesis that this transcript is enriched in nociceptive fibers, and instead suggest it may be related to general axon maintenance, or that nociceptive fibers are more sensitive to the genetic insult. These findings clarify the molecular and cellular expression pattern of this painless neuropathy gene in human tissue.

A rare case of hereditary sensory and autonomic neuropathy type II

We describe the follow-up of a 29-year-old man diagnosed with hereditary sensory and autonomic neuropathy type II, including the different complications that presented since his childhood. Despite efforts to maintain an optimal quality of life, the lack of an early diagnosis led to an unfavorable prognosis and life condition.

Hereditary Sensory and Autonomic Neuropathy Type II in a Female Child with Multiple Orthopaedic Ailments: Diagnosis and Operative Management

Hereditary Sensory and Autonomic Neuropathy (HSAN) Type II is an autosomal recessive genetic disease which presents predominantly with sensory neuropathy and neuropathic ulcers. HSAN Type II is a rare disease, and in the few cases that have been reported, the focus has been on identifying genetic markers of the disease. Orthopaedic conditions may be a major presentation of the disease, and the prevention of superficial trauma and foot care is the only definitive management.