Hereditary Sensory Neuropathy Research Articles

Involvement of sphingosine-1-phosphate receptor 1 in pain insensitivity in a BTBR mouse model of autism spectrum disorder

BackgroundAbnormal sensory perception, particularly pain insensitivity (PAI), is a typical symptom of autism spectrum disorder (ASD). Despite the role of myelin metabolism in the regulation of pain perception, the mechanisms underlying ASD-related PAI remain unclear.MethodsThe pain-associated gene sphingosine-1-phosphate receptor 1 (S1PR1) was identified in ASD samples through bioinformatics analysis. Its expression in the dorsal root ganglion (DRG) tissues of BTBR ASD model mice was validated using RNA-seq, western blot, RT-qPCR, and immunofluorescence. Pain thresholds were assessed using the von Frey and Hargreaves tests. Patch-clamp techniques measured KCNQ/M channel activity and neuronal action potentials. The expression of S1PR1, KCNQ/M, mitogen-activated protein kinase (MAPK), and cyclic AMP/protein kinase A (cAMP/PKA) signaling proteins was analyzed before and after inhibiting the S1P-S1PR1-KCNQ/M pathway via western blot and RT-qPCR.ResultsThrough integrated transcriptomic analysis of ASD samples, we identified the upregulated gene S1PR1, which is associated with sphingolipid metabolism and linked to pain perception, and confirmed its role in the BTBR mouse model of ASD. This mechanism involves the regulation of KCNQ/M channels in DRG neurons. The enhanced activity of KCNQ/M channels and the decreased action potentials in small and medium DRG neurons were correlated with PAI in a BTBR mouse model of ASD. Inhibition of the S1P/S1PR1 pathway rescued baseline insensitivity to pain by suppressing KCNQ/M channels in DRG neurons, mediated through the MAPK and cAMP/PKA pathways. Investigating the modulation and underlying mechanisms of the non-opioid pathway involving S1PR1 will provide new insights into clinical targeted interventions for PAI in ASD.ConclusionsS1PR1 may contribute to PAI in the PNS in ASD. The mechanism involves KCNQ/M channels and the MAPK and cAMP/PKA signaling pathways. Targeting S1PR1 in the PNS could offer novel therapeutic strategies for the intervention of pain dysesthesias in individuals with ASD.

A Novel Pathogenic Mutation in WNK1 Gene Causing HSAN Type II in Three Siblings.

Hereditary sensory and autonomic neuropathy (HSAN) is a rare genetic disorder that primarily affects the peripheral nervous system, leading to a progressive loss of the ability to perceive pain, temperature, and touch. This condition can result in severe complications, including injuries and infections due to the inability to feel pain. HSAN is classified into nine types, with types I and VII exhibiting autosomal dominant inheritance, while the others follow an autosomal recessive pattern. In this study, we examined three affected brothers of Turkish Azeri descent, aged 20, 23, and 25 years. They presented symptoms such as a lack of temperature and pain sensation, frequent wounds and infections, self-harm, and hyperkeratosis. To identify the genetic cause of their condition, whole-exome sequencing (WES) was performed, followed by Sanger sequencing to confirm the findings. The results revealed a homozygous likely pathogenic nonsense mutation, c.2971C > T (p.Arg991Ter), in exon 9 of the WNK1 gene. This mutation results in the truncation of three isoforms of the WNK1 protein, which are essential for pain perception. This discovery enhances our understanding of HSAN and highlights the importance of genetic testing for accurate diagnosis and future screening.

Brief communication participation in social activities of six individuals with advanced-stage hereditary motor sensory neuropathy with proximal dominant involvement (HMSN-P)

The intractable neurological disease HMSN-P (hereditary motor and sensory neuropathy with proximal dominant involvement) includes four-limb paralysis and resembles amyotrophic lateral sclerosis (ALS). Although the long-term employment and social activities of individuals with severe neurological diseases have increased with improvements in medical/welfare services, those of individuals with HMSN-P have not been reported. We analyzed the long-term outcomes of six individuals with advanced-stage HMSN-P treated in 2018–2023; one exhibited proximal dominant quadriplegia in 2018 and was using an electric wheelchair with full assistance. He had continued to attend Sanshin concerts for 5 years and organized a music festival for the local handicapped population. The other patients similarly exhibited quadriplegia; three were using electric wheelchairs with full assistance, and two were using pushchairs. Four attended music festivals for the handicapped, and all have completed 20–35 years' continuous employment, attended public meetings about HMSN-P, and actively participated in the meetings' discussions.

Congenital Insensitivity to Pain With Anhidrosis Is Associated With Harlequin Color Change: A Survey Study.

Congenital insensitivity to pain with anhidrosis (CIPA), also known as hereditary sensory and autonomic neuropathy (HSAN) type IV, is an extremely rare autosomal recessive congenital condition characterized by the loss of sensation to pain and absence of sweating with one case report linking this with harlequin color change. To explore the relationship further, we developed a survey using the Research Electronic Data Capture software and distributed it to families and others with close relationships and knowledge of patients with CIPA. Our results indicate that harlequin color change, characterized by unilateral flushing of the face and/or body, was significant and noted by all respondents as being present early in the condition appearing around the same time as first symptoms and around or before diagnosis of CIPA. Future clinicians should be aware of this dermatological phenomenon and its potential association with CIPA patients, especially during early disease manifestation where diagnosis can be difficult.

Expanding the genetic spectrum of hereditary motor sensory neuropathies in Pakistan

BackgroundHereditary motor and sensory neuropathy (HMSN) refers to a group of inherited progressive peripheral neuropathies characterized by reduced nerve conduction velocity with chronic segmental demyelination and/or axonal degeneration. HMSN is highly clinically and genetically heterogeneous with multiple inheritance patterns and phenotypic overlap with other inherited neuropathies and neurodegenerative diseases. Due to this high complexity and genetic heterogeneity, this study aimed to elucidate the genetic causes of HMSN in Pakistani families using Whole Exome Sequencing (WES) for variant identification and Sanger sequencing for validation and segregation analysis, facilitating accurate clinical diagnosis.MethodsFamilies from Khyber Pakhtunkhwa with at least two members showing HMSN symptoms, who had not previously undergone genetic analysis, were included. Referrals for genetic investigations were based on clinical features suggestive of HMSN by local neurologists. WES was performed on affected individuals from each family, with Sanger sequencing used to validate and analyze the segregation of identified variants among family members. Clinical data including age of onset were assessed for variability among affected individuals, and the success rate of genetic diagnosis was compared with existing literature using proportional differences and Cohen’s h.ResultsWES identified homozygous pathogenic variants in GDAP1 (c.310 + 4 A > G, p.?), SETX (c.5948_5949del, p.(Asn1984Profs*30), IGHMBP2 (c.1591 C > A, p.(Pro531Thr) and NARS1 (c.1633 C > T, p.(Arg545Cys) as causative for HMSN in five out of nine families, consistent with an autosomal recessive inheritance pattern. Additionally, in families with HMSN, a SETX variant was found to cause cerebellar ataxia, while a NARS1 variant was linked to intellectual disability. Based on American College of Medical Genetics and Genomics criteria, the GDAP1 variant is classified as a variant of uncertain significance, while variants in SETX and IGHMBP2 are classified as pathogenic, and the NARS1 variant is classified as likely pathogenic. The age of onset ranged from 1 to 15 years (Mean = 5.13, SD = 3.61), and a genetic diagnosis was achieved in 55.56% of families with HMSN, with small effect sizes compared to previous studies.ConclusionsThis study expands the molecular genetic spectrum of HMSN and HMSN plus type neuropathies in Pakistan and facilitates accurate diagnosis, genetic counseling, and clinical management for affected families.

A RETREG1 variant is associated with hereditary sensory and autonomic neuropathy with acral self-mutilation in purebred German Spitz.

Hereditary sensory and autonomic neuropathies (HSAN) represent a group of genetic diseases affecting the peripheral nervous system. In humans, at least 16 loci have been associated with the disorder but do not explain the disease origin of all patients. In dogs, similar conditions have been documented for decades in various breeds with a severe impact on life quality and are often referred to as acral mutilation syndrome (AMS). Causal variants in three genes have been identified to date, suggesting larger genetic heterogeneity in the dog population. Our aim was to explain the genetic etiology of an early-onset HSAN/AMS in a purebred German Spitz. The affected dog showed progressive loss of pain sensation in the distal extremities, which led to intense licking, biting, and self-mutilation of digits and paw pads. Whole-genome sequencing identified a single candidate causal variant on chromosome 4 in the RETREG1 gene (c.656C>T, p.Pro219Leu). This missense variant was previously recognized as deleterious in a mixed breed dog family with similar clinical signs. Haplotype analyses and targeted genotyping revealed a likely German Spitz ancestry of these mixed breed dogs. Further screening of an extensive cohort of ~900 000 dogs of various breeds hinted at the variant allele origin in the German Spitz breed. Disruption of RETREG1 inhibits endoplasmic reticulum turnover and leads to neuron degeneration. Our findings provide evidence that this variant underlies the recessive form of HSAN/AMS in the German Spitz and support the use of whole-genome sequencing-based veterinary precision medicine for early diagnosis and prevention via a genetic test.

Atypical Presentation of Congenital Insensitivity to Pain With Anhidrosis Leading to Diagnostic Odyssey.

Congenital insensitivity to pain with anhidrosis (CIPA) (OMIM 256800) is a rare autosomal-recessive condition, also known as hereditary sensory and autonomic neuropathy type IV (HSAN-IV). The most commonly reported features include anhidrosis, intellectual disability, self-mutilation, febrile episodes, impaired temperature perception, recurrent infections and/or autonomic nervous system impairment. Major joint destruction and joint deformity known as Charcot (neuropathic) joints are also seen in CIPA patients attributed to insensitivity to joint pain. We present a case of a 46-year-old female affected with CIPA with a known NTRK1 variant and previously unidentified variant. Minigene reporter constructs were generated encompassing the exon 8 to exon 13 of the NTRK1 gene using the reference sequence and one harboring c.1483 + 5G > A variant identified in our proband. Minigene constructs were transfected into HEK293T cells, and the transcript was analysed for splicing to evaluate the effect of this variant in splicing. The patient (46-year-old female) exhibited right ankle joint deformity around 5 years of age. Patient also experienced lumbar compression and knee damage in adulthood. She had undergone a significant number of evaluations without clear diagnosis. Her presentation lacked many of the common clinical presentations of CIPA, and therefore, the focus of her evaluation was directed towards her unexplained joint deformities. Exome sequencing revealed a known pathogenic variant in NTRK1 (c.851-33T > A:p.? [Intron 7]) and a novel NTRK1 variant (c.1483 + 5G > A:p.? [Intron 11]), which was later re-classified as likely pathogenic. The patient was started on a biologic disease-modifying anti-rheumatic medication (bDMARD) due to a possible inflammatory etiology of her joint deformity. Molecular diagnosis allowed for modification of her treatment and surveillance strategies. Our minigene splicing assay demonstrated that the presence of the c.1483 + 5G > A variant has a negative effect on splicing, supporting the pathogenicity of this novel variant.

479P Hereditary sensory & autonomic neuropathy type 2A (HSAN2A): insights into genetic aetiology and variant classification

479P Hereditary sensory & autonomic neuropathy type 2A (HSAN2A): insights into genetic aetiology and variant classification

109P Preserve sense by antisense – a novel allele-specific antisense oligonucleotide therapy for SPTLC1-related hereditary sensory neuropathy

109P Preserve sense by antisense – a novel allele-specific antisense oligonucleotide therapy for SPTLC1-related hereditary sensory neuropathy

Clinical markers of Charcot-Marie-Tooth disease (own experience)

Charcot-Marie-Tooth disease is also called hereditary motor and sensory neuropathy. It is a genetically determined disease that has different variants of inheritance whose substratum is neuromuscular disorders. It may begin during childhood or later in life. Scientists have identified and described more than thirty genetic mutations that form an individual unique passport of violations of the sequence of a group of organic compounds or nucleotides in nucleic acid molecules. There are autosomal dominant, autosomal recessive and X-linked types of genetic inheritance of Charcot-Marie-Tooth disease. This pathology was first described in 1886 and affects about 10 to 40 per 100,000 population. More than 15,000 cases of Charcot-Marie-Tooth disease have been registered in Ukraine. It should be noted that peripheral myelin protein 22 became the first described gene causing Charcot-Marie-Tooth disease. Autosomal dominant Charcot-Marie-Tooth type 1 is the most common form of the disease. When observing patients, a neurologist pays attention to gait disturbances (steppage gait), foot distortion (pes cavus), distal hypotrophy, decrease or absence of tendon and periosteal reflexes, weakness and loss of sensitivity in the distal parts of the limbs. Hypotrophic changes in the limbs are continuously progressive. As a result of muscle atrophy and foot deformity, high-arched feet and extension of the big toe (Friedreich’s foot) are formed. To date, no pathogenetically substantiated treatment exists for Charcot-Marie-Tooth disease, but a multi-vector approach to comprehensive rehabilitation measures creates the necessary conditions to effectively control the manifestations of the inevitable progression of this pathology.

Development of a Multiplexed Sphingolipids Method for Diagnosis of Inborn Errors of Ceramide Metabolism.

Sphingolipids play a crucial role in cellular functions and are essential components of cell membranes, signaling molecules, and lipid metabolism. In particular, ceramide is a key intermediate in sphingolipid metabolism and defects in ceramide metabolism can lead to various inborn errors of metabolism, making ceramides important targets for clinical screening and diagnosis. Detecting altered concentration patterns of sphingolipids is desirable for distinguishing related inborn errors of metabolism for diagnosis and treatment monitoring. We developed a liquid chromatography-tandem mass spectrometry method with a pathway-oriented approach to focus on sphingolipids involved in ceramide metabolism. A total of 47 sphingolipids bearing different head groups and side chains were targeted. Precision/reproducibility, linearity, and spike recovery extraction efficiency tests were performed on plasma and serum samples from confirmed cases of sphingolipidosis. Linearity of the method showed the coefficient of determination (r2) for all standards to be >0.99 with a slope of 1.00 ± 0.01. Intra- and interday reproducibility of standards spiked into plasma and serum revealed a coefficient of variation <20%. Spike and recovery assessment showed recovery values of 80%-120% for all standards. Altered levels of sphingolipids from patients with hereditary sensory and autonomic neuropathy caused by pathogenic variants in SPTLC2 and hypomyelinating leukodystrophy related to variants in DEGS1 were detected, in agreement with trends reported in earlier studies confirming the utility of this pathway-centric method. This method can serve as a useful tool to simultaneously monitor sphingolipids, enabling screening and diagnosis of inborn errors of ceramide metabolism.

Hereditary sensory autonomic neuropathy type VI in the age of genetic testing

AbstractBackgroundHereditary sensory and autonomic neuropathy type VI (HSAN VI) is a rare recessive genetic disorder caused by mutations in the human dystonin (DST) gene. We report a novel homozygous alternate transcript mutation in the DST gene causing a severe neonatal form of HSAN VI.Patient DescriptionThis baby boy was born with severe hypotonia, respiratory distress, dysmorphic features, and bilateral club feet. Imaging, karyotyping, Prader–Willi assay, spinal muscular atrophy genetic panel and myotonic dystrophy genetic panel were all negative. A comprehensive neuropathy panel detected a homozygous pathogenic variant in the DST gene—alternate transcript NM_015546.4:c.1357G&gt;A (p.Trp4525*). Nerve conduction studies revealed mixed axonal and demyelinating sensorimotor neuropathy, suggesting the possibility of motor involvement in severe forms of this rare condition. The infant ultimately developed sepsis and died from cardiorespiratory arrest. Neuropathological findings of focal and mild spinal nerve axonal degeneration were nonspecific.ConclusionCollective analysis of these patients would help to further characterize the spectrum of disease pathology and could provide insight into the neurophysiology and neuropathology of this rare condition.

Sensory-motor circuit is a therapeutic target for dystonia musculorum mice, a model of hereditary sensory and autonomic neuropathy 6.

Mutations in Dystonin (DST), which encodes cytoskeletal linker proteins, cause hereditary sensory and autonomic neuropathy 6 (HSAN-VI) in humans and the dystonia musculorum (dt) phenotype in mice; however, the neuronal circuit underlying the HSAN-VI and dt phenotype is unresolved. dt mice exhibit dystonic movements accompanied by the simultaneous contraction of agonist and antagonist muscles and postnatal lethality. Here, we identified the sensory-motor circuit as a major causative neural circuit using a gene trap system that enables neural circuit-selective inactivation and restoration of Dst by Cre-mediated recombination. Sensory neuron-selective Dst deletion led to motor impairment, degeneration of proprioceptive sensory neurons, and disruption of the sensory-motor circuit. Restoration of Dst expression in sensory neurons using Cre driver mice or a single postnatal injection of Cre-expressing adeno-associated virus ameliorated sensory degeneration and improved abnormal movements. These findings demonstrate that the sensory-motor circuit is involved in the movement disorders in dt mice and that the sensory circuit is a therapeutic target for HSAN-VI.

Fam134c and Fam134b shape axonal endoplasmic reticulum architecture in vivo

Endoplasmic reticulum (ER) remodeling is vital for cellular organization. ER-phagy, a selective autophagy targeting ER, plays an important role in maintaining ER morphology and function. The FAM134 protein family, including FAM134A, FAM134B, and FAM134C, mediates ER-phagy. While FAM134B mutations are linked to hereditary sensory and autonomic neuropathy in humans, the physiological role of the other FAM134 proteins remains unknown. To address this, we investigate the roles of FAM134 proteins using single and combined knockouts (KOs) in mice. Single KOs in young mice show no major phenotypes; however, combined Fam134b and Fam134c deletion (Fam134b/cdKO), but not the combination including Fam134a deletion, leads to rapid neuromuscular and somatosensory degeneration, resulting in premature death. Fam134b/cdKO mice show rapid loss of motor and sensory axons in the peripheral nervous system. Long axons from Fam134b/cdKO mice exhibit expanded tubular ER with a transverse ladder-like appearance, whereas no obvious abnormalities are present in cortical ER. Our study unveils the critical roles of FAM134C and FAM134B in the formation of tubular ER network in axons of both motor and sensory neurons.

Serine Palmitoyltransferase (SPT)-related Neurodegenerative and Neurodevelopmental Disorders.

Motor neuron diseases and peripheral neuropathies are heterogeneous groups of neurodegenerative disorders that manifest with distinct symptoms due to progressive dysfunction or loss of specific neuronal subpopulations during different stages of development. A few monogenic, neurodegenerative diseases associated with primary metabolic disruptions of sphingolipid biosynthesis have been recently discovered. Sphingolipids are a subclass of lipids that form critical building blocks of all cellular and subcellular organelle membranes including the membrane components of the nervous system cells. They are especially abundant within the lipid portion of myelin. In this review, we will focus on our current understanding of disease phenotypes in three monogenic, neuromuscular diseases associated with pathogenic variants in components of serine palmitoyltransferase, the first step in sphingolipid biosynthesis. These include hereditary sensory and autonomic neuropathy type 1 (HSAN1), a sensory predominant peripheral neuropathy, and two neurodegenerative disorders: juvenile amyotrophic lateral sclerosis affecting the upper and lower motor neurons with sparing of sensory neurons, and a complicated form of hereditary spastic paraplegia with selective involvement of the upper motor neurons and more broad CNS neurodegeneration. We will also review our current understanding of disease pathomechanisms, therapeutic approaches, and the unanswered questions to explore in future studies.

Functional and Molecular Characterization of New SPTLC1 Missense Variants in Patients with Hereditary Sensory and Autonomic Neuropathy Type 1 (HSAN1).

Hereditary sensory and autonomic neuropathy type 1 is an autosomal dominant neuropathy caused by the SPTLC1 or SPTLC2 variants. These variants modify the preferred substrate of serine palmitoyl transferase, responsible for the first step of de novo sphingolipids synthesis, leading to accumulation of cytotoxic deoxysphingolipids. Diagnosis of HSAN1 is based on clinical symptoms, mainly progressive loss of distal sensory keep, and genetic analysis. Aim: Identifying new SPTLC1 or SPTLC2 "gain-of-function" variants raises the question as to their pathogenicity. This work focused on characterizing six new SPTLC1 variants using in silico prediction tools, new meta-scores, 3D modeling, and functional testing to establish their pathogenicity. Methods: Variants from six patients with HSAN1 were studied. In silico, CADD and REVEL scores and the 3D modeling software MITZLI were used to characterize the pathogenic effect of the variants. Functional tests based on plasma sphingolipids quantification (total deoxysphinganine, ceramides, and dihydroceramides) were performed by tandem mass spectrometry. Results: In silico predictors did not provide very contrasting results when functional tests discriminated the different variants according to their impact on deoxysphinganine level or canonical sphingolipids synthesis. Two SPTLC1 variants were newly described as pathogenic: SPTLC1 NM_006415.4:c.998A>G and NM_006415.4:c.1015G>A. Discussion: The combination of the different tools provides arguments to establish the pathogenicity of these new variants. When available, functional testing remains the best option to establish the in vivo impact of a variant. Moreover, the comprehension of metabolic dysregulation offers opportunities to develop new therapeutic strategies for these genetic disorders.

A Young Man With Hereditary Motor And Sensory Neuropathy: A Rare Genetic Association

Hereditary motor and sensory neuropathies with early onset are uncommon conditions that include Dejerine-Sottas neuropathy, which begins in infancy, and congenital hypomyelinating neuropathy, which manifests in the early postnatal period. However, these two historically defined disease entities are only small parts of the clinical spectrum. It is well recognized that very early onset hereditary neuropathies are frequently caused by de novo dominant mutations in PMP22, MPZ, and EGR2. In addition, mutations in several other dominant and recessive genes for Charcot-Marie-Tooth disease may lead to similar phenotypes. A 20-year-old boy had complaints of weakness of both lower limbs for 1 year, followed by wasting and foot drop, which subsequently involved the upper limbs. Nerve conduction velocity and electromyography of both lower limbs revealed demyelinating sensory motor polyneuropathy. Histological examination of the sural nerve revealed a nerve trunk with perineural soft tissue, with the nerve bundles being irregular and separated by fibrous tissue bands. The later reveals small perivascular infiltration of chronic inflammatory cells, and no granuloma or AFB is seen. The genetic test of whole exome screening for heriditatory neuropathy showed pathogenic (PM2, PVS, PP5) with a gene impact of (NF2: c.363+1G&gt;T), which is a rare entity in our case study to consider the diagnosis despite negative family history. We highlight this rare disease in young man with a high index of clinical suspicion for its diagnosis. Bangladesh J Medicine 2024; 35: 101-105

A novel NTRK1 splice site variant causing congenital insensitivity to pain with anhidrosis in a Chinese family.

Congenital insensitivity to pain with anhidrosis (CIPA, OMIM #256800), also known as hereditary sensory and autonomic neuropathy type Ⅳ (HSAN-IV), is a rare autosomal recessive disorder characterized by recurrent episodic fevers, anhidrosis, insensitivity to noxious stimuli, self-mutilating behavior and intellectual disability. CIPA can be caused by the variants in NTRK1 gene, which encodes a high-affinity tyrosine kinase receptor for nerve growth factor. To ascertain the hereditary cause of a patient with CIPA accompanied by the additional symptoms of mild growth retardation, prone to fracture, underdeveloped nails of fingers and toes, irregular tooth alignment, enamel hypoplasia, postoperative wound healing difficulty, hand and limb deformity, and dislocation of hip joint, whole exome sequencing was used and revealed a compound heterozygous variant in NTRK1. DNA was extracted from peripheral blood samples of pediatric patients and their parents, and subjected to comprehensive analysis using whole-exome sequencing (WES), followed by verification of variant sites in the NTRK1 gene through Sanger sequencing. To elucidate the functional impact of the newly discovered variants, an in vitro experimental system was established. Splicing analysis was conducted using PCR and Sanger sequencing, while expression levels were assessed through qPCR and Western blot techniques. One hotspot variant c.851-33T>A(ClinVar ID: 21308) and a novel variant c.850 + 5G>A(ClinVar ID:3069176) was inherited from her father and mother, respectively, identified in the affected individuals. The c.850 + 5G>A variant in NTRK1 resulted in two forms of aberrant mRNA splicing: 13bp deletion (c.838_850del13, p. Val280Ser fs180) and 25bp deletion (826_850del25, p. Val276Ser fs180) in exon 7, both leading to a translational termination at a premature stop codon and forming a C-terminal truncated protein. The expression of two abnormal splicing isoforms was decreased both in the level of mRNA and protein. In conclusion, this study elucidated the genetic cause of a patient with CIPA and identified a novel variant c.850 + 5G>A in NTRK1, which broadened the and enriched the NTRK1 mutation spectrum.

A Continuum of Nerve Biopsies in Peripheral Neuropathy: A Clinicopathological Insight

Background: Peripheral neuropathy is a common neurological disease faced by the neurologists these days. The role of nerve biopsy is ambiguous and the dilemma to identify the underling etiology further adds to the uncertainty. However, ruling out certain etiological causes and confirming specific diagnosis still mandates the procedure. Aim: The aim of the study is to evaluate the contribution of nerve biopsy in peripheral neuropathies and study the histomorphological spectrum of these biopsies. Material and methods: A retrospective 2-year review of 54 nerve biopsies received in the Department of Pathology was performed at a tertiary care centre. Results: A total of 54 nerve biopsies were reviewed during the study period, of which, 6 biopsies (11%) were considered inadequate. Biopsies were broadly divided as biopsies supportive for patient management and biopsies essential for patient management. Biopsies essential for patient management (n=16) comprise vasculitic neuropathy (n=9), lepromatous neuropathy (n=4), hereditary motor sensory neuropathy (n=1) and CIDP (n=2). Biopsies supportive for patient management (n=14) comprise axonal neuropathies (n=6), demyelinating neuropathies (n=5) and mixed neuropathies (predominantly Axonal with secondary demyelinating features, n=3). No diagnostic pathology was identified in 13 cases (24%). Conclusion: With the advent of molecular tests and electrophysiologic examinations, nerve biopsy is losing its charm. However, its contribution still hold grounds in specific etiologies like Vasculitic neuropathy, lepromatous neuropathy and to some extent in management of CIDP. Increase in awareness among the pathologists of the histomorphology is essential to aid the physicians managing these patients. Keywords: Nerve biopsies, Axonal neuropathy, Demyelinating neuropathy, CIDP

Congenital Insensitivity to Pain with Anhidrosis (CIPA): A Comprehensive Review

Abstract: Congenital Insensitivity to Pain with Anhidrosis (CIPA), also known as hereditary sensory and autonomic neuropathy type IV (HSAN IV), is a rare genetic disorder characterized by the inability to perceive pain and a lack of sweat (anhidrosis). This review aims to provide a comprehensive understanding of CIPA, including its clinical features, genetic basis, diagnostic challenges, and management strategies.