Beyond neuropathy in hereditary sensory and autonomic neuropathy type V: cognitive evaluation

Background and purpose:  Hereditary sensory and autonomic neuropathy (HSAN) type V is a very rare disorder. It is characterized by the absence of thermal and mechanical pain perception caused by decreased number of small diameter neurons in peripheral nerves. Recent genetic studies have pointed out the aetiological role of nerve growth factor beta, which is also involved in the development of the autonomic nervous system and cholinergic pathways in the brain. HSAN type V is usually reported not to cause mental retardation or cognitive decline. However, a structured assessment of the cognitive profile of these patients has never been made.
Methods and results:  We performed a throughout evaluation of four HSAN type V patients and compared their performance with 37 normal individuals. Our patients showed no cognitive deficits, not even mild ones.
Discussion and Conclusions:  Although newer mutations on this and related disorders are continuously described, their clinical characterization has been restricted to the peripheral aspects of these conditions. A broader characterization of this rare disorder may contribute to better understand the mechanisms of the nociceptive and cognitive aspects of pain.     

Longitudinal conduction studies in hereditary motor and sensory neuropathy type 1

Motor conduction studies were performed serially in 10 patients, ages 10-62 years, with clinical and electrophysiological criteria of hereditary motor and sensory neuropathy type 1 (HMSN-1) over periods of 11-19 years. Median nerve conduction velocity (MNCV) and distal motor latency showed no significant change on serial studies. Mean median compound muscle action potential (CMAP) amplitude values, however, decreased 66% in 8 patients. Observed clinical progression in HMSN-1, over prolonged periods of time, was not associated with MNCV slowing. However, CMAP amplitude reduction, reflecting progressive axonal loss, correlated with clinical deterioration.     

Late-onset hereditary sensory neuropathy type I due to SPTLC1 mutation: autopsy findings

There is little published information on the autopsy findings in hereditary sensory neuropathy type I (HSN I), and none in genetically confirmed cases. We report the neuropathological findings in a 93-year-old woman with a disease of unusually late onset, who was part of a large HSN I kindred and in whom genetic analysis confirmed an SPTLC1 T399G mutation.     

Calf enlargement in hereditary motor and sensory neuropathy

Six members originating from two families with hereditary motor and sensory neuropathy (hypertrophic and neuronal types) were noted to have enlarged calf muscles. Muscle computed tomography revealed that muscle enlargement in the propositus of the family with the hypertrophic type of HMSN was due to an increase in muscle and/or connective tissue. Computed tomography of the legs of the propositus of the family with the neuronal type of HMSN showed infiltration of the medial head of the gastrocnemius muscle by adipose tissue.     

Novel mutation in the replication focus targeting sequence domain of DNMT1 causes hereditary sensory and autonomic neuropathy IE

DNMT1, encoding DNA methyltransferase 1 (Dnmt1), is a critical enzyme which is mainly responsible for conversion of unmethylated DNA into hemimethylated DNA. To date, two phenotypes produced by DNMT1 mutations have been reported, including hereditary sensory and autonomic neuropathy (HSAN) type IE with mutations in exon 20, and autosomal dominant cerebellar ataxia, deafness, and narcolepsy caused by mutations in exon 21. We report a sporadic case in a Japanese patient with loss of pain and vibration sense, chronic osteomyelitis, autonomic system dysfunctions, hearing loss, and mild dementia, but without definite cerebellar ataxia. Electrophysiological studies revealed absent sensory nerve action potential with nearly normal motor nerve conduction studies. Brain magnetic resonance imaging revealed mild diffuse cerebral and cerebellar atrophy. Using a next‐generation sequencing system, 16 candidate genes were analyzed and a novel missense mutation, c.1706A>G (p.His569Arg), was identified in exon 21 of DNMT1. Our findings suggest that mutation in exon 21 of DNMT1 may also produce a HSAN phenotype. Because all reported mutations of DNMT1 are concentrated in exons 20 and 21, which encode the replication focus targeting sequence (RFTS) domain of Dnmt1, the RFTS domain could be a mutation hot spot.     

Prevalence of hereditary motor and sensory neuropathy in Cantabria

One hundred and forty-four patients with hereditary motor and sensory neuropathy (HMSN) were selected from within a defined area (Cantabria) in Northern Spain, from 1974 to 1984. The series comprises 49 index cases and 95 affected relatives. The prevalence ratio was 28.2 cases per 100,000. The results of the study indicate that the majority of the cases were hereditary as a dominant trait. The prevalence for the Type I HMSN cases did not differ from that of Type II cases. Previous population-surveys of these disorders are compared.     

Hereditary motor and sensory neuropathy type 1 (HMSN1) associated with cranial neuropathy: an autopsy case report

A family with hereditary motor and sensory neuropathy type 1 (HMSN1) is reported. Three patients suffered only pupillary abnormality, two patients showed Adie's syndrome and peripheral neuropathy, and one had cranial neuropathy. Adie's syndrome and severe peripheral neuropathy. Autopsy of the latter revealed reduction of myelinated nerve fibers in the trigeminal, facial and hypoglossal nerves. There was extensive degeneration of the posterior column of the spinal cord. At the anterior horns, loss of motor neurons was observed, particularly at the lumbar level. The anterior and posterior roots showed loss of myelinated fibers. HMSN1 is only rarely associated with cranial neuropathy, and this is probably the first autopsy-proved case.     

Pudendal nerve involvement in patients with hereditary motor and sensory neuropathy

Pudendal nerve involvement was demonstrated by electromyography of perineal muscles and by recordings of their direct and reflex responses on perineal electrical stimulation in 10 patients with hereditary motor and sensory neuropathy. Patients reported no defecation disturbances and the 6 men had good erections. Urinary stress incontinence was seen in those 2 (of 4) female patients who had delivered.     

Hypertrophic neuropathy: atypical appearances resulting from the combination of type I hereditary motor and sensory neuropathy and diabetes mellitus

A nerve biopsy from a patient with type Ia hereditary motor and sensory neuropathy and diabetes mellitus showed hypertrophic changes of atypical appearance. The onion bulbs were composed of a central core of Schwann cells, with or without associated axons, embedded in concentrically arrayed layers of collagen fibrils. These were surrounded either by highly attenuated Schwann cell processes or by fibroblasts. The biopsy showed a severe loss of myelinated axons. It is suggested that it is necessary for the supernumerary Schwann cells of the onion bulbs to be stabilized by associated unmyelinated axons. If these are lost, the Schwann cells atrophy and disappear.     

Late‐onset hereditary sensory and autonomic neuropathy expands the phenotypic spectrum of MFN2‐related diseases

Mutations in the Mitofusin 2 (MFN2) gene have been identified in patients with autosomal dominant axonal motor and sensory neuropathy or Charcot–Marie‐Tooth 2A (CMT2A). Here we describe clinical and pathological changes in an adult patient with sporadic hereditary sensory and autonomic neuropathy (HSAN) due to an MFN2 mutation. The patient was a 53‐year‐old man who had sensory involvement and anhidrosis in all limbs without motor features. The electrophysiological assessment documented severe axonal sensory neuropathy. The sural nerve biopsy confirmed the electrophysiological findings, revealing severe loss of myelinated and unmyelinated fibers with regeneration clusters. Genetic analysis revealed the previously identified mutation c.776 G > A in MFN2. Our report expands the phenotypic spectrum of MFN2‐related diseases. Sequencing of MFN2 should be considered in all patients presenting with late‐onset HSAN.     

Neurofilament light mutation causes hereditary motor and sensory neuropathy with pyramidal signs

To identify novel mutations causing hereditary motor and sensory neuropathy (HMSN) with pyramidal signs, a variant of Charcot‐Marie‐Tooth disease (CMT), we screened 28 CMT and related genes in four members of an affected Japanese family. Clinical features included weakness of distal lower limb muscles, foot deformity, and mild sensory loss, then late onset of progressive spasticity. Electrophysiological studies revealed widespread neuropathy. Electron microscopic analysis showed abnormal mitochondria and mitochondrial accumulation in the neurons and Schwann cells. Brain magnetic resonance imaging (MRI) revealed an abnormally thin corpus callosum. In all four, microarrays detected a novel heterozygous missense mutation c.1166A>G (p.Y389C) in the gene encoding the light‐chain neurofilament protein (NEFL), indicating that NEFL mutations can result in a HMSN with pyramidal signs phenotype.     

线粒体融合蛋白2基因新突变导致的遗传性运动感觉性神经病6型一家系

目的 报道1个遗传性运动感觉性神经病6型家系的临床表现、病理改变以及基因突变特点。方法 先证者男性,15岁。患者5岁出现双下肢无力,症状进行性加重,伴随出现双足跟腱挛缩;11岁开始出现慢性进行性视力下降;12岁出现双手肌肉萎缩,无肢体麻木。周围神经传导速度检查显示诱发电位未能引出或波幅显著下降,感觉神经较运动神经改变更明显。视诱发电位提示双眼P100潜伏期均延长,波幅正常。眼底照相提示视神经萎缩,视网膜电图正常。患者母亲7岁时开始出现走路费力,10岁出现视力下降。对先证者进行腓肠神经活体组织检查。对先证者及其母亲进行线粒体融合蛋白2( MFN2)基因测序,100名健康人作为正常对照。结果 腓肠神经病理改变主要为有髓神经纤维显著减少,电镜检查发现个别有髓神经纤维出现洋葱球样结构和再生簇结构,个别神经纤维的轴索内可见线粒体聚集和空泡化。先证者和母亲的MFN2基因第19号外显子存在c.2218T＞C杂合突变,导致MFN2第740位的色氨酸由精氨酸替代(W740R)。100名健康对照没有发现该突变。结论 MFN2基因c.2218T＞C突变导致了遗传性运动感觉性神经病6型,其视力下降多出现在脊神经损害之后,周围神经可以存在髓鞘损害。     

Autosomal recessive type II hereditary motor and sensory neuropathy with acrodystrophy

A family is described with presumed autosomal recessive inheritance in which three siblings developed a progressive neuropathy that combined limb weakness and severe distal sensory loss leading to prominent mutilating changes. Electrophysiological and nerve biopsy findings indicated an axonopathy. The disorder is therefore classifiable as type II hereditary motor and sensory neuropathy (HMSN II). The clinical features differ from those reported in previously described cases of autosomal recessive HMSN II. This disorder may therefore represent a new variant. Received: 16 April 1998 Received in revised form: 26 June 1998 Accepted: 7 July 1998     

Clinical features of a family with late-onset distal hereditary motor neuropathy harboring p.Pro39Leu variant of HSPB1

Background and Aims

Pathogenic variants of HSPB1, the gene encoding the small heat shock protein 27, have been reported to cause autosomal dominant distal hereditary motor neuropathy (dHMN) type II and autosomal dominant Charcot–Marie-Tooth (CMT) disease with minimal sensory involvement (CMT2F). This study aimed to describe the clinical features of patients in a family with late-onset dHMN carrying the Pro39Leu variant of HSPB1.

Methods

Whole-exome sequence analysis identified a heterozygous pathogenic variant (Pro39Leu) of HSPB1 in the proband. The presence of the HSPB1 Pro39Leu variant in two affected individuals was confirmed using direct nucleotide sequence analysis.

Results

Both patients exhibited distal muscle weakness with lower extremity predominance and no obvious sensory deficits, leading to a clinical diagnosis of late-onset dHMN. Nerve conduction studies (NCSs) revealed a subclinical complication of sensory disturbance in one of the patients. The clinical and electrophysiological findings of patients with the HSPB1 Pro39Leu variant in this study and previous reports are summarized.

Interpretation

This study suggests that the clinical spectrum of patients carrying HSPB1 Pro39Leu variants, especially the disease onset, might be broader than expected, and HSPB1 variants should be considered in patients diagnosed with late-onset dHMN. Furthermore, patients with dHMN may have concomitant sensory deficits that should be evaluated using NCSs.     

Leber's hereditary optic neuropathy associated with a disorder indistinguishable from multiple sclerosis in a male harbouring the mitochondrial DNA 11778 mutation

This report describes a multiple sclerosis (MS)-like disorder in a male patient with Leber's hereditary optic neuropathy (LHON) harbouring the mitochondrial DNA 11778 base pair mutation. Given the population frequencies of MS and LHON, coincidental occurrence is unlikely. Hypothetically the mitochondrial mutation underlying LHON may contribute to presumably immunologically mediated involvement of other myelinated axons in the central nervous system in susceptible individuals, producing a disorder indistinguishable from MS. We recommend that investigation for oligoclonal bands in CSF, evoked potentials and MR brain scan in these patients be supplemented with mitochondrial DNA analysis.     

Hereditary sensory neuropathy with deafness and dementia: a clinical and neuroimaging study

We describe three sibling patients with autosomal dominantly inherited sensory neuropathy, sensorineural hearing loss and dementia. The features of cognitive-behavioral deficits in the patients, including executive dysfunction, apathy, indifference and inattention, were consistent with a frontal lobe dysfunction. Magnetic resonance imaging showed a diffuse brain atrophy. A fluorodeoxyglucose positron emission tomography in one patient and a single photon emission computed tomography in another demonstrated a glucose hypometabolism or a hypoperfusion in the medial frontal and thalamic regions. Primary frontal involvement or frontal dysfunction secondary to thalamic lesions may contribute to the nature of dementia in these patients.     

Eccrine sweat glands are not innervated in hereditary sensory neuropathy type IV

Summary The ultrastructural study of a skin biopsy in a patient afflicted with hereditary sensory neuropathy type IV (congenital insensitivity to pain with anhidrosis) did not reveal any unmyelinated axons or axonal terminals around eccrine sweat glands but only proccsses, partially covered by a basement membrane and therefore resembling Schwann cell processes. The absence of such unmyelinated axons in close proximity to eccrine sweat glands where they normally occur appears to be the morphological equivalent to the anhidrosis and also corresponds to the deficiency of unmyelinated axons in the sural nerve of the same patient, as previously reported.Supported by the Deutsche Forschungsgemeinschaft, grant no. Go 185/3