Frontotemporal dementia and corticobasal degeneration in a family with a P301S mutation in tau

The tau gene has been found to be the locus of dementia with rigidity linked to chromosome 17. Exonic and intronic mutations have been described in a number of families. Here we describe a P301S mutation in exon 10 of the tau gene in a new family. Two members of this family were affected. One individual presented with frontotemporal dementia, whereas his son has corticobasal degeneration, demonstrating that the same primary gene defect in tau can lead to 2 distinct clinical phenotypes. Both individuals developed rapidly progressive disease in the third decade. Neuropathologically, the father presented with an extensive filamentous pathology made of hyperphosphorylated tau protein. Biochemically, recombinant tau protein with the P301S mutation showed a greatly reduced ability to promote microtubule assembly.

Axonal swellings predict the degeneration of epidermal nerve fibers in painful neuropathies

OBJECTIVE

To correlate the density of swellings in intraepidermal nerve fibers (IENF) with the longitudinal measurement of the epidermal innervation density in patients with painful neuropathy and to assess the predictive value of IENF swelling to progression of neuropathy.

METHODS

Fifteen patients with persistent pain in the feet underwent neurologic examination, nerve conduction studies, quantitative sensory examination, and skin biopsies at proximal thigh and distal leg. In all patients and in 15 healthy subjects, IENF density and swelling ratio (no. swellings/no. IENF) were quantified at distal leg. Follow-up study, including IENF density and swelling ratio quantification, was performed a mean of 19.2 months later. Double staining confocal microscope studies using anti-human protein-gene-product 9.5, anti-tubule, anti-neurofilament, and anti-synaptophysin antibodies were performed to assess specific accumulation within swellings. Ultrastructural investigation of IENF was also carried out.

RESULTS

Patients with neuropathy had lower density of IENF and higher swelling ratio than healthy subjects (p < 0.01) at distal leg. At follow-up, patients showed a parallel decrease in both IENF density (p = 0.02) and swelling ratio (p = 0.002). However, swelling ratio remained higher (p = 0.03) than in controls. Progression of neuropathy was confirmed by the decay in sural nerve sensory nerve action potential amplitude. Double immunostaining studies suggest accumulation of tubules and ubiquitin-associated proteins within swellings. Swollen and vacuolated IENF were identified in patients with neuropathy by conventional and immuno-electron microscopy.

CONCLUSIONS

Increased swelling ratio predicted the decrease in IENF density in patients with painful neuropathy. Its quantification could support earlier diagnosis of sensory axonopathy.

Cranial nerve involvement in CMT disease type 1 due to early growth response 2 gene mutation

Mutations in the gene coding for the Schwann cell transcription factor early growth response 2 (EGR2), which seems to regulate myelinogenesis and hindbrain development, have been observed in few cases of inherited neuropathy. The authors describe a unique combination of cranial nerve deficits in one member of a Charcot-Marie-Tooth 1 family carrying an EGR2 mutation (Arg381His). This finding further supports the role of EGR2 in cranial nerve development.

A family with Alzheimer disease and strokes associated with A713T mutation of the APP gene

Three members of an Italian family with autosomal dominant dementia and multiple strokes had the A713T mutation of the APP gene. The neuropathologic examination of the proband disclosed Alzheimer disease (AD) with severe cerebral amyloid angiopathy and multiple infarcts. This indicates that the A713T mutation of the APP gene, lying at the gamma-secretase cleavage site, can be responsible for AD with symptomatic cerebral amyloid angiopathy.

Infantile neuroaxonal dystrophy: neuroradiological studies in 11 patients

We report the imaging findings in 11 patients with infantile neuroaxonal dystrophy. Ten patients underwent 15 MRI examinations; one patient had only CT. Of the ten patients who underwent MRI, eight had cerebellar atrophy and mildly increased signal from the cerebellar cortex on T2-weighted images. With T2 weighting there was slightly increased signal from the dentate nuclei in two patients and from the posterior periventricular white matter in three. We saw four patients with a thin optic chiasm. The only two brothers in the series had markedly low signal from the globus pallidus and substantia nigra on 1.5 T T2-weighted images, as seen in Hallervorden-Spatz disease (HSD). Abnormalities of the globus pallidus may be related to a protracted course of the disease. However, an overlap with HSD should be considered.

Neuropathology of Gerstmann-Sträussler-Scheinker disease

Gerstmann-Sträussler-Scheinker disease is a familial neurodegeneration characterized clinically by adult-onset ataxia, postural abnormalities, and cognitive decline, and pathologically by amyloid deposits mostly localized in the cerebral and cerebellar cortices and the basal ganglia. The disease is due to mutations in the prion protein gene. Processing of the mutant proteins originates the amyloidogenic fragments that accumulate in the tissue. PrP-immunoreactive amyloid deposits are the morphological hallmark of the disease. Hypertrophic astrocytes, activated microglia, and nerve cell loss are consistently associated with PrP-amyloid deposits, while spongiosis, diffuse PrP immunoreactivity, neurofibrillary tangles, Lewy bodies, and long fiber tracts degeneration are occasionally associated. The clinical and pathological variability observed in GSS families is related to both mutations and the M/V polymorphism at codon 129 of the mutated gene.

Role of HIV in the pathogenesis of distal symmetrical peripheral neuropathy

We report the results of a clinical, electrophysiological and pathological study conducted in 18 AIDS patients presenting a distal symmetrical predominantly sensory polyneuropathy (DSPN) characterized by painful dysesthesias as main complaint. Onset of the neuropathy was at CDC (Center for Disease Control) stage II in 2 patients, at CDC stage III in 5 patients and at CDC stage IV in the remainder. Electrophysiological investigation confirmed the presence of an axonal alteration in the sensory nerves, but also revealed motor involvement in all cases. The neuropathological features of sensory nerves were fiber loss and axonal degeneration with macrophagic activation. The expression of monocyte-macrophage markers and of major histocompatibility complex class II antigens appeared up-regulated in endoneurial ramified cells, while expression of CR3, a complement receptor involved in the process of phagocytosis, was down-regulated. In six nerve biopsy samples and in two out of five DSPN dorsal root ganglia we found HIV-related mRNA and protein located in scattered cells of the endoneurium which we presume to be macrophages. These data suggest that: (a) DSPN may occur early in the course of the disease and is not limited to later stages; (b) DSPN is not a ganglionitis but is actually a sensory-motor neuropathy; (c) the virus enters the peripheral nervous system and induces changes in the immunocompetent cell population with activation of macrophages. Storage of the virus inside macrophages may act both as a reservoir for the virus and as a putative cause of nerve damage, probably through release of cytotoxins and/or interaction with trophic factors.

Delayed spongiform leukoencephalopathy after heroin abuse

Here we report the clinical and pathological findings in a 30-year-old drug addict in whom an intravenous injection of heroin led to reversible coma with respiratory depression and heart failure. On regaining consciousness, the patient was found to have rhabdomyolysis with renal failure requiring dialysis and peripheral neuropathy. Three weeks later his neurological condition suddenly deteriorated and delayed encephalopathy developed, leading to death 20 days later. The neuropathological study of the brain disclosed pale, spongy myelin with diffuse reactive astrogliosis and microglial proliferation, without hypoxic necrotic lesions. The cerebral and cerebellar cortices were unchanged. The absence of typical hypoxic lesions and the presence of spongiosis with massive astrocytosis distinguished this case from the previously reported cases of delayed leukoencephalopathy following severe hypoxia. An immunocytochemical study designed to exclude an underlying alteration of the metabolic oxidative pathway detected normal expression of the respiratory chain complexes IV, III and V. Despite the absence of an oxidative chain alteration in our patient, we cannot exclude the possibility that an individual predisposition played a pathogenetic role in this delayed leukoencephalopathy.

Four novel cases of periaxin-related neuropathy and review of the literature

OBJECTIVE

To report 4 cases of autosomal recessive hereditary neuropathy associated with novel mutations in the periaxin gene (PRX) with a review of the literature. Periaxin protein is required for the maintenance of peripheral nerve myelin. Patients with PRX mutations have early-onset autosomal recessive demyelinating Charcot-Marie-Tooth disease (CMT4F) or Déjèrine-Sottas neuropathy (DSN). Only 12 different mutations have been described thus far.

METHODS

Case reports and literature review.

RESULTS

Four patients from 3 unrelated families (2 siblings and 2 unrelated patients) were affected by an early-onset, slowly progressive demyelinating neuropathy with relevant sensory involvement. All carried novel frameshift or nonsense mutations in the PRX gene. The 2 siblings were compound heterozygotes for 2 PRX null mutations (p.Q547X and p.K808SfsX2), the third patient harbored a homozygous nonsense mutation (p.E682X), and the last patient had a homozygous 2-nt insertion predicting a premature protein truncation (p.S259PfsX55). Electrophysiologic analysis showed a severe slowing of motor nerve conduction velocities (MNCVs, between 3 and 15.3 m/s) with undetectable sensory nerve action potentials (SNAPs). Sural nerve biopsy, performed in 2 patients, demonstrated a severe demyelinating neuropathy and onion bulb formations. Interestingly, we observed some variability of disease severity within the same family.

CONCLUSIONS

These cases and review of the literature indicate that PRX-related neuropathies have early onset but overall slow progression. Typical features are prominent sensory involvement, often with sensory ataxia; a moderate-to-dramatic reduction of MNCVs and almost invariable absence of SNAPs; and pathologic demyelination with classic onion bulbs, and less commonly myelin folding and basal lamina onion bulbs.

Congenital hypomyelination neuropathy with Ser72Leu substitution in PMP22

We describe a patient with congenital hypomyelination neuropathy. The pathological and morphometrical findings in the sural nerve biopsy were consistent with a defect of myelin formation and maintenance. Direct sequence analysis of the genomic regions coding the peripheral myelin proteins P0 and PMP22 disclosed a heterozygous missense point mutation that leads to a Ser72Leu substitution in the second transmembrane of PMP22. Codon 72 mutations of PMP22 are associated with different phenotypes encompassing the Dejerine-Sottas syndrome and including congenital hypomyelination neuropathy.

Revelation of a novel CLN5 mutation in early juvenile neuronal ceroid lipofuscinosis

Neuronal ceroid lipofuscinoses (NCLs) are relatively common storage diseases of childhood and early adolescence. Ultrastructural shape of storage cytosomes, type of disease gene, and age of onset serve to classify the different NCLs, some of which appear to cluster in Scandinavian countries. The CLN5 form usually presents as a classical epileptiform encephalopathy of late infancy but a more aggressive cognitive impairment has been described in a single family. We report two sibs harbouring a novel mutation (p.Tyr258Asp) in the CLN5 gene and displaying behaviour disturbances and mental deterioration, rather than epilepsy, as the dominant disease manifestation at onset.

Focal lesions area feature of chronic inflammatory demyelinating polyneuropathy (CIDP)

In a study designed to identify the neuropathological features typical of chronic inflammatory demyelinating polyneuropathy (CIDP), we reviewed the sural nerve biopsy findings in 105 patients with this disorder. The patients' mean age at biopsy was 49 years. In 65% of patients the disease had a progressive and in 35% a relapsing-remitting course. In 47% of cases the disorder was idiopathic; the remainder had various concurrent conditions. All sural nerve biopsy specimens showed varying amounts of active demyelination associated with onion bulbs (48% of cases), endoneurial edema (55%) and inflammatory infiltrates (25%). The immunopathological hallmarks were T cell infiltration with macrophagic activation and up-regulation of major histocompatibility complex (MHC) class II expression, without B cell infiltration or immunoglobulin deposition on myelin sheaths. In 30% of cases some myelin sheaths showed C3d deposition. Analysis of proinflammatory cytokine expression invariably showed interleukin-1 in perivascular and endoneurial ramified cells and tumor necrosis factor-alpha prevalently in epineurial macrophages, whereas it detected interferon-gamma only in samples with perivascular inflammatory cells. This immunological pattern suggests that the cellular components of immunity play the major role in CIDP. In 19% of cases the neuropathological changes had a focal distribution. This distinctive feature corresponded to more active demyelination, more frequent detection of inflammatory infiltrates and more prominent immunological activation, suggesting that focal involvement is a possible step in the course of the disease.

Clinical and pathological correlations in Charcot-Marie-Tooth neuropathy type 1A with the 17p11.2p12 duplication: a cross-sectional morphometric and immunohistochemical study in twenty cases

In a cross-sectional, clinical, and morphometric analysis we assessed the correlation between the clinical and pathological evolution of disease in 20 unrelated patients of various ages affected by Charcot-Marie-Tooth neuropathy type 1A (CMT1A) with the 17p11.2p12 (peripheral myelin protein 22, PMP22) duplication. The severity of neurologic deficits and slowing of motor conduction velocity at the median nerve did not vary significantly with the patients' age. The amount of demyelination was significantly higher below 15 years than in older age groups; in contrast, myelinated fiber and onion bulb densities were similar at all ages. The results indicate that in duplicated CMT1A, the pathological process develops early in life and progresses little during the course of the disease. Younger patients had lower g-ratio values, suggesting that the trigger of demyelination in early years could be a hypermyelination, resulting from PMP22 overexpression. Yet none of the 20 patients examined had immunohistochemical evidence of altered PMP22 expression. The early onset and development of the disorder make it difficult to detect PMP22 overdosage in nerve biopsies.

Antisulfatide polyneuropathy: antibody-mediated complement attack on peripheral myelin

Increased titers of circulating antisulfatide antibodies are consistently associated with a variety of chronic axonal and demyelinating polyneuropathy syndromes. Previous studies have shown that the pattern of antisulfatide binding to neural tissues correlates with the type of neuropathy. This suggests a possible role for antisulfatide antibodies in inducing peripheral nerve dysfunction, although their exact contribution to the pathogenesis of neuropathy is still unknown. We examined sural nerve biopsy specimens from two patients with sensorimotor and small fiber sensory neuropathy associated with high titers of IgM monoclonal antibodies to sulfatide. Electrophysiological and pathological findings were consistent with predominant demyelination in the patient with sensorimotor involvement, whereas evidence of demyelination was obtained only by teased fiber examination in the other patient. The ultrastructural study disclosed in both cases the presence of myelinated fibers with widely spaced myelin, due to a separation of leaflets of the intraperiod lines. Immunocytochemistry, performed on frozen sections, demonstrated the presence of IgM and complement product C3d bound to myelin sheaths of almost all fibers. Few fibers were immunoreactive for complement components C1q and C5. In addition, the terminal complement complex neoantigen C5b-C9, not associated with S protein, was detected on some myelinated fibers. The results suggest that, at the least in some forms of demyelinating neuropathy associated with antisulfatide antibodies, pathological changes are complement mediated. Our data further confirm previous clinical and experimental observations that complement activation initiates separation of myelin intraperiod lines.

Myelin uncompaction in Charcot-Marie-Tooth neuropathy type 1A with a point mutation of peripheral myelin protein-22

BACKGROUND

The peripheral myelin protein-22 (PMP22) gene has four transmembrane domains, two extracellular loops, and a short cytoplasmic tail. Its roles in the peripheral nervous system remain unclear. The most common cause of Charcot-Marie-Tooth neuropathy type 1A (CMT1A) is a PMP22 gene duplication. Missense point mutations in the transmembrane domains are rare alternative causes that have undetermined pathogenetic mechanisms.

OBJECTIVE

To investigate the phenotype-to-genotype correlations in a pedigree with unusual CMT1A.

METHODS

We identified a pedigree with an autosomal dominant motor-sensory neuropathy and severely reduced nerve conduction velocities who did not have the PMP22 duplication. Specimens from sural nerve biopsies from two patients of different ages were evaluated morphometrically. By automated direct nucleotide sequencing we analyzed PMP22 and the gene of the major structural myelin protein zero (P0).

RESULTS

Nucleotide 159 of PMP22 showed an A-to-T heterozygous mutation, predicted to cause an aspartate-to-valine substitution at codon 37 in the first extracellular loop of the protein. The mutation co-segregated with the disease in the pedigree and was absent in 80 healthy controls. The histopathologic phenotype was a de-remyelinating neuropathy with onion bulb formations, characterized by prominent uncompaction of the myelin sheath in the majority of fibers and by frequent tomacula.

CONCLUSION

We have described a novel mutation in the first extracellular loop of PMP22 associated with an atypical CMT1A that overlaps pathologically with CMT1B caused by point mutations in the extracellular domain of P0.

HIV-associated PML presenting as epilepsia partialis continua

Two patients with human immunodeficiency virus (HIV) type 1 infection presented new-onset epilepsia partialis continua (EPC) as an early manifestation of progressive multifocal leukoencephalopathy (PML). EPC occurred with no other seizures and was associated with negative radiographic and electrophysiological findings for several weeks. PML represents an increasingly recognized cause of new-onset seizures in both seropositive and seronegative patients, with no report of EPC as a presenting complaint.

Subunit A of Factor XIII Regulates Subunit B Plasma Concentration

Subunit a of Factor XIII is found absent in homozygotes and reduced in heterozygotes. Since a concomitant reduction of subunit b occurs in these cases, an interaction between the loci controlling the synthesis of the two subunits was suggested. However in the present study we have shown that the administration of subunit a in two totally devoid homozygotes produced an increase of subunit b, reaching the maximum concentration five days after infusion. This strongly suggests that subunit b plasma level is regulated on the subunit a plasma amount.

Novel mutation of the P0 extracellular domain causes a Déjérine-Sottas syndrome

A patient is described with a Déjérine-Sottas syndrome caused by a novel heterozygous Cys(98)Tyr mutation in the extracellular domain of the major peripheral myelin protein zero (P0ex). Homotypical interactions between P0ex tetramers of apposed extracellular faces of the Schwann cell membrane play a crucial part in myelin compaction. The amino acid change disrupts a unique disulphide bond that stabilises the immunoglobulin-like structure of P0ex and it is predicted to cause severe dehypomyelination through dominant negative effects on the wild type protein.

Ictal and nonictal paroxysmal events in infantile neuroaxonal dystrophy: polygraphic study of a case

A 7.5-year-old girl, with infantile neuroaxonal dystrophy (INAD), showed a gradual deterioration from 16 months; at age 5 years she was bedridden, with severe tetraplegia, strabismus, nystagmus and optic atrophy, and dementia. From age 5.5 years, she had paroxysmal tonic events. Videopolygraphic recordings disclosed two different kinds of motor events: (a) epileptic tonic seizures, in wakefulness and sleep, associated with autonomic changes and ictal EEG discharges; and (b) nonepileptic prolonged clusters of brief tonic spasms, without ictal modifications of the EEG. Both motor events were characterized by a minimal and clinically similar tonic contraction of the upper extremities. Video-polygraphic studies are mandatory for a correct paroxysmal event classification and treatment in INAD patients.

A novel mutation af Cln3 associated with delayed-classic juvenile ceroid lipofuscinois and autophagic vacuolar myopathy

Juvenile neuronal-ceroid-lipofuscinosis (JNCL) is a lysosomal storage disease caused by mutations in CLN3. The most frequent mutation is a 1.02-kb deletion that, when homozygous, causes the classical clinical presentation. Patients harboring mutations different than the major deletion show a marked clinical heterogeneity, including protracted disease course with possible involvement of extraneuronal tissues. Cardiac involvement is relatively rare in JNCL and it is usually due to myocardial storage of ceroid-lipofuscinin. Only recently, histopathological findings of autophagic vacuolar myopathy (AVM) were detected in JNCL patients with severe cardiomyopathy. We describe a 35-year-old male showing a delayed-classic JNCL with visual loss in childhood and neurological manifestations only appearing in adult life. He had an unusual CLN3 genotype with an unreported deletion (p.Ala349_Leu350del) and the known p.His315Glnfs*67 mutation. Autophagic vacuolar myopathy was shown by muscle biopsy. At clinical follow-up, moderately increased CPK levels were detected whereas periodic cardiac assessments have been normal to date. Adult neurologists should be aware of protracted JNCL as cause of progressive neurological decline in adults. The occurrence of autophagic vacuolar myopathy necessitates periodic cardiac surveillance, which is not usually an issue in classic JNCL due to early neurological death.

Neuronal ceroid lipofuscinosis: detection of atypical forms

The neuronal ceroid lipofuscinoses (NCL) are progressive neurodegenerative diseases occurring in infancy and adulthood. Atypical forms of these diseases have been described and are particularly represented in the late-infantile and juvenile onset groups. Recent progress in biochemistry and molecular genetics has identified some of these variants as separate disease entities while disclosing the phenotypic variability of some classic forms. We report the results of a retrospective analysis performed on a series of 27 NCL patients, 15 of which were atypical as to clinical and/or pathological findings. Most of such patients, belonging to the late-infantile onset group and displaying homogeneous clinical-pathological features, were suggestive for CLN6. The two atypical juvenile NCL patients had features which resembled the "protracted form" of the disease. Given their relative frequency, strict clinical and pathological criteria are still the most useful tools for identifying and characterizing atypical forms and for defining phenotype-genotype correlations.

IDPN impairs post-traumatic regeneration of rat sciatic nerve

The role played by cytoskeletal proteins in nerve regeneration was investigated in a model in which the axonal transport of neurofilaments (NF) is almost selectively impaired. The administration of beta, beta'-iminodipropionitrile (IDPN), a synthetic lathyrogenic compound, induces an axonopathy characterized by proximal axonal enlargements, due to NF accumulation, and by diffuse atrophic changes associated with spatial segregation of NF from microtubules (MT). We investigated post-axotomy regeneration of rat sciatic nerve following IDPN administration. Changes induced by IDPN, as examined in the proximal and distal nerve stump at 15 and 30 days after lesion, consisted of a statistically significant reduction of the mean axonal diameter (P < 0.0001) as compared to control rats. In addition, the number of regenerating myelinated fibres was smaller in dosed rats (P < 0.001) 15 days after crush, whereas at the later stage the number of axons approached that of control animals. Electrophysiological investigation revealed a delay in target reinnervation in dosed rats. Regenerating IDPN axons, both 15 and 30 days after crush contained fewer NF (P < 0.001), while the number of MT was slightly increased as compared to controls. Taken together, our results suggest that severe alteration of NF transport, coupled with mild alteration of other components of cytoskeletal proteins, impairs the longitudinal and radial growth of regenerating myelinated axons and confirm that the number of NF is the major determinant of the cross-sectional area of each segment of the axon.