Two novel missense mutations causing adrenoleukodystrophy in Italian patients

The authors present two new missense mutations in exon 1 of the adrenoleukodystrophy (ALD) gene. The first, a C813T transition, results in the substitution Pro143 Ser in the third putative transmembrane domain of the adrenoleukodystrophy protein (ALDP) in an adult onset case. The second, a de novo C709T transition, results in a substitution Ser 108 Leu between the second and the third putative transmembrane segments, in a childhood case.

Hepatitis C virus infection of peripheral nerves in type II cryoglobulinaemia

Peripheral neuropathy is a frequent complication in patients suffering from type II mixed cryoglobulinaemia (mCGII), a sort of vasculitis that is strongly associated with hepatitis C virus (HCV) infection and characterised by high concentrations of anti-HCV antibodies and HCV RNA in the cryoprecipitates. We report the finding of HCV RNA in homogenates of nerve biopsies from five such patients, by reverse transcription-polymerase chain reaction (RT-PCR) amplification of different regions of the viral genome. HCV RNA was localized in epineurial cells by in situ RT-PCR. Our data suggest that HCV infection of nerves plays a major role in mCGII-associated neuropathy.

Neuroaxonal dystrophy with dystonia and pallidal involvement

Infantile neuroaxonal dystrophy (INAD) is an autosomal recessive disease of infantile onset, characterised by progressive clinical course, multi-systemic involvement and widespread presence of dystrophic axons in both the central and peripheral nervous system. Clinical, neurophysiological and neuroradiological criteria of the disease are established, but the occurrence of atypical cases is known. Since the availability of molecular markers is still lacking, diagnostic evidence in vivo is provided by the presence of specific axonal lesions distally in the peripheral nerve fibres. In two children who had a protracted course of the disease with dystonic postures of the upper limbs and showed dystrophic axons following sural nerve biopsy, bilateral pallidal hypointensity was observed after T2-weighted MRI scans. These findings are consistent with iron deposition, and are usually observed in Hallervorden-Spatz syndrome (HSS), a condition which is also characterised by dystrophic axons diffusely present in the central nervous system, but without peripheral nervous system involvement. These observations raise the issue of different phenotypes of INAD, and are consistent with the existence of intermediate forms between INAD and HSS. Altered mechanisms of iron storage and transport to and from the cellular compartments may play a role in the pathogenesis of the disease.

Two novel frameshift mutations in the adrenoleukodystrophy gene in Italian patients

Two novel frameshift adrenoleukodystrophy mutations in two families were identified: a complex dinucleotide deletion/tetranucleotide insertion at 1116 TC-->GAGA (codon 244 [serine]) and an AG deletion at nucleotide 1462 (codon 359 [glutamic acid]). Both mutations are predicted to cause premature termination of protein synthesis. The patients were affected by childhood cerebral adrenoleukodystrophy and by adrenomyeloneuropathy with mild Addison disease, respectively.

Nerve conduction changes during lower limb lengthening. Somatosensory evoked potentials (SEPs) and F-wave results

The effect of lower limb lengthening on nerve conduction was investigated in 5 achondroplastic subjects who underwent callotasis on a "cross-over" basis. Somatosensory evoked potentials (SEPs) and F waves from the posterior tibial nerve (PTN) were studied preoperatively and then after removal of the axial fixators. SEPs at the end of lengthening showed that both the latency of the plexus potential (P9) and, albeit to a lesser extent, the interpeak time between the plexus and the spinal cord (N15) potentials were significantly increased. The central conduction time (N15-P33) and the amplitude of the scalp responses were not modified. The latencies of the F waves were much longer at the end of bone distraction than in basal conditions. The increases in both PTN SEPs and F-wave latencies are consistent with a slowing of conduction The extent of these latency shifts correlated closely with the degree of limb lengthening. We calculated that, on average, each cm of lengthening could produce 0.21 msec and 0.22 msec delays respectively, suggesting a similar effect of the stretching on both sensory and motor fibers. Our findings indicated that the damage could be widely distributed along the whole length of the nerve, affecting both the peripheral (trunk) and proximal (plexus and root) segments. The electrophysiological changes were not associated with any persistent clinical complaint.

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.

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.

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.

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.

Neuropsychological and neuroimaging correlates in corticobasal degeneration

The aim of this study was to correlate neuropsychological and neuroimaging findings in corticobasal degeneration (CBD). Three patients with clinical criteria for CBD were examined by means of neuropsychological tests, brain magnetic resonance imaging (MRI), and flow and metabolism neuroimaging techniques. Neuropsychological assessment revealed impairment in executive functions, manual dexterity and motor programming with significant asymmetry between upper limbs. Ideomotor and oral apraxia were also detected, and memory deficits were observed in one patient. MRI revealed cortical dilation of the frontal and peri-rolandic regions, symmetrical in one case and asymmetrical in the other two cases. An increased T2 signal intensity in the posterolateral putamen and substantia nigra ipsilateral to the cortical atrophy was observed in one patient. Asymmetries of both frontal and parietal cortices and basal ganglia were detected in all three patients by 18-fluorodeoxyglucose positron emission tomography; temporal region hypometabolism was associated in one patient. These cortical and subcortical asymmetries were observed in two patients by single photon emission tomography with the tracer technetium Tc 99m hexamethyl propylenamine oxime; cortical asymmetry was observed in only one patient. The results showed that functional neuroimaging findings correlated well with neuropsychological aspects in CBD. Neuroimaging and neuropsychological correlations may contribute toward understanding anatomical and functional abnormalities associated with this neurodegenerative disorder.

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.

Coeliac disease associated with peripheral neuropathy in a child: a case report

Clinical features and pathological findings of sural nerve biopsy are reported of a 3-year-old child affected with coeliac disease who developed a progressive polyneuropathy, unresponsive to a gluten-free diet, nor to vitamin E and folic acid supply. There was no evidence of malabsorption, nor of blood factor deficiency, nor of metabolic abnormalities which might account for the neuropathy. A sural nerve biopsy showed marked loss of myelinated fibres without evidence of regenerative phenomena. Distal involvement and features of nerve pathology are consistent with a "dying-back" mechanism to underlie the nerve damage. The lack of response to a gluten-free diet suggests that direct toxicity of gliadin is not implicated.

Molecular genetic characterization of two metachromatic leukodystrophy patients who carry the T799G mutation and show different phenotypes; description of a novel null-type mutation

Metachromatic leukodystrophy (MLD) is an autosomal recessive storage disease caused by deficiency of the lysosomal enzyme, arylsulfatase A. Two common mutations causing MLD have been characterized and correlations between phenotype and genotype have been established. A third common mutation, T799G, has also been identified in European MLD patients, and is associated with the late-onset forms of the disease. We report the molecular analysis of two Italian MLD patients, with juvenile and adult onset of the disease, respectively, who carried the T799G mutation in compound heterozygosity with different null mutations. A novel rapid mutation detection method is demonstrated for patient screening. One patient has a novel mutation, a T553C [corrected] transition that results in the substitution of Pro for Leu at codon 135, and produces no enzymatic activity in transfection experiments.

A novel mutation which represents the fifth non-pathogenic polymorphism in the coding sequence of the arylsulfatase A gene

A novel mutation, a C-->T transition at nucleotide 455 of the coding sequence of the ARSA gene, was found in a control individual during the search for metachromatic leukodystrophy mutations. Its distribution in three different populations was examined. The frequency of the T allele was 0.058, 0.025 and 0.033, in Italian, German and Greek populations, respectively. The mutation results in no amino acid substitution and can be identified as it creates a a polymorphic site for the restriction endonuclease N/aIII.

LOWER-LIMB LENGTHENING IN SHORT STATURE

We assessed peripheral nerve function during and after lower-limb lengthening by callotasis in 14 patients with short stature, using motor conduction studies.

Four patients with short stature of varying aetiology showed unilateral and one showed bilateral weakness of foot dorsiflexion. Both clinical and electrophysiological abnormalities consistent with involvement of the peroneal nerve were observed early after starting tibial callotasis. There was some progressive electro-physiological improvement despite continued bone distraction, but two patients with Turner’s syndrome had incomplete recovery. A greater percentage increase in tibial length did not correspond to a higher rate of peroneal nerve palsy. The function of the posterior leg muscles and the conduction velocity of the posterior tibial nerve were normal throughout the monitoring period.

The F-wave response showed a longer latency at the end of the bone distraction than in basal conditions; this is probably related to the slowing of conduction throughout the entire length of the nerve.

Ponto-cerebellar hypoplasia with dystonia: clinico-pathological findings in a sporadic case

Microcephaly, absent psychomotor development and dystonic limb movements were the main clinical features of a 3-year-old girl affected by hypoplasia of the pontocerebellar structures. As in the few previously reported cases there are discrepancies between the severity of lesions in the supratentorial and infratentorial compartments. Pathological features such as size reduction of the ventral pons, inferior olive atrophy, dentate nucleus fragmentation, and thinning of the cerebellar cortex suggest an impaired maturation of the involved structures due to a prenatal condition (dated at about 20-28 weeks of gestation). Somatotopic analysis failed to provide conclusive evidence on the primary target of the disease. The affected structures originate from the dorsal rhombencephalic region at about the same gestational age, and their maturation is probably under the control of sets of genes which regulate pattern formation. Early abnormal functioning of such genes might lead to the selected morphogenetical alterations observed in ponto-cerebellar hypoplasia. The normal morphogenetic pattern of the supratentorial structures and the mild lesions observed suggest that their late involvement can be related to a different pathogenetic process.