Gene mapping in Gypsies identifies a novel demyelinating neuropathy on chromosome 8q24.

Founder effect and linkage disequilibrium have been successfully exploited to map single gene disorders, and the study of isolated populations is emerging as a major approach to the investigation of genetically complex diseases. In the search for genetic isolates ranging from Pacific islands to Middle East deserts, the 10 million Gypsies resident in Europe have largely escaped the attention of geneticists. Because of their geographical ubiquity, lack of written history and the presumed social and cultural nature of their isolation, Gypsies are construed as not meeting the criteria for a well defined founder population. Gypsy society has a complex structure with subdivisions and stratifications that are incomprehensible to the surrounding populations. Marginalization by the health care systems in most countries results in a lack of information on causes of morbidity and mortality and little is known about hereditary disorders or the population genetic characteristics of Gypsies. This study is the first example of mapping a disease gene in endogamous Gypsy groups. Using lod score analysis and linkage disequilibrium, we have located a novel demyelinating neuropathy to a narrow interval on chromosome 8q24. We show that the disease, occurring in Gypsy groups of different identity and history of migrations, is caused by a single mutation whose origin predates the divergence of these groups.

The use of nerve and muscle biopsy in the diagnosis of vasculitis: a 5 year retrospective study.

INTRODUCTION: Peripheral nerve vasculitis is an important condition which can be diagnostically challenging and is one of the principal current indications for nerve and muscle biopsy. Previous studies have suggested that combined nerve and muscle biopsy (usually of the superficial peroneal nerve and peroneus brevis muscle) produces a higher diagnostic yield than nerve biopsy alone in the investigation of vasculitis. OBJECTIVE: To determine whether in our two centres combined nerve (usually the sural) and muscle (usually the vastus lateralis) biopsy improved diagnostic yield compared with nerve biopsy alone. METHODS: We interrogated our database of all nerve biopsies (usually of the sural nerve) performed at our institutions over 5 years and identified 53 cases of biopsy proven peripheral nerve vasculitis. Clinicopathological and neurophysiological data in these patients were reviewed. RESULTS: The most common clinical presentation was with a painful asymmetric axonal polyneuropathy or mononeuritis multiplex (66% of cases). Nerve biopsy demonstrated definite vasculitis in 36%, probable vasculitis in 62% and no vasculitis in 2% of cases. In 24 patients a muscle biopsy (usually the vastus lateralis) was also performed and vasculitis was demonstrated in 46% of these (in 13% showing definite and 33% probable vasculitis). There was only one patient in whom vasculitis was demonstrated in muscle but not in peripheral nerve. CONCLUSION: Combined nerve (usually sural) and vastus lateralis muscle biopsy did not significantly increase the diagnostic yield compared with nerve biopsy alone. A sensible approach to the diagnosis of peripheral nerve vasculitis is to choose a nerve to biopsy which is clinically affected and amenable to biopsy. If the sural nerve is chosen, the data suggest that it is not routinely worth doing a vastus lateralis biopsy at the same time, whereas if the superficial peroneal nerve is chosen, it seems appropriate to do a combined superficial peroneal nerve and peroneus brevis biopsy. It is still not known if both the sural and superficial peroneal nerves are involved clinically which one gives the higher yield if biopsied.

Familial amyloid polyneuropathy.

Familial amyloid polyneuropathy (FAP) is most commonly associated with variant plasma transthyretin, although it has also been described in association with mutant apolipoprotein A-1 and gelsolin. There are now approximately 26 point mutations in the transthyretin gene associated with FAP. Because of the overlapping clinical phenotypes described with these mutations, it is now more appropriate to classify the various forms of FAP according to the underlying genetic defect rather than on clinical grounds. Many questions concerning the amyloidogenic nature of transthyretin and the variability of organ involvement depending on the underlying mutation remain unanswered. The recent use of liver transplantation for treatment appears to be promising.

Morphometric and freeze-fracture studies on peripheral nerve in shiverer mice.

Observations have been made on the peripheral nerves of shiverer (shi/shi) mice in comparison with control animals. Although this mutant lacks P1 myelin basic protein in peripheral and central myelin, myelin is defective only in the central nervous system. No ultrastructural abnormalities were observed in the shiverer nerves. Myelin spacing was normal. The density and distribution of intramembranous particles on the E and P faces of myelin and in the axolemma of myelinated and unmyelinated axons did not differ between the shiverer and control mice. Morphometric studies showed that external myelinated fiber diameter was significantly less and that myelin thickness was slightly but significantly greater in relation to axon diameter in the shiverer mice, suggesting a minor degree of axonal atrophy. It is concluded that P1 protein is not necessary for the formation and maintenance of the normal structure of peripheral myelin. The failure to detect differences in intramembranous particle density in myelin between shiverer and control mice indicates that P1 protein is not detected in freeze-fracture preparations.

A case of severe congenital chronic inflammatory demyelinating polyneuropathy with complete spontaneous remission.

Chronic inflammatory demyelinating polyneuropathy (CIPD) is characterised by progressive weakness, hyporeflexia and electrophysiological evidence of demyelination with maximal neurological deficit reached after at least 8 weeks progression. CIPD rarely affects children. We present a neonate with clinical features compatible with congenital CIPD. A term male infant of non-consanguineous parents was referred to us at birth with weakness and contractures affecting his legs, suggesting a prenatal onset of immobility. He also had evidence of bulbar dysfunction with poor suck, recurrent aspiration and requiring nasogastric feeding. He had no antigravity movements in the legs, bilateral wrist drop, distal joint contractures and absent deep tendon reflexes. Electromyography showed neurogenic changes, with nerve conduction velocities markedly reduced, increased distal motor latency and dispersed compound muscle action potentials. Cerebrospinal fluid protein was raised. Sural nerve biopsy demonstrated decreased numbers of myelinated fibres and inflammatory cell infiltrates. Muscle biopsy showed denervation. He only received supportive treatment and by 6 months he had fully recovered, and all electrophysiological parameters had normalised.

Hereditary motor and sensory neuropathy-Lom (HMSNL) in a Spanish family: clinical, electrophysiological, pathological and genetic studies.

The clinical, electrophysiological, pathological and genetic findings are described in the first Spanish family diagnosed with hereditary motor and sensory neuropathy type Lom (HMSNL) initially identified by Kalaydjeva et al. in 1996. The three affected patients belong to a non-consanguineous family with Gypsy background that were followed up over 10 years. Serial clinical and neurophysiological examinations and genetic analysis were undertaken in every patient. Sural nerve biopsy was performed in the oldest patient. The clinical features are similar to those previously described in HMSNL and all of them showed abnormal brain auditory evoked potentials. The oldest brother developed sensorineural deafness at the age of 20. Conduction velocities were unobtainable in all patients and nerves tested except for the median nerve in the youngest child in whom conduction was severely slowed. Neuropathological examination revealed a severely depleted nerve with very few surviving myelinated fibers which possessed thin myelin sheaths. Schwann cell processes were arranged in circular configurations without typical onion bulb configuration. Genetic analysis showed that the maternal chromosome inherited by all three affected siblings displayed a very unusual haplotype. Our patients show the characteristic clinical, electrophysiological and pathological findings described in HMSNL and represent the first reported Spanish family affected from the disease. The genetic findings in this family have contributed to refine the HMSNL critical linkage region.

Inherited early onset severe axonal polyneuropathy with respiratory failure and autonomic involvement.

We report dizygotic twins who first presented at the age of 6 months with severe diaphragmatic weakness and marked abnormalities of autonomic function. A female sibling had earlier died from a disorder with similar clinical features. Both twins had a severe axonal polyneuropathy with generalized hypotonic limb weakness together with diaphragmatic paralysis resulting in respiratory failure. Associated features were tachycardia, increased sweating, elevated body temperature, and hypertension, suggesting autonomic dysfunction. Nerve conduction studies indicated an axonopathy affecting both motor and sensory nerve fibres. Sural nerve biopsy in one twin performed at the age of 7 months showed a reduced population of myelinated nerve fibres, particularly those of larger diameter, with no indication of hypomyelination, demyelination or axonal atrophy. Examples of axonal forms of hereditary motor and sensory neuropathy (HMSN) with onset in infancy are very rare and autonomic involvement associated with this condition has not so far been described.

Hereditary motor and sensory neuropathy--Lom (HMSNL): refined genetic mapping in Romani (Gypsy) families from several European countries.

Hereditary motor and sensory neuropathy type Lom, initially identified in Roma (Gypsy) families from Bulgaria, has been mapped to 8q24. Further refined mapping of the region has been undertaken on DNA from patients diagnosed across Europe. The refined map consists of 25 microsatellite markers over approximately 3 cM. In this collaborative study we have identified a number of historical recombinations resulting from the spread of the hereditary motor and sensory neuropathy type Lom gene through Europe with the migration and isolation of Gypsy groups. Recombination mapping and the minimal region of homozygosity reduced the original 3 cM hereditary motor and sensory neuropathy type Lom region to a critical interval of about 200 kb.

Reduced susceptibility of T cell-deficient rats to induction of experimental allergic neuritis.

Lewis rats were made deficient in T cells by adult thymectomy and lethal irradiation, and then reconstituted with T cell-free bone marrow. Their ability to develop experimental allergic neuritis (EAN) was compared with normal rats. The majority of T cell-deficient rats remained clinically and histologically unaffected, whereas all but one of the normal rats developed severe EAN. Those T cell-deficient animals which succumbed to EAN were found to have a significantly higher percentage of residual blood T lymphocytes than those which did not. Full susceptibility to EAN was restored by an inoculum of whole thoracic duct lymphocytes (TDL) from normal animals but not by TDL depleted of T cells. The results therefore provide direct confirmation that T cells are a requirement for the development of EAN.

Attempts to transfer experimental allergic neuritis with lymphocytes.

Attempts have been made to transfer experimental allergic neuritis (EAN) both by the intraneural and the intravenous injection of cells derived from Lewis rats with the disease into naive recipients of the same strain. Lymph node cells obtained 12 and 15 days after inoculation with bovine dorsal root in Freund's complete adjuvant were injected intraneurally. A small number of demyelinated axons were observed, but clinical weakness was not evident. Lymph node cells, lymph node cells cultured with concanavalin A, or cultured spleen cells from animals with EAN were transferred intravenously to normal rats. Uncultured lymph node cells were transferred to X-irradiated animals. There were no clinical or histological differences between these recipients and controls receiving cells from rats inoculated with Freund's adjuvant alone. The findings are discussed in relation to previous reports of attempts to transmit EAN by cell transfer.

A freeze-fracture study of the perineurium in normal and protein-deprived rats.

Observations have been made using the freeze-fracture replication technique on the perineurium of normal and protein-deprived rats in which its permeability barrier function is known to be deficient. The perineurial cells of young normal rats possessed belt-like tight junctions (zonulae occludentes) at the borders and maculae occludentes at sites remote from their borders. In older rats, the zonulae occludentes were more prominent and the maculae occludentes relatively less frequent. No abnormalities were detected in the tight junctions of young rats with early induction of protein deficiency but this may have been related to sampling problems. In older severely protein-deficient animals, although many of the tight junctions were normal, some were abnormal and contained focal regions of dispersed strands. The density of caveolae in the surface membrane of the perineurial cells of older rats with severe protein deficiency was significantly greater than in the control animals. This provides support for the view that the pinocytotic-like vesicles of perineurial cells are involved in transport of substances across the cells. The increased numbers of caveolae in the protein deficient rats may reflect increased transcellular traffic. There were considerable differences in the density of P-face IMPs between the different perineurial lamellae, but the results did not allow a decision to be made as to whether there was a polarization of the cells between their endoneurial and epineurial aspects. No differences were detected in the density of P-face IMPs between the young control and protein-deprived rats. In the perineurium of the older rats with protein deficiency, IMP density was significantly greater in the E face than in the controls but not different in the P face. The delay in the development of enzymatic activity in the perineurium of protein-deficient rats that has been demonstrated histochemically is therefore not paralleled by a reduction in IMPs.

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.

Epineurial microvasculitis in proximal diabetic neuropathy.

Amongst the focal and multifocal neuropathies that are associated with diabetes mellitus one of the most common is a proximal predominantly motor lower limb neuropathy. Recent evidence has indicated that, at least in a proportion of cases, this may have an inflammatory basis. We have examined a consecutive series of 15 cases of proximal diabetic neuropathy (diabetic amyotrophy). These were characterized by proximal pain and asymmetric proximal or generalized lower limb muscle weakness, associated in some cases with radicular sensory involvement. Two-thirds of the patients had an accompanying distal symmetric sensory polyneuropathy. Biopsy of the intermediate cutaneous nerve of the thigh, a sensory branch of the femoral nerve, showed epineurial microvasculitis in 3 patients and nonvasculitic epineurial inflammatory infiltrates in another case. In a further case, microvasculitis was found in both in the sural nerve and a quadriceps muscle biopsy specimen. The detection of inflammatory changes appeared to be correlated with the occurrence of sensory radicular involvement. Whether similar changes are present in muscle nerves in this predominantly motor syndrome requires further study. Nevertheless, the present observations confirm the view that secondary vasculitic or other inflammatory reactions may contribute to some forms of diabetic neuropathy.

Effects of nonenzymatic glycosylation of extracellular matrix components on cell survival and sensory neurite extension in cell culture.

Diabetic sensory polyneuropathy is characterized by a distal axonopathy of dying-back type. It is accompanied by a failure of axonal regeneration, in which nonenzymatic glycosylation (glycation) of the extracellular matrix may be involved. In the present study, the effects of glycation of collagen IV and laminin, major components of basal lamina, on neuron survival and neurite extension were investigated in tissue culture. Fast glycation of laminin was achieved by incubation with glycolaldehyde and glycation of collagen IV by incubation with glucose. The degree of glycation was estimated by fluorescence analysis. Glycated or nonglycated laminin or collagen IV were used as substrates for culture of dorsal root ganglion (DRG) neurons from neonatal rats. Cultures were assessed for the proportion of cells attaching to the substrate, surviving and bearing neurites. Cell attachment and the proportion bearing neurites were significantly reduced on collagen IV glycated for 2 weeks, but survival was only affected by glycation for 4 or 5 weeks. All 3 parameters were significantly reduced on glycated compared with unglycated laminin. Glycation of both laminin and collagen IV produced considerable morphological differences in the cultured neurons on scanning electron microscopy. Dissociated DRG neurons from adult animals with streptozotocin-induced diabetes cultured on nonglycated substrates survived less well and produced fewer neurites. Glycation of collagen IV and laminin thus affects neuronal survival, neurite production and cell morphology, and diabetes affects both the survival of sensory neurons in culture and their ability to extend neurites.

Cerebrotendinous xanthomatosis: clinical, electrophysiological and nerve biopsy findings, and response to treatment with chenodeoxycholic acid.

A 30-year-old patient with cerebrotendinous xanthomatosis was studied over a 6-year period. The clinical manifestations were cataracts, intellectual deterioration, ataxia, palatal and pharyngeal myoclonus, corticospinal tract damage and an electrophysiologically demonstrated sensorimotor peripheral neuropathy. Peripheral motor and sensory nerve conduction velocity was slowed. Sural nerve biopsy revealed reduced densities of both myelinated and unmyelinated axons and teased fibres showed evidence of axonal regeneration and some remyelination. The loss of myelinated nerve fibres particularly affected those of larger diameter, thus contributing to the slowing of nerve conduction. Chenodeoxycholic acid treatment for two separate periods of 10 and 6 months each increased nerve conduction velocity. This electrophysiological improvement was not matched by detectable clinical neurological improvement.

The clinical spectrum of peripheral neuropathies associated with benign monoclonal IgM, IgG and IgA paraproteinaemia. Comparative clinical, immunological and nerve biopsy findings.

Observations have been made on a consecutive series of 62 patients with peripheral neuropathy associated with benign monoclonal paraproteinaemia. The paraprotein class was IgM in 46 cases, IgG in 11 and IgA in 5. Although showing variations between patients, the clinical picture was similar for those with either IgM or IgG paraproteins, usually consisting of a late-onset, slowly progressive, distal sensorimotor demyelinating polyneuropathy, often with tremor and ataxia as prominent features. Tremor was slightly more common in patients with IgM paraproteins, in whom there was a male preponderance. The patients with both paraprotein classes were indistinguishable clinically and electrophysiologically from chronic idiopathic demyelinating polyneuropathy. In the 5 patients with an IgA paraprotein, there was a distal sensorimotor neuropathy in 4 which was demyelinating in 1. In 1 there was proximal demyelinating motor neuropathy. Immunoglobulin deposition on myelin was observed only in the patients with IgM paraproteinaemia, more commonly with a kappa light chain. No deposition of immunoglobulin in the endoneurium was seen. IgM deposits on the perineurium are a feature of normal nerve and were present in all cases. Widely spaced myelin was confined to cases with IgM paraproteins in which immunoglobulin deposition was detected on myelin. The response to treatment could not be assessed systematically but, in general, the patients with IgG and IgA paraproteins responded more satisfactorily (to corticosteroids, cytotoxic drugs, or plasma exchange) than did those with an IgM paraprotein.

Focal cranial nerve involvement in chronic inflammatory demyelinating polyneuropathy: clinical and MRI evidence of peripheral and central lesions.

Five cases of chronic inflammatory demyelinating polyneuropathy are described in which cranial nerve involvement accompanied a more generalized neuropathy. Clinical, electrophysiological, radiological and nerve biopsy findings are presented. Cranial nerve lesions in this form of polyneuropathy may be related to lesions of the peripheral nerves or of the central nervous system, when they may be accompanied by MRI evidence of more widespread CNS demyelinating lesions. In cases of early onset, the occurrence of focal cranial nerve lesions may serve to distinguish chronic inflammatory from inherited demyelinating polyneuropathies.

Recurrent experimental allergic neuritis. An electron microscope study.

Experimental allergic neuritis has been induced in 52 guinea pigs by the inoculation of rabbit peripheral nerve in Freund's adjuvant. The majority of the animals developed an acute monophasic illness after a mean interval of 16 days and, if they survived, recovered fully after an average period of 52 days. Two animals displayed a more chronic course and 1 animal relapsed spontaneously after clinical recovery had occurred. Twenty-three animals that recovered were re-inoculated when recovery was complete and in 4 a relapse was induced. In the remainder, no clinical response was observed, even after repeated reinoculations. The ultrastructural appearances in the animals with a monophasic illness were similar to those previously reported. The appearances differed markedly in those animals that were induced to relapse and were similar to those in the animal that relapsed spontaneously. The findings indicated persistent demyelination and remyelination with striking hypertrophic changes (onion bulb neuropathy). The possible reasons for the differences between the two groups are discussed.

Disease patterns in experimental allergic neuritis (EAN) in the Lewis rat. Is EAN a good model for the Guillain-Barré syndrome?

Lewis rats develop experimental allergic neuritis (EAN) when injected with bovine dorsal root (BDR) emulsified in complete Freund's adjuvant (CFA). In this study the susceptibility to EAN and subsequent relapse was studied in animals ranging from 4 to 25 weeks of age. Older animals exhibited a severe acute illness which was monophasic over the period of observation, whereas younger animals developed a less severe and frequently relapsing illness. Very young animals often relapsed more than once and sometimes to a more severe degree than shown in their first attack. Older animals which were in the late recovery stage of EAN (44 days after injection with BDR/CFA) were completely resistant to a second challenge with antigen. Young adult animals also developed resistance but not as strongly as the older animals. Animals first injected at weaning developed resistance as in the adults, but the analysis is complicated by the occurrence of spontaneous relapses. Because of differences in disease pattern between EAN and acute inflammatory polyneuropathy (Guillain-Barré syndrome) in man, caution should be exercised in drawing too close a parallel between the animal model and the human disease. The affinities may be closer to chronic relapsing inflammatory polyradiculopathy in man.