Phenotypic spectrum of MFN2 mutations in the Spanish population.

INTRODUCTION: The most common form of axonal Charcot-Marie-Tooth (CMT) disease is type 2A, caused by mutations in the mitochondrial GTPase mitofusin 2 (MFN2). OBJECTIVE: The objective of our study is to establish the incidence of MFN2 mutations in a cohort of Spanish patients with axonal CMT neuropathy. MATERIAL AND METHODS: Eighty-five families with suspected axonal CMT were studied. All MFN2 exons were studied through direct sequencing. A bioenergetics study in fibroblasts was conducted using a skin biopsy taken from a patient with an Arg468His mutation. RESULTS: Twenty-four patients from 14 different families were identified with nine different MFN2 mutations (Arg94Trp, Arg94Gln, Ile203Met, Asn252Lys, Gln276His, Gly296Arg, Met376Val, Arg364Gln and Arg468His). All mutations were found in the heterozygous state and four of these mutations had not been described previously. MFN2 mutations were responsible for CMT2 in 16% +/- 7% of the families studied and in 30.8 +/- 14.2% (12/39) of families with known dominant inheritance. The bioenergetic studies in fibroblasts show typical results of MFN2 patients with a mitochondrial coupling defect (ATP/O) and an increase of the respiration rate linked to complex II. CONCLUSION: It is concluded that mutations in MFN2 are the most frequent cause of CMT2 in this region. The Arg468His mutation was the most prevalent (6/14 families), and our study confirms that it is pathological, presenting as a neuropathy in a mild to moderate degree. This study also demonstrates the value of MFN2 studies in cases of congenital axonal neuropathy, especially in cases of dominant inheritance, severe clinical symptoms or additional symptoms such as optic atrophy.

Two Spanish families with Charcot-Marie-Tooth type 2A: clinical, electrophysiological and molecular findings.

Mutations in the Mitofusin 2 (MFN2) gene have been related to the axonal type of Charcot-Marie-Tooth type 2 (CMT 2A). We report the first two Spanish families with CMT 2 and mutations in MFN2 gene. Molecular studies of one family with late onset revealed the novel mutation Arg364Gln. The affected family members presented mild clinical and electrophysiological worsening after 14 years of follow-up. The other family presented an early onset and optic atrophy. Molecular studies revealed the Arg94Gln mutation. This is the first report of a family in which this mutation is related to optic atrophy. Molecular analysis aimed at detecting mutations of MFN2 could be extremely useful in mild axonal neuropathies with slow evolution and indispensable in cases of dominant inheritance or optic atrophy. Population studies of mutations in MFN2 should be undertaken to discover the real frequencies in the Mediterranean area.

Transcription-terminating mutation in telethonin causing autosomal recessive muscular dystrophy type 2G in a European patient.

A 27-year-old woman of Moldavian origin presented at the age of 15 with progressive proximal limb weakness and painful cramps in her calf muscles. Clinical examination revealed prominent muscle weakness in proximal muscles of the lower extremities and distal anterior compartment of legs, and mild weakness in shoulder girdle muscles. In addition, she had marked calf hypertrophy, muscle atrophy involving the anterior and posterior compartments of the thighs, and the distal anterior compartment of legs, as well as mild scapular winging and hyperlordosis. A muscle biopsy taken from the biceps brachii showed mild dystrophic changes, absent vacuoles, and abundant lobulated fibers. Immunofluorescence and Western blot assays demonstrated complete telethonin deficiency. Molecular analysis revealed a homozygous Trp25X mutation in the telethonin (TCAP) gene resulting in termination of transcription at an early point. Four families from Brazil with telethonin deficiency have previously been reported and classified as LGMD2G, but the actual frequency of this disease is unknown. With this current identification of a case outside the Brazilian population, telethonin mutation-associated LGMD should be considered worldwide.

Musk-antibody positive myasthenia gravis presenting with isolated neck extensor weakness.

Dropped head sign is characterized by the gradual forward sagging of the head due to weakness of neck extensor muscles. This may be a prominent sign of several neuromuscular disorders and may be an isolated feature of myasthenia gravis (MG). We describe a patient with isolated neck extensor weakness, eletrophysiological findings suggesting myasthenia gravis and positive MuSK antibodies. This case supports that finding anti-MuSK antibodies may be extremely helpful in dropped head patients and negative acetylcholine receptor antibodies especially if needle EMG does not reveal myopathic or neurogenic patterns.

GH secretion status in myotonic dystrophy.

Frequent endocrine alterations and abnormal growth hormone (GH) secretion have been reported in myotonic dystrophy (MD). To evaluate GH secretion status in MD, GH response to 100 micrograms of growth hormone releasing hormone (GHRH) with or without pyridostigmine pretreatment and its relation with insulin-induced hypoglycemia was investigated in MD patients and compared with normal controls. The mean peak plasma GH response to GHRH was 27.8 +/- 19.2 micrograms/l normal subjects and 11.4 +/- 8.7 micrograms/l in MD patients. In five of seven patients GH reached a mean peak of 12.6 +/- 4.2 micrograms/l after insulin-induced hypoglycemia, compared with 5 +/- 2.8 micrograms/l after GHRH. Conversely, in two patients GH reached a peak of 16.1 and 32 micrograms/l after GHRH, and only 2.5 and 5.3, respectively, after hypoglycemia. Pretreatment with pyridostigmine in nine patients tested potentiated GHRH-induced GH release with a peak of 17.6 +/- 12.5 micrograms/l, compared with 10.05 +/- 6.7 micrograms/l after GHRH alone; IGF-I levels were normal in all patients.

Peripheral neuropathy associated with angioimmunoblastic lymphadenopathy.

A 49-year-old man developed mononeuritis multiplex associated with angioimmunoblastic lymphadenopathy. The biopsy of the sural nerve revealed focal reduction of myelinated fibres and axonal degeneration, as well as perivascular inflammatory infiltrates composed of lymphocytes and plasma cells, exhibiting policlonal immunoglobulin expression, proliferation of blood vessels, thickening of the vessel wall and endothelial hyperplasia. These latter changes are similar to those commonly encountered in the lymph nodes, as well as in other organs, in patients suffering from angioimmunoblastic lymphadenopathy.

[Lumbosacral polyradiculomyelitis caused by cytomegalovirus in a patient with acquired immunodeficiency syndrome]. / Polirradiculomielitis lumbosacra por citomegalovirus en un paciente con síndrome de inmunodeficiencia adquirida.

The case of a HIV positive patient with lumbosacral polyradiculomyelitis by cytomegalovirus (PLS-CMV) is presented. The patient was a homosexual male receiving maintainance treatment with foscarnet for previous corioretinitis by CMV who consulted for paraparesia and sphincter disorders of a 3 week evolution. Neutrophilic pleocytosis and high levels of glucose and proteins were observed on LCR and CMV isolated discarding other entities. The LCR normalized upon treatment with gancyclovir although serious residual paraparesia persisted. PLS-CMV is an infrequent entity of typical clinic and liquoral characteristics. Recognition of the same is important since favorable response depends on early anti-CMV treatment.

18F-FDG PET/CT in the evaluation of POEMS syndrome.

In POEMS syndrome the identification and biopsy of an osteosclerotic lesion or a lymph node typical of Castleman's disease (CD) is essential to establish the diagnosis and plan appropriate treatment. We report four patients in whom the localisation and identification of diagnostic bone lesions or lymphadenopathies were guided by fluorodeoxyglucose positron emission tomography integrated with computerised tomography (FDG PET/CT). FDG PET/CT identified bone lesions not detected with other techniques in one patient, and revealed hypermetabolic characteristics in bone lesions or adenopathies in the others, thus guiding the diagnostic biopsy in those with hypermetabolism. In conclusion, FDG PET/CT may be useful in detecting and selecting bone lesions and lymph nodes for biopsy in patients with suspected POEMS syndrome.

Clinical and molecular analysis of X-linked Charcot-Marie-Tooth disease type 1 in Spanish population.

From 1995 to 2004, 979 families with hereditary peripheral neuropathy were referred to the Genetic Diagnosis Center. Using single-strand conformation analysis (SSCA), the connexin 32 gene was analysed in all the patients from 498 families with sporadic or dominant inheritance with no male-to-male transmission and absence of the 17p2 duplication or deletion. Affected males had pes cavus, distal leg weakness, muscular distal atrophy, areflexia and distal sensory loss. The 106 families in which SSCA revealed abnormal migration electrophoresis were directly sequenced. We found 34 families (59 patients) with mutations in connexin 32 gene. In electrophysiological studies, 58.8% families presented slow and 14.7% intermediate nerve conduction velocities. Molecular findings revealed that codon 164 (29.4 +/- 15.3%) and the second extracellular (EC2) domain (44.1 +/- 16.6%) were the most frequently affected codon and domain of the connexin 32. Six novel mutations, Leu39fs, Glu47Gly, His153fs, Cys179Tyr, Cys201Phe and Ser211fs, were found in our study.

Development of non-pyramidal neurons in the rat sensorymotor cortex during the fetal and early postnatal periods.

The development of non-pyramidal neurons was studied in the rat sensorymotor cortex during the fetal and early postnatal periods with Golgi's method. Additional data of the early stages were obtained using autoradiography and electron microscopy. Horizontal neurons in the marginal layer were found from the 15th postconceptional (pc.) day (cellular birthday: 13th-15th pc. day). Horizontal neurons in the inner margin of the early cortical plate were found from the 16th pc. day (cellular birthday: 14th-16th pc. day). Coarse cell profiles were seen with Golgi's method, but, under electron microscope, increased numbers of organelles were observed in these cells, as compared to those of the cortical plate. From the 17th day of gestational age to the moment of birth, a small number of non-pyramidal neurons were stained with Golgi's method, including horizontal, stellate, and neurogliform neurons, at different levels of the cortical plate. The greatest development of the non-pyramidal system was observed during the second postnatal week, while the greatest increase of dendritic branches and synaptic spines was observed during the third and fourth weeks. This pattern is similar to that observed in the pyramidal system, but an ascending gradient was not observed.

Leptin after IGF-I generation test in a patient with hypopituitarism and myotonic dystrophy disease.

A 54-years-old woman diagnosed of myotonic dystrophy (MyD) with past medical history of massive postpartum haemorrhage at age 28 and panhypopituitarism was studied. BMI and body composition were determined and we determined baseline serum IGF-I, IGFBP3, insulin and leptin levels and after the IGF-I generation test performed after the GH administration of 0.1 U/kg/day s.c each evening for 4 days. As expected the patient had lower baseline IGF-I and IGFBP3 with high insulin and leptin levels. After IGF-I generation test, IGF-I, IGFBP3 and insulin levels increases without changes in body composition and leptin levels. In the current study, high leptin baseline levels may reflect the hyperinsulinism action over the adipose tissue in MyD and the effect of hypopituitarism over leptin regulation. After 4 days of GH administration, we demonstrated the lack of a modulatory role on leptin levels of GH and acute insulin increase, and a direct effect of GH on leptin can be excluded.

[Centronuclear myopathy]. / Miopatía centronuclear.

A 19 year-old patient, second child of a non consanguinous marriage, was evaluated because of the patient progressive mental retardation and muscular weakness from infancy. Six maternal uncles non had died of unknown cause in the first year of life, and his mother had 3 spontaneous miscarriages; the two sisters of the patient were healthy. Clinical examination demonstrated a severe mental retardation, discrete proximal muscular weakness as well as universal areflexia. The muscular enzymes were elevated and the electrophysiologic study showed normal neurographic parameters and abundant generalized spontaneous activity with a mixed type contraction pattern. Histologic examination of the muscle was diagnosed as myopathy with atrophy of type I fibers and central nuclei and upon cranial nuclear magnetic resonance (NMR) images suggestive of perinatal hypoxic-ischemic encephalopathy were observed.

[Dysphagia as the only manifestation of inclusion body myositis]. / Disfagia como única manifestación de una miositis por cuerpos de inclusión.

We report a 72-year-old woman with dysphagia as the only manifestation of inclusion body myositis (IBM). Although electrophysiological examination revealed subclinical abnormalities in limb muscles, dysphagia was the only symptom 4 years after the onset of the disease. Muscle biopsy showed rimmed vacuoles and cytoplasmic inclusions together with lymphocytic inflammation. IBM must be included in the differential diagnosis of isolated dysphagia.

Apoptosis is not the mechanism of cell death of muscle fibers in human muscular dystrophies and inflammatory myopathies.

Muscle biopsies from patients affected by muscular dystrophies and polymyositis were processed with the method of in situ labeling of nuclear DNA fragmentation in order to assess whether apoptosis occurs in these diseases. Apoptotic nuclei were seen in the mononuclear cell infiltrates in inflammatory myopathies but not in dying muscle fibers, thus confirming the general opinion that death of muscle fibers in human diseases is not produced by a mechanism of apoptosis.

[Neuropathy by n-hexanes: a generalized disorder of the intermediate filaments]. / Neuropatía por n-hexanos: un trastorno generalizado de los filamentos intermedios.

BACKGROUND: Chronic inhalation of glues containing n-hexanes produces neurofilament (NF) accumulation which induces sensory-motor polyneuropathy. In vitro assays have shown this toxic substance causes intermediate filaments (IF) aggregation in non-neuronal cells. OBJECTIVE: To describe intermediate filament changes in human pathology due to n-hexanes. PATIENTS AND METHODS: Sural nerve and skin biopsy samples from 2 patients who suffered from a severe sensory-motor polyneuropathy after prolonged inhalation of glue containing n-hexane were examined with electron microscopy and vimentin and phosphorylated NF immunocytochemistry. RESULTS: Abnormal accumulations of NF and NF-immunoreactive products occurred in nerve fibers and increased numbers of fibrils were observed in endoneurial endothelial cells of the sural nerve. In addition, abnormal vimentin-immunoreactive deposition was seen in fibroblasts and capillaries of the skin. The present results suggest that high doses of n-hexane cause a diffuse IF disorder in a similar form as occurs in giant axonal neuropathy. CONCLUSION: IF aggregation can occur in non-neuronal cells in humans, as has been previously proved in in vitro experiments. The presence of IF accumulations in Schwann cells, as seen in the ultrastructural examination, together with the electrophysiological findings showing an early decrease of sensory and motor nerve conduction velocities, suggests the existence of a primary myelinic disorder associated with axonal damage.