Mutation of the slow myosin heavy chain rod domain underlies hyaline body myopathy.

OBJECTIVE: To identify the gene and specific mutation underlying hyaline body myopathy in the family studied. METHODS: A microsatellite-based whole genome scan was performed. Linkage analysis assumed autosomal dominant inheritance and equal allele frequencies. A candidate gene approach within the linked interval and direct sequencing were used for mutation detection. RESULTS: Initial analysis indicated a maximum lod score of 3.01 at D14S1280. High-density mapping surrounding the linked locus was performed. Multipoint analysis showed that the linked region with a maximum lod score of 3.01 extended from D14S742 to D14S608 with a peak non-parametric linkage (NPL) score of 3.75 at D14S608. The myosin heavy chain genes MYH6 and MYH7 map to the region between D14S742 and D14S1280. Sequence analysis of the coding regions of MYH7 revealed an A-->T transversion at nucleotide position 25596 (M57965) resulting in a histidine-to-leucine amino acid change at residue 1904 (H1904L). CONCLUSION: Pathogenicity of the MYH7 H1904L mutation most likely results from disruption of myosin heavy chain assembly or stability of the sarcomeric protein. The MYH7 tail domain mutation results in an inclusion body myopathy with an apparent absence of hypertrophic cardiomyopathy usually associated with mutations of this gene.

Autosomal dominant hyaline body myopathy: clinical variability and pathologic findings.

OBJECTIVE: To report clinical, morphologic, and immunohistochemical studies on autosomal dominant, clinically nonprogressive, and not previously described progressive forms of hyaline body (HB) myopathy (HBM) in a Saudi Arabian kindred. RESULTS: Muscle biopsies from four patients showed HB in type 1 fibers; they were positive for ATPase at pH 4.3/4.6 and for heavy chain slow myosin (HCSM); some HB were HCSM negative. HB were nonreactive for alphaB-crystallin, ubiquitin, tropomyosin, actins, desmin, and components of sarcolemma. Ultrastructurally, HB were granular and filamentous or amorphous, often with fragments of sarcomeres, and surrounded by a zone of sarcomeric disorganization. All biopsies showed "myopathic" changes, angulated neurogenic fibers, and fiber type grouping. There was no correlation between HB and course of disease; the progressive cases displayed more severe myopathic features. CONCLUSIONS: Formation of hyaline bodies in hyaline body myopathy is associated with either myolysis or defective incorporation of heavy chain slow myosin into the cytoskeleton. Hyaline bodies very likely contain additional unidentified proteins. Neurogenic factors are also involved in the hyaline body myopathy pathogenesis.

Pitfalls in cerebrospinal fluid test for the diagnosis of neurosyphilis.

OBJECTIVE: To determine the usefulness of cerebrospinal fluid tests in the diagnosis of neurosyphilis. METHODS: Two hundred and seven cerebrospinal fluid-Venereal Disease Research Laboratories tests were performed at King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia between 1992 and 1997. The records of 14 cases with progressive neurological disease and reactive serum fluorescent treponemal absorbent antibodies or treponemal pallidum hemagglutination test were reviewed for clinical presentation, cerebrospinal fluid analysis and Venereal Disease Research Laboratories, neuro-imaging abnormalities and compatibility with the diagnosis of neurosyphilis. The diagnosis of neurosyphilis was made if the patient had reactive serum fluorescent treponemal absorbent antibodies or treponemal pallidum hemagglutination, history of progressive neurological disease and increased cerebrospinal fluid cells or protein. RESULTS: None of the 207 cerebrospinal fluid-Venereal Disease Research Laboratories tests were reactive. The diagnosis of neurosyphilis was made in 10 out of 14 cases with progressive neurological disease and reactive serum rapid plasma reagin, fluorescent treponemal absorbent antibodies and treponemal pallidum hemagglutination. CONCLUSION: We conclude that if reactive cerebrospinal fluid-Venereal Disease Research Laboratories is required to confirm or diagnose neurosyphilis, most cases will be overlooked.

Pitfalls in cerebrospinal fluid test for the diagnosis of neurosyphilis.

OBJECTIVE: To determine the usefulness of cerebrospinal fluid tests in the diagnosis of neurosyphilis. METHODS: Two hundred and seven cerebrospinal fluid-Venereal Disease Research Laboratories tests were performed at King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia between 1992 and 1997. The records of 14 cases with progressive neurological disease and reactive serum fluorescent treponemal absorbent antibodies or treponemal pallidum hemagglutination test were reviewed for clinical presentation, cerebrospinal fluid analysis and Venereal Disease Research Laboratories, neuro-imaging abnormalities and compatibility with the diagnosis of neurosyphilis. The diagnosis of neurosyphilis was made if the patient had reactive serum fluorescent treponemal absorbent antibodies or treponemal pallidum hemagglutination, history of progressive neurological disease and increased cerebrospinal fluid cells or protein. RESULTS: None of the 207 cerebrospinal fluid-Venereal Disease Research Laboratories tests were reactive. The diagnosis of neurosyphilis was made in 10 out of 14 cases with progressive neurological disease and reactive serum rapid plasma reagin, luorescent treponemal absorbent-absorbent antibodies and treponemal pallidum hemagglutination. CONCLUSION: We conclude that if reactive cerebrospinal fluid-Venereal Disease Research Laboratories is required to confirm or diagnose neurosyphilis, most cases will be overlooked.

Neurotrophin 4/5 immunoassay: identification of sources of errors for the quantification of neurotrophins.

Neurotrophin 4/5 (NT4/5) is the least understood member of the mammalian neurotrophin family. Precise and reliable determinations of endogenous NT4/5 levels are essential to understand its physiology. Immunoassay has been used for neurotrophin quantification for over three decades. However, this apparently simple task has proved elusive: conflicting results have long been recognized for nerve growth factor (NGF; up to 10000-fold variations in serum values have been reported in the literature) and more recently, for brain-derived neurotrophic factor (as much as 50-fold reported in rat hippocampus). Reasons for these variations have been extensively investigated by researchers, but rarely explained. During the development of our NT4/5 immunoassay, we discovered that false positive reactions resulted when tissues were extracted and assayed under certain conditions. In this study, we examined the major factors that adversely affect the quantification of NT4/5. Tissue samples from Sprague-Dawley rats were dissected and extracted in a range of buffers. The assay was performed on 96 well vinyl plates using sheep anti-NT4/5 immunoglobulin (Ig) as the capture (first) antibody, and a monoclonal anti-NT4/5 as the detector (second) antibody, followed by anti-mouse IgG (third) conjugated with peroxidase or alkaline phosphatase from several manufacturers. Our results show that: (1) tissue extraction at high or low pH, a method previously found to increase the measurable amount of NGF, produced greater false positive results for NT4/5 when compared with extraction at neutral pH; (2) the most significant source of error derived from the use of conjugated antibodies capable of reacting with molecules within tissue extracts which bind to the plate, even after thorough blocking; and (3) quantification is also significantly affected by both the standards used and the ability of the antibodies to react with these standards. Our findings indicate that the precise determination of neurotrophin levels requires quality reagents and the optimization of extraction conditions for each neurotrophin. The use of a two - rather than a three - antibody assay system avoids most of the interactions which give rise to false positive reactions.

Miyoshi myopathy in Saudi Arabia: clinical, electrophysiological, histopathological and radiological features.

Miyoshi myopathy (MM) is a rare autosomal recessive distal myopathy linked to chromosome 2p12-14 that has not been described in Saudi Arabia. A Saudi family with five siblings aged 3-25 years, an unrelated 18-year-old woman and a 40-year-old man with MM were identified. All patients underwent a neurological examination, serum chemistry, electromyography and MRI of the legs. Four patients underwent a muscle biopsy that was processed for routine enzyme histochemistry and immunocytochemical analyses for dystrophin and adhalin (alpha-sarcoglycan). The two sporadic and two familial cases showed classic findings of MM, including early adult onset, preferential involvement of gastrocnemius muscles, markedly elevated serum creatine kinase levels and dystrophic-appearing muscle without vacuoles. Magnetic resonance imaging revealed selective involvement of the posterior compartment muscles and myoedema by STIR sequences. The remaining three familial cases had elevated serum creatine kinase levels and two also had early myopathic findings by EMG suggestive of MM.

Inclusion body myositis in HIV-1 and HTLV-1 infected patients.

Sporadic inclusion body myositis (IBM) is the most common inflammatory myopathy affecting patients over the age of 50 years. Dysimmune and degenerative aetiologies have been postulated, but viral infections have not been associated with the disease. Two HIV-I (human immunodeficiency virus type 1) infected men and one woman infected with HTLV-1 (human T cell leukaemia virus type 1) developed progressive proximal muscle weakness unrelated to antiretroviral therapy. Their muscle biopsies were studied by light and electron microscopy, by immunocytochemistry to determine the expression of major histocompatibility complex (MHC) molecules and identify the type of infiltrating cells and T cell receptor (TCR) subunits, and by reverse transcription-polymerase chain reaction (RT-PCR) and single or double immunocytochemistry to search for retrovirally infected endomysial cells. The clinical features were consistent with sporadic IBM. The muscle biopsies showed primary endomysial inflammation, red-rimmed vacuoles, amyloid deposits, eosinophilic inclusions, and small round fibres in groups, all diagnostic of IBM. The muscle fibres expressed MHC class-1 antigens and were invaded primarily by CD8+ T-lymphocytes preferentially bearing TCR V beta 5.1 and V beta 13 chains. The HIV-1 or HTLV-1 antigens were detected only on endomysial macrophages on or around muscle fibres, but not within the muscle fibres. We conclude that IBM occurs in HIV-1 and HTLV-1 infected individuals and has a clinical, histological and immunological pattern identical to sporadic IBM in the non-retrovirally infected patients. Retroviruses do not directly infect the muscle, but persistent retroviral infections may provide superantigenic stimulation and trigger an endomysial inflammatory response identical to that occurring in sporadic IBM.

Neuropathies in HIV infection.

Peripheral neuropathies represent the most common neurological manifestation in patients infected with HIV infection occurring either early in the infection or during the course of the illness. They present as acute or chronic demyelinating neuropathies (Guillain-Barré syndrome or chronic inflammatory demyelinating polyneuropathy), mononeuritis multiplex, ganglioneuronitis, cytomegalovirus-related polyradiculoneuropathy, autonomic neuropathy or distal painful sensory neuropathy. They are multifactorial in aetiology. Their putative cause (viral, autoimmune, toxic, nutritional, co-infections) are often dictated by the stage of the underlying HIV disease. The virus, which is not found within ganglionic neurones or Schwann cells but only within the endoneurial macrophages, may generate a tissue-specific autoimmune attack by secretion of cytokines that promote trafficking of activated T cells and macrophages within the endoneurial parenchyma. The wide use of the neurotoxic antiretroviral nucleoside analogues ddC, ddI, d4T and 3TC, exacerbate or trigger subclinical neuropathy in many of these patients.

Early features of zidovudine-associated myopathy: histopathological findings and clinical correlations.

Zidovudine-induced myopathy is characterized by reversible muscle weakness, wasting, myalgia, fatigue, and elevated creatine kinase (CK). Some zidovudine-treated patients with normal muscle strength experience excessive fatigue, myalgia, or transient mild CK elevations that improve when zidovudine is stopped. To determine the cause of these symptoms, we studied 13 physically fit, HIV-infected men who developed fatigue, myalgia, and reduced endurance, while taking zidovudine for a mean period of 20 months (2-39 months), with neurological evaluation and muscle biopsy processed for enzyme histochemistry and electron microscopy (EM). All subjects had normal muscle strength. In 6 of the 13 patients, muscle biopsies were normal by enzyme histochemistry. EM, however, demonstrated proliferation of normal or abnormal mitochondria, and increased amounts of lipid, glycogen, and lipofuscin. Electromyographic (EMG) studies (5/5) and serum CK (6/6) were normal. The other 7 individuals had signs of moderate to severe mitochondrial abnormalities shown by both light microscopy and EM, characterized by severe destruction, vacuolization, and rare paracrystalline inclusions. Most had elevated CK (4 out of 7) and normal EMG (5 out of 7). The severity of morphological abnormalities did not correlate with duration of HIV infection, zidovudine therapy, or zidovudine dosage. We conclude that in zidovudine-treated patients, symptoms of fatigue, myalgia, reduced endurance, and exercise intolerance represent early signs of zidovudine-induced mitochondriotoxicity, which causes an energy shortage within the muscle fibers even when muscle strength is still normal. Zidovudine, a DNA chain terminator, results in overt myopathy when a critical threshold of molecular, histological, and biochemical dysfunction of mitochondria is crossed, which seems to vary between individuals.

Effect of high-dose intravenous immunoglobulin on amyotrophic lateral sclerosis and multifocal motor neuropathy.

OBJECTIVE: To determine if high-dose intravenous immunoglobulin therapy is effective in improving muscle strength or in arresting the pace of disease progression in patients with rapidly progressive amyotrophic lateral sclerosis. DESIGN: An open-label pilot study of intravenous infusions of high-dose immunoglobulin administered once a month for 3 months in nine patients with classic amyotrophic lateral sclerosis. Selected patients had a rapidly progressive course with signs of worsening noticeably evident every 6 weeks prior to therapy. A patient with multifocal motor neuropathy with conduction block that presented as a lower motor neuron syndrome was concurrently treated to document the efficacy of the same preparation of immunoglobulin in a potentially treatable disease that simulates lower motor neuron syndrome. The efficacy of high-dose intravenous immunoglobulin infusions was assessed by objective measurement of maximum voluntary isometric contraction in all muscle groups of two limbs before and after therapy. SETTING: The Clinical Center of the National Institutes of Health, Bethesda, Md. RESULTS: All patients with amyotrophic lateral sclerosis worsened during the study. By the end of the third month, their mean total muscle scores (megascores) had declined by 71.2 points, from a mean of 369.7 (range, 200 to 605) to 298.5 (range, 130 to 552) points. The pace of progression did not change during the 4-month observation period. In contrast, the patient with multifocal motor neuropathy responded to intravenous immunoglobulin therapy and increased his megascores by 146 points after 3 months. The GM1 antibody titers were normal in all the patients. CONCLUSIONS: High-dose intravenous immunoglobulin, a prohibitively expensive drug, has no apparent therapeutic role in improving the symptoms or arresting the pace of progression in patients with amyotrophic lateral sclerosis. In contrast, multifocal motor neuropathy is an immunopathologically different disease that responds to intravenous immunoglobulin therapy.

Aseptic meningitis associated with high-dose intravenous immunoglobulin therapy: frequency and risk factors.

OBJECTIVE: Intravenous immunoglobulin is widely used to treat various autoimmune disorders. After observing instances of aseptic meningitis in treated patients, we studied the frequency and associated risk factors for aseptic meningitis in patients treated with high-dose intravenous immunoglobulin. DESIGN: Retrospective analysis of a prospective cohort study. SETTING: Tertiary research referral center. PATIENTS: 54 consecutive patients with various immune-related neuromuscular diseases participating in ongoing therapeutic trials of high-dose (2 g/kg) intravenous immunoglobulin. MEASUREMENTS: Analysis of patient records for evidence of aseptic meningitis, associated risk factors, penetration of serum IgG into the cerebrospinal fluid, and clearance of cerebrospinal fluid IgG. RESULTS: Of 54 patients, 6 (11%; 95% CI, 4% to 23%) developed aseptic meningitis within 24 hours after completion of the infusions. Symptoms, lasting 3 to 5 days, included severe headache, meningismus, photophobia, and fever. Cerebrospinal fluid showed pleocytosis in 4 patients (leukocyte count as high as 1169 x 10(6)/L in one patient), eosinophilia in 3 patients, and IgG elevation in all patients (as great as 7 times the upper limit of normal in one patient). Repeat cerebrospinal fluid and serum studies after 24 hours showed a 46% cerebrospinal fluid IgG clearance compared with an 11% clearance of serum IgG in one patient. Cerebrospinal fluid cultures were negative. Aseptic meningitis developed in 4 of 8 patients (50%; CI, 16% to 84%) with a history of migraine but in only 2 of 46 (4%; CI, 0.5% to 15%) patients without such a history (P = 0.003). Aseptic meningitis recurred in patients who had migraine despite the use of different commercial intravenous immunoglobulin preparations and slower rates of infusion. CONCLUSION: Aseptic meningitis develops in patients receiving high-dose intravenous immunoglobulin therapy. Patients with a history of migraine are more likely to develop aseptic meningitis while receiving intravenous immunoglobulin therapy, regardless of the type of commercial preparation or the infusion rate. Possible inciting factors include the IgG itself, various stabilizing products within each of the preparations, cytokine release triggered by the therapy, or cerebrovascular sensitivity in migraineurs.