Metabolic shift underlies recovery in reversible infantile respiratory chain deficiency.

Reversible infantile respiratory chain deficiency (RIRCD) is a rare mitochondrial myopathy leading to severe metabolic disturbances in infants, which recover spontaneously after 6-months of age. RIRCD is associated with the homoplasmic m.14674T>C mitochondrial DNA mutation; however, only ~ 1/100 carriers develop the disease. We studied 27 affected and 15 unaffected individuals from 19 families and found additional heterozygous mutations in nuclear genes interacting with mt-tRNAGlu including EARS2 and TRMU in the majority of affected individuals, but not in healthy carriers of m.14674T>C, supporting a digenic inheritance. Our transcriptomic and proteomic analysis of patient muscle suggests a stepwise mechanism where first, the integrated stress response associated with increased FGF21 and GDF15 expression enhances the metabolism modulated by serine biosynthesis, one carbon metabolism, TCA lipid oxidation and amino acid availability, while in the second step mTOR activation leads to increased mitochondrial biogenesis. Our data suggest that the spontaneous recovery in infants with digenic mutations may be modulated by the above described changes. Similar mechanisms may explain the variable penetrance and tissue specificity of other mtDNA mutations and highlight the potential role of amino acids in improving mitochondrial disease.

Clinicogenetic lessons from 370 patients with autosomal recessive limb-girdle muscular dystrophy.

Limb-girdle muscular dystrophies (LGMD) are a group of genetically heterogeneous disorders characterized by predominantly proximal muscle weakness. We aimed to characterize epidemiological, clinical and molecular data of patients with autosomal recessive LGMD2/LGMD-R in Brazil. A multicenter historical cohort study was performed at 13 centers, in which index cases and their affected relatives' data from consecutive families with genetic or pathological diagnosis of LGMD2/LGMD-R were reviewed from July 2017 to August 2018. Survival curves to major handicap for LGMD2A/LGMD-R1-calpain3-related, LGMD2B/LGMD-R2-dysferlin-related and sarcoglycanopathies were built and progressions according to sex and genotype were estimated. In 370 patients (305 families) with LGMD2/LGMD-R, most frequent subtypes were LGMD2A/LGMD-R1-calpain3-related and LGMD2B/LGMD-R2-dysferlin-related, each representing around 30% of families. Sarcoglycanopathies were the most frequent childhood-onset subtype, representing 21% of families. Five percent of families had LGMD2G/LGMD-R7-telethonin-related, an ultra-rare subtype worldwide. Females with LGMD2B/LGMD-R2-dysferlin-related had less severe progression to handicap than males and LGMD2A/LGMD-R1-calpain3-related patients with truncating variants had earlier disease onset and more severe progression to handicap than patients without truncating variants. We have provided paramount epidemiological data of LGMD2/LGMD-R in Brazil that might help on differential diagnosis, better patient care and guiding future collaborative clinical trials and natural history studies in the field.

Phenotypic Variability of Dystrophinopathy Symptomatic Female Carriers.

BACKGROUND: Dystrophinopathies are X-linked muscular dystrophies characterized by pathogenic mutations in the dystrophin gene. Symptomatic dystrophinopathy female carriers may present with limb-girdle weakness. The diagnosis may be challenging in the absence of affected male relatives. We aimed to describe the phenotypic variability in a series of molecular-confirmed female dystrophinopathy patients. METHODS: This is a retrospective analysis of medical records from 1997 to 2015. RESULTS: Ten female dystrophinopathy patients were selected, two with unusual phenotypes: one with early joint contractures muscular dystrophy and the other with very late onset myopathy. Muscle imaging studies demonstrated predominant asymmetric fat replacement. Muscle biopsy immunohistochemistry demonstrated clear mosaic pattern in two cases and only subtle reduction of dystrophin intensity in three. CONCLUSIONS: Adequate diagnosis is fundamental for genetic counseling and cardiologic follow-up. Female patients with dystrophinopathy may present unusual phenotypes such as early contractures and very late onset myopathy.

Limb girdle muscular dystrophy type 2G with myopathic-neurogenic motor unit potentials and a novel muscle image pattern.

BACKGROUND: Limb girdle muscular dystrophy type 2G (LGMD2G) is a subtype of autosomal recessive muscular dystrophy caused by mutations in the telethonin gene. There are few LGMD2G patients worldwide reported, and this is the first description associated with early tibialis anterior sparing on muscle image and myopathic-neurogenic motor unit potentials. CASE PRESENTATION: Here we report a 31 years old caucasian male patient with progressive gait disturbance, and severe lower limb proximal weakness since the age of 20 years, associated with subtle facial muscle weakness. Computed tomography demonstrated soleus, medial gastrocnemius, and diffuse thigh muscles involvement with tibialis anterior sparing. Electromyography disclosed both neurogenic and myopathic motor unit potentials. Muscle biopsy demonstrated large groups of atrophic and hypertrophic fibers, frequent fibers with intracytoplasmic rimmed vacuoles full of autophagic membrane and sarcoplasmic debris, and a total deficiency of telethonin. Molecular investigation identified the common homozygous c.157C > T in the TCAP gene. CONCLUSION: This report expands the phenotypic variability of telethoninopathy/ LGMD2G, including: 1) mixed neurogenic and myopathic motor unit potentials, 2) facial weakness, and 3) tibialis anterior sparing. Appropriate diagnosis in these cases is important for genetic counseling and prognosis.

Central Core Disease: Facial Weakness Differentiating Biallelic from Monoallelic Forms.

Central Core Disease (CCD) is a genetic neuromuscular disorder characterized by the presence of cores in muscle biopsy. The inheritance has been described as predominantly autosomal dominant (AD), and the disease may present as severe neonatal or mild adult forms. Here we report clinical and molecular data on a large cohort of Brazilian CCD patients, including a retrospective clinical analysis and molecular screening for RYR1 variants using Next-Generation Sequencing (NGS). We analyzed 27 patients from 19 unrelated families: four families (11 patients) with autosomal dominant inheritance (AD), two families (3 patients) with autosomal recessive (AR), and 13 sporadic cases. Biallelic RYR1 variants were found in six families (two AR and four sporadic cases) of the 14 molecularly analyzed families (~43%), suggesting a higher frequency of AR inheritance than expected. None of these cases presented a severe phenotype. Facial weakness was more common in biallelic than in monoallelic patients (p = 0.0043) and might be a marker for AR forms. NGS is highly effective for the identification of RYR1 variants in CCD patients, allowing the discovery of a higher proportion of AR cases with biallelic mutations. These data have important implications for the genetic counseling of the families.

Muscle fat replacement and modified ragged red fibers in two patients with reversible infantile respiratory chain deficiency.

Reversible infantile respiratory chain deficiency is a severe neonatal mitochondrial myopathy that resolves spontaneously. It is caused by the homoplasmic m.14674T>C mtDNA mutation and additional nuclear variants in genes interacting with mt-tRNAGlu have been detected in some patients. We present detailed clinical, imaging, and muscle biopsy findings in a boy and a girl with neonatal hypotonia, feeding difficulties, lactic acidosis, and ragged red fibers. Both patients show fat replacement on muscle imaging, which was mild in the boy, but severe in the girl, affecting mostly the posterior leg muscles. In addition to the homoplasmic m.14674T>C, both patients carried heterozygous variants in QRSL1 (c. 686T>G; p.Val299Gly) and EARS2 (c.358C>T; p.Arg120Trp), respectively. It is very important to recognize the clinical and morphological signs of reversible infantile respiratory chain deficiency as patients should receive intensive supportive care in the first 6 months of life. Understanding the mechanism of the spontaneous recovery may lead to novel therapeutic perspectives in other mitochondrial diseases.

Dominant or recessive mutations in the RYR1 gene causing central core myopathy in Brazilian patients.

Central Core Disease (CCD) is an inherited neuromuscular disorder characterized by the presence of cores in muscle biopsy. CCD is caused by mutations in the RYR1 gene. This gene encodes the ryanodine receptor 1, which is an intracellular calcium release channel from the sarcoplasmic reticulum to the cytosol in response to depolarization of the plasma membrane. Mutations in this gene are also associated with susceptibility to Malignant Hyperthermia (MHS). In this study, we evaluated 20 families with clinical and histological characteristics of CCD to identify primary mutations in patients, for diagnosis and genetic counseling of the families. We identified variants in the RYR1 gene in 19/20 families. The molecular pathogenicity was confirmed in 16 of them. Most of these variants (22/23) are missense and unique in the families. Two variants were recurrent in two different families. We identified six families with biallelic mutations, five compound heterozygotes with no consanguinity, and one homozygous, with consanguineous parents, resulting in 30% of cases with possible autosomal recessive inheritance. We identified seven novel variants, four of them classified as pathogenic. In one family, we identified two mutations in exon 102, segregating in cis, suggesting an additive effect of two mutations in the same allele. This work highlights the importance of using Next-Generation Sequencing technology for the molecular diagnosis of genetic diseases when a very large gene is involved, associated to a broad distribution of the mutations along it. These data also influence the prevention through adequate genetic counseling for the families and cautions against malignant hyperthermia susceptibility.

Early-onset coenzyme Q10 deficiency associated with ataxia and respiratory chain dysfunction due to novel pathogenic COQ8A variants, including a large intragenic deletion.

Coenzyme Q10 (CoQ10) deficiency is a clinically and genetically heterogeneous subtype of mitochondrial disease. We report two girls with ataxia and mitochondrial respiratory chain deficiency who were shown to have primary CoQ10 deficiency. Muscle histochemistry displayed signs of mitochondrial dysfunction-ragged red fibers, mitochondrial paracrystalline inclusions, and lipid deposits while biochemical analyses revealed complex II+III respiratory chain deficiencies. MRI brain demonstrated cerebral and cerebellar atrophy. Targeted molecular analysis identified a homozygous c.1015G>A, p.(Ala339Thr) COQ8A variant in subject 1, while subject 2 was found to harbor a single heterozygous c.1029_1030delinsCA variant predicting a p.Gln343_Val344delinsHisMet amino acid substitution. Subsequent investigations identified a large-scale COQ8A deletion in trans to the c.1029_1030delinsCA allele. A skin biopsy facilitated cDNA studies that confirmed exon skipping in the fibroblast derived COQ8A mRNA transcript. This report expands the molecular genetic spectrum associated with COQ8A-related mitochondrial disease and highlights the importance of thorough investigation of candidate pathogenic variants to establish phase. Rapid diagnosis is of the utmost importance as patients may benefit from therapeutic CoQ10 supplementation.

Limb Length Discrepancy on an 11-Month-Old Boy with Osteoid Osteoma.

Osteoid osteoma is a benign bone tumor that frequently occurs between the ages of 10 and 25 years old; in about 80% of the patients, it is associated with intense pain. The present article describes the case of an 11-month-old infant with claudication, right lower limb shortening, and painless right leg volume increase. Image studies demonstrated an osteolytic lesion with small ossifications within, involved by cortical thickening of the right tibial diaphysis. The diagnostic hypotheses were osteoid osteoma, chronic osteomyelitis (Brodie abscess), Ewing sarcoma, and Langerhans cell histiocytosis. Microorganism cultures were negative and the histopathological exam demonstrated osteoid osteoma. The present report expands the knowledge on osteoid osteoma as a cause of painless limping and lower limb shortening in infancy. The early differential diagnosis is important, as surgical excision is curative and prevents further complications.

LMNA-Related Muscular Dystrophy with Clinical Intrafamilial Variability.

The LMNA gene is associated to a huge broad of phenotypes, including congenital Emery-Dreifuss muscular dystrophy and late-onset LMNA-related muscular dystrophy. In these forms, muscle weakness, contractures, and cardiac impairment are common. In an autosomal dominant pedigree including 5 affected patients, NGS molecular analysis performed in 6 relatives identifies the heterozygous c.1129C>T p.Arg377Cys variant in the exon 6 of the LMNA gene in three of them. Clinical, laboratorial, imaging investigation of these affected patients showed a significant clinical variability: the father presented subclinical imaging muscular dystrophy masqueraded as radiculopathy. One of his sons presented cardiac arrhythmia, muscular weakness, elbow contractures, and intranuclear pseudoinclusions on muscle biopsy. A second son presented only decreased tendon reflexes. Two other brothers presenting myalgia and cramps were not carriers of the same mutation in the LMNA gene. Early diagnosis, considering these variable phenotype and genotype, is important for genetic counseling, as well as cardiac, and rehabilitation management.

The relative frequency of common neuromuscular diagnoses in a reference center.

The diagnostic procedure in neuromuscular patients is complex. Knowledge of the relative frequency of neuromuscular diseases within the investigated population is important to allow the neurologist to perform the most appropriate diagnostic tests. OBJECTIVE: To report the relative frequency of common neuromuscular diagnoses in a reference center. METHODS: A 17-year chart review of patients with suspicion of myopathy. RESULTS: Among 3,412 examinations, 1,603 (46.98%) yielded confirmatory results: 782 (48.78%) underwent molecular studies, and 821 (51.21%) had muscle biopsies. The most frequent diagnoses were: dystrophinopathy 460 (28.70%), mitochondriopathy 330 (20.59%), spinal muscular atrophy 158 (9.86%), limb girdle muscular dystrophy 157 (9.79%), Steinert myotonic dystrophy 138 (8.61%), facioscapulohumeral muscular dystrophy 99 (6.17%), and other diagnoses 261 (16.28%). CONCLUSION: Using the presently-available diagnostic techniques in this service, a specific limb girdle muscular dystrophy subtype diagnosis was reached in 61% of the patients. A neuromuscular-appropriate diagnosis is important for genetic counseling, rehabilitation orientation, and early treatment of respiratory and cardiac complications.

Diagnosis of mycosis fungoides: a comparative immunohistochemical study of T-cell markers using a novel anti-CD7 antibody.

Mycosis fungoides (MF) is the most common form of primary cutaneous T-cell lymphoma. In its early stage it may mimic benign dermatoses both on a clinical and histologic basis. MF usually expresses CD3 and CD4 (T-cell) markers. CD7 is expressed on about 90% of CD4 T cells and is often deficient on malignant T cells. Thus, CD7 may be useful in evaluating the nature of dermal lymphoid infiltrates. The aim of this study was to evaluate the usefulness of immunohistochemical detection of T-cell markers on paraffin-embedded sections, CD3 and CD7 (clone CBC.37), in the differential diagnosis of MF and benign dermatoses. Forty-two patients with diffuse dermal T-lymphocytic infiltrates were selected. Previous clinicopathologic correlation and follow-up had established the diagnosis of MF in 31 patients and benign dermatoses in 11. The mean value of stained cells in MF was 86.45% for CD3 and 53.09% for CD7 (P<0.001); in benign dermatoses it was 79.09% for CD3 and 73.63% for CD7 (P=0.669). CD7 immunolabeling was significantly lower in the MF group (P=0.048). A semiquantitative evaluation revealed a considerable loss of CD7 immunolabeling in comparison with CD3 in patients with MF. The authors conclude that CD7 study may represent a valuable tool in the distinction between inflammation and neoplasia in T-lymphoproliferative skin disorders.

Prostatic atrophy: evidence for a possible role of local ischemia in its pathogenesis.

Prostatic atrophy may be histologically and at ultrasound similar to adenocarcinoma causing diagnostic confusion, its frequency increases with age but the etiopathogenesis is unknown. Based on a systematic study in autopsies previously done by one of us, ischemia due to local intense arteriosclerosis seems to be a potential factor for its pathogenesis. Absent blood flow in areas of prostatic atrophy might be a further evidence for a possible role of ischemia. From a total of 298 patients biopsied and studied by gray-scale and color Doppler transrectal ultrasound in the period 1998 to 2001, 33 patients had suspicious lesions (37 hypoechoic nodules and 3 heterogeneous lesions) showing prostatic atrophy as the only diagnosis on all these biopsied lesions. Adenocarcinoma, high-grade intraepithelial neoplasia or other atypical lesions were absent in all patients. On color Doppler the suspicious areas showed absent flow in 24/40 (60%), present flow in 12/40 (30%), and increased flow in 4/40 (10%) of the lesions. Absent flow in the majority of the lesions studied may be a further evidence for a possible role of local ischemia in the etiopathogenesis of prostatic atrophy.

Reassessment of diagnostic criteria in cutaneous lymphocytic infiltrates.

CONTEXT: Non-specific lymphocytic infiltrates of the skin pose difficulties in daily practice in pathology. There is still a lack of pathognomonic signs for the differential diagnosis between benign and malignant lymphocytic infiltrates. OBJECTIVE: To evaluate the morphological and immunohistochemical profile of lymphocytic infiltrations of the skin according to clinical outcome. TYPE OF STUDY: Retrospective; histopathological and immunohistochemical analysis. SETTING: Referral center, university hospital. SAMPLE: 28 cases of lymphocytic infiltrates of difficult differential diagnosis selected from the records. MAIN MEASUREMENTS: Eighteen histological variables and the immunophenotypic profile were assessed using the CD4, CD8, CD3, CD20 and CD30 lymphoid markers and compared to subsequent follow-up. RESULTS: The most common diagnoses were: initial mycosis fungoides (eight cases) and drug reactions (five cases). Single morphological variables did not discriminate between benign and malignant infiltrates except for the presence of Pautrier-Darier's microabscesses, which were found only in mycosis fungoides (p = 0.015). Patterns of superficial and deep infiltration (p = 0.037) and also the presence of eosinophils (p = 0.0207) were more frequently found in benign lymphocytic infiltrates. Immunohistochemical profile of T-cell subsets showed overlap between benign and malignant infiltrates with a predominance of CD4-positive (helper) lymphocytes in the majority of cases. CONCLUSIONS: A combination of clinical and histological features remains the most reliable approach for establishing a definite diagnosis in cases of lymphoid skin infiltrates.

Limb Length Discrepancy on an 11-Month-Old Boy with Osteoid Osteoma / Discrepância de membros em menino de 11 meses de idade associada a osteoma osteoide

Abstract Osteoid osteoma is a benign bone tumor that frequently occurs between the ages of 10 and 25 years old; in about 80% of the patients, it is associated with intense pain. The present article describes the case of an 11-month-old infant with claudication, right lower limb shortening, and painless right leg volume increase. Image studies demonstrated an osteolytic lesion with small ossifications within, involved by cortical thickening of the right tibial diaphysis. The diagnostic hypotheses were osteoid osteoma, chronic osteomyelitis (Brodie abscess), Ewing sarcoma, and Langerhans cell histiocytosis. Microorganismcultures were negative and the histopathological exam demonstrated osteoid osteoma. The present report expands the knowledge on osteoid osteoma as a cause of painless limping and lower limb shortening in infancy. The early differential diagnosis is important, as surgical excision is curative and prevents further complications.

Resumo Osteoma osteoide é umtumor ósseo benigno,mais frequentedos 10aos 25anos de idadee, em cerca de 80% dos pacientes, está associado a dor forte. O presente artigo descreve um pacientemasculino apresentando claudicação, encurtamento domembro inferior direito e aumento de volume indolor da perna direita desde os 11 meses de idade. Os exames de imagem demonstraram lesão osteolítica contendo pequenas ossificações de permeio, envolvidas por espessamento cortical da diáfise da tíbia direita. As hipóteses diagnósticas de osteoma osteoide, de osteomielite crônica (abscesso de Brodie), de sarcoma de Ewing e de histiocitose de células de Langerhans foram levantadas. As culturas para microrganismos foram negativas e o exame histopatológico demonstrou osteoma osteoide. O presente relato expande o conhecimento sobre osteoma osteoide como causa de claudicação e discrepância demembros inferiores indolor emlactente.Odiagnóstico diferencial precoce é importante, pois a exérese da lesão é curativa e previne sequelas futuras.

Common recessive limb girdle muscular dystrophies differential diagnosis: why and how?

Limb girdle muscular dystrophies are heterogeneous autosomal hereditary neuromuscular disorders. They produce dystrophic changes on muscle biopsy and they are associated with mutations in several genes involved in muscular structure and function. Detailed clinical, laboratorial, imaging, diagnostic flowchart, photographs, tables, and illustrated diagrams are presented for the differential diagnosis of common autosomal recessive limb girdle muscular dystrophy subtypes diagnosed nowadays at one reference center in Brazil. Preoperative image studies guide muscle biopsy site selection. Muscle involvement image pattern differs depending on the limb girdle muscular dystrophy subtype. Muscle involvement is conspicuous at the posterior thigh in calpainopathy and fukutin-related proteinopathy; anterior thigh in sarcoglycanopathy; whole thigh in dysferlinopathy, and telethoninopathy. The precise differential diagnosis of limb girdle muscular dystrophies is important for genetic counseling, prognostic orientation, cardiac and respiratory management. Besides that, it may probably, in the future, provide specific genetic therapies for each subtype.

Muscle phenotypic variability in limb girdle muscular dystrophy 2 G.

Limb girdle muscular dystrophy type 2 G (LGMD2G) is caused by mutations in the telethonin gene. Only few families were described presenting this disease, and they are mainly Brazilians. Here, we identified one additional case carrying the same common c.157C > T mutation in the telethonin gene but with an atypical histopathological muscle pattern. In a female patient with a long duration of symptoms (46 years), muscle biopsy showed, in addition to telethonin deficiency, the presence of nemaline rods, type 1 fiber predominance, nuclear internalization, lobulated fibers, and mitochondrial paracrystalline inclusions. Her first clinical signs were identified at 8 years old, which include tiptoe walking, left lower limb deformity, and frequent falls. Ambulation loss occurred at 41 years old, and now, at 54 years old, she presented pelvic girdle atrophy, winging scapula, foot deformity with incapacity to perform ankle dorsiflexion, and absent tendon reflexes. The presence of nemaline bodies could be a secondary phenomenon, possibly associated with focal Z-line abnormalities of a long-standing disease. However, these new histopathological findings, characteristic of congenital myopathies, expand muscle phenotypic variability of telethoninopathy.

The relative frequency of common neuromuscular diagnoses in a reference center / Frequência relativa de diagnósticos neuromusculares comuns em um serviço de referência

ABSTRACT The diagnostic procedure in neuromuscular patients is complex. Knowledge of the relative frequency of neuromuscular diseases within the investigated population is important to allow the neurologist to perform the most appropriate diagnostic tests. Objective: To report the relative frequency of common neuromuscular diagnoses in a reference center. Methods: A 17-year chart review of patients with suspicion of myopathy. Results: Among 3,412 examinations, 1,603 (46.98%) yielded confirmatory results: 782 (48.78%) underwent molecular studies, and 821 (51.21%) had muscle biopsies. The most frequent diagnoses were: dystrophinopathy 460 (28.70%), mitochondriopathy 330 (20.59%), spinal muscular atrophy 158 (9.86%), limb girdle muscular dystrophy 157 (9.79%), Steinert myotonic dystrophy 138 (8.61%), facioscapulohumeral muscular dystrophy 99 (6.17%), and other diagnoses 261 (16.28%). Conclusion: Using the presently-available diagnostic techniques in this service, a specific limb girdle muscular dystrophy subtype diagnosis was reached in 61% of the patients. A neuromuscular-appropriate diagnosis is important for genetic counseling, rehabilitation orientation, and early treatment of respiratory and cardiac complications.

RESUMO O procedimento diagnóstico neuromuscular é complexo. O conhecimento da frequência relativa das doenças neuromusculares em uma população é importante para utilização dos testes diagnósticos mais apropriados. Objetivo: Relatar a frequência relativa de doenças neuromusculares em um centro de referência. Métodos: Revisão de prontuários de pacientes com suspeita de miopatia em 17 anos. Resultados: Dentre 3412 exames, 1603 (46,98%) foram confirmatórios: 782 (48,78%) estudos moleculares e 821 (51,21%) biópsias musculares. Os diagnósticos mais frequentes foram: distrofinopatia 460 (28,70%), mitocondriopatia 330 (20.59%), atrofia muscular espinhal 158 (9,86%), distrofia muscular cintura-membros 157 (9,79%), distrofia miotônica de Steinert 138 (8,61%), distrofia muscular face-escápulo-umeral 99 (6,17%) e outros diagnósticos 261 (16,28%). Conclusão: Utilizando as técnicas diagnósticas atualmente disponíveis em nosso serviço, o diagnóstico específico do subtipo de distrofia muscular cintura-membros foi obtido em 61% dos pacientes. O diagnóstico neuromuscular apropriado é importante para o aconselhamento genético, orientações de reabilitação e tratamento precoce de complicações respiratórias e cardíacas.