Calf Hypertrophy Research Articles

G.P.82 ‘Double Trouble’: Diagnostic challenges in DMD in patients with an additional hereditary skeletal dysplasia

Duchenne muscular dystrophy (DMD) is an X-linked disease that is caused by mutations in the dystrophin gene and affects one in 3600–6000 live male births. DMD is characterized by progressive weakness leading to a loss of ambulation, respiratory insufficiency, cardiomyopathy and scoliosis. Boys typically present at 3–5years of age with evidence of proximal weakness and calf hypertrophy. Here we describe the unusual and complicated clinical phenotype of three patients with hereditary skeletal dysplasias in whom an additional diagnosis of DMD was then established. Two unrelated boys presented each with a diagnosis of osteogenesis imperfecta (types 1 and 4) due to point mutations in COL1A1, and were both subsequently found to have a 1bp frameshift deletion in the dystrophin gene at age 3 and age 15, respectively. The third patient had an established diagnosis of inherited pseudoachondroplasia and was found to have a deletion of exons 48–50 in dystrophin at age 8years. We discuss the atypical clinical presentation caused by the concomitant presence of two conditions affecting the musculoskeletal system, emphasizing features that may confound the presentation of a well-characterized disease like DMD. Additional case series of patients with DMD and a secondary genetically confirmed condition are necessary to establish the natural history in this “double trouble” patient population. The recognition and accurate diagnosis of patients with two independent genetic disease processes is essential for management, prognosis, proper genetic recurrence risk information, and discussion regarding potential therapeutic interventions.

G.P.41 The identification of LGMD2G (TCAP) in Australia

The limb-girdle MDs (LGMDs) are characterised by predominant weakness and wasting of pelvic and shoulder girdle muscles with onset after two years of age. Recessive mutations in the TCAP gene (encoding telethonin), were first identified as the cause of LGMD2G in 2000. Only a handful of families have been reported to date. Here, we report the ninth family with LGMD2G. The proband (P1) is a 32year old male with an affected sister, five unaffected siblings and first-cousin parents of Chinese-Cambodian descent. P1 had slowly progressive muscle weakness since his late teenage years. On examination at 27years of age, he had bilateral Achilles contractures, mild calf hypertrophy, asymmetric scapular winging and normal facial strength except mild weakness of eye closure. There was moderate weakness of hip movements and knee extension and mild weakness of most other muscle groups, except hand and wrist movements. We performed genome-wide linkage analysis assuming autosomal recessive inheritance using Illumina 660WQ SNP platform and found positive LOD scores for the chromosomal region 17p11.2-q22, containing the TCAP gene, as well as regions on chromosomes 7, 16 and 18. Sanger sequencing of TCAP revealed a homozygous 8 base pair duplication (c.26_33dupAGGTGTCG) resulting in a frameshift and truncated protein (p.R12fsX31), predicted to abolish telethonin expression. Two other families of Chinese origin have been reported with the same homozygous mutation. A muscle MRI at 28years of age demonstrated widespread asymmetric fatty infiltration of lower limb muscles in a pattern similar to that reported in another LGMD2G patient by CT imaging. In conclusion, LGMD2G is rare, but exists outside Brazil and our identification of a third Asian LGMD2G family with the p.R12fsX31 mutation suggests this may be a population-specific mutation. Consistency in the pattern of muscle involvement on MRI or CT in two LGMD2G patients suggests this investigation may be a useful tool for diagnosis.

G.O.6 Autosomal recessive desminopathy with desmin-null mutations presenting in childhood

Abstract Desminopathies are intermediate filament disorders with a mainly dominant autosomal inheritance pattern, characterized by skeletal myopathy and/or cardiomyopathy with average onset in the 3rd decade. The clinical phenotype caused by desmin mutations is described as a myofibrillar myopathy (MFM). This term refers to a group of genetically heterogeneous neuromuscular disorders that share histopathological features of cytoplasmic aggregates of multiple proteins, including desmin, αB-crystallin and myotilin on muscle biopsy. We report on two siblings from healthy, non-consanguineous parents presenting with progressive generalized proximal more than distal muscle weakness in legs and arms from the age of 3 years, facial weakness and ptosis, reduced upward gaze, scapular winging, ankle contractures, mild calf hypertrophy, and swallowing difficulties. No cardiac involvement was detected so far. Creatine kinase levels were raised up to 800 and 1000 IU/L. A muscle MRI of the thigh showed more severe involvement of the posterior compartment with relative sparing of the sartorius and gracilis muscles. Muscle histopathology showed myopathic features with atrophic fibers, nuclear bags, internal nuclei and type 1 fibre predominance with remarkably complete absence of desmin labelling which was confirmed by Western blot. Mutation analysis revealed two compound heterozygous mutations in exon 1 of desmin gene resulting in premature stop codons. This novel clinical phenotype linked to autosomal recessive desminopathy widens the clinical spectrum of this class of disease.

Hereditary myopathy with early respiratory failure associated with a mutation in A-band titin

Hereditary myopathy with early respiratory failure and extensive myofibrillar lesions has been described in sporadic and familial cases and linked to various chromosomal regions. The mutated gene is unknown in most cases. We studied eight individuals, from three apparently unrelated families, with clinical and pathological features of hereditary myopathy with early respiratory failure. The investigations included clinical examination, muscle histopathology and genetic analysis by whole exome sequencing and single nucleotide polymorphism arrays. All patients had adult onset muscle weakness in the pelvic girdle, neck flexors, respiratory and trunk muscles, and the majority had prominent calf hypertrophy. Examination of pulmonary function showed decreased vital capacity. No signs of cardiac muscle involvement were found. Muscle histopathological features included marked muscle fibre size variation, fibre splitting, numerous internal nuclei and fatty infiltration. Frequent groups of fibres showed eosinophilic inclusions and deposits. At the ultrastructural level, there were extensive myofibrillar lesions with marked Z-disc alterations. Whole exome sequencing in four individuals from one family revealed a missense mutation, g.274375T>C; p.Cys30071Arg, in the titin gene (TTN). The mutation, which changes a highly conserved residue in the myosin binding A-band titin, was demonstrated to segregate with the disease in all three families. High density single nucleotide polymorphism arrays covering the entire genome demonstrated sharing of a 6.99 Mb haplotype, located in chromosome region 2q31 including TTN, indicating common ancestry. Our results demonstrate a novel and the first disease-causing mutation in A-band titin associated with hereditary myopathy with early respiratory failure. The typical histopathological features with prominent myofibrillar lesions and inclusions in muscle and respiratory failure early in the clinical course should be incentives for analysis of TTN mutations.

Eight new mutations and the expanding phenotype variability in muscular dystrophy caused by ANO5

Description of 8 new ANO5 mutations and significant expansion of the clinical phenotype spectrum associated with previously known and unknown mutations to improve diagnostic accuracy. DNA samples of 101 patients in 95 kindreds at our quaternary referral center in Finland, who had undetermined limb-girdle muscular dystrophy (LGMD), calf distal myopathy, or creatine kinase (CK) elevations of more than 2,000 IU/L, were selected for ANO5 genetic evaluation, and the clinical findings of patients with mutations were retrospectively analyzed. A total of 25 patients with muscular dystrophy caused by 11 different recessive mutations in the ANO5 gene were identified. The vast majority of mutations, 8 of 11, proved to be previously unknown new mutations. The most frequent mutation, c.2272C>T (p.R758C), was present in 20 patients. The phenotypes associated with this and the common European mutation, c.191dupA, varied from nearly asymptomatic high hyperCKemia to severe LGMD with consistently milder phenotypes in female patients. Mutations in ANO5 are a frequent cause of undetermined muscular dystrophy, with both distal and proximal presentation. Other types include high hyperCKemia, myalgia, or calf hypertrophy over decades without significant weakness, especially in female patients. Mutations are distributed all over the gene, indicating that muscular dystrophy caused by ANO5 can be expected to occur in all populations.

Pathological mechanism of lumbar disc herniation resulting in neurogenic muscle hypertrophy

We present a 33-year-old man with 5-year history of low back pain who presented with an enlarging right calf. The patient underwent an extensive workup including biopsy without diagnosis. The patient’s examination was significant for diminished pinprick sensation in the right L5/S1 dermatome. Reflexes were absent in the right ankle. The circumference of the right calf (58 cm) was twice that of the left. MRI revealed a herniated lumbar disc at the L5/S1 level. He then underwent a L5/S1 microdiscectomy. Following this surgery, the patient noted complete resolution of all sensory deficits in his lower extremity. His calf circumference had decreased by 5 cm at 4 months and by a total of 8 cm at his 2-year post-operative visit. Histological examination of the affected muscle demonstrated severe grouped atrophy of both type I and type II fibers. There was also evidence of compensatory fiber hypertrophy as well as fiber splitting. We concluded that the patient suffered from a herniated lumbar disc causing radiculopathy with calf hypertrophy (neurogenic hypertrophy). To our knowledge this is the first report of both grouped atrophy and compensatory hypertrophy of both muscle fiber types seen in this phenomenon.

Thousands of Lesions in Disseminated Cysticercosis

Human cysticercosis is an important cause of seizures in the developing world. A small subset of patients acquires heavy infections with large numbers of lesions disseminated throughout the brain and skeletal muscle.1 Manifestations of heavy multiple cysticercotic syndromes include cysticercal encephalitis or signs and symptoms related to location. A 30-year-old man presented with intermittent partial complex seizures and headache for the previous 2 years. Examination revealed widespread small pea-sized nodules throughout the body, including the tongue (Figure 1). Calf hypertrophy was present (Figure 2). Higher mental function, cranial nerves, and motor, sensory, and reflexes were normal. An enzyme-linked immunsorbent assay for Taenia solium antibody was positive at high titers. A T2 sagittal magnetic resonance image of the brain showed numerous circumscribed lesions with visible scolices and involving adjacent soft tissues (Figure 3). Cysticercosis is caused by the cestode larvae of the pork tapeworm T. solium. Disseminated cysticercosis has the potential to cause severe clinical manifestations.2 Figure 1. Tongue of the patient demonstrating larval cyst. Figure 2. Photograph of the patient revealing calf hypertrophy. Figure 3. Magnetic resonance imaging of the cranium, T2 weighted sagittal image showing multiple well-circumscribed cysts with presence of scolex.

P2.32 Rare association of recessive limb-girdle muscular dystrophies in a Portuguese family

Limb-girdle muscular dystrophies (LGMDs) are rare hereditary muscle diseases. The recessive form is the most common with the dominant form accounting for 10% of all cases of LGMD. We present a family with two members in two successive generations afflicted with distinct recessive LGMDs. Caucasian female, 33 years old, born of a non consanguineous couple, complaining of weakness in the lower limbs since 7 years of age. The weakness was progressive and at 9 years of age she lost the ability to walk and noticed difficulty in raising the arms. On neurological examination the patient was alert, without signs of cognitive deterioration. There was macroglossia, calf hypertrophy, shortened Achilles tendons and elbow and knee contractures. Voluntary movements were observed only in finger extension G2 and plantar flexion G2. Neck flexion was also weak, G2. The deep tendon reflexes were abolished. Ophthalmological examination revealed bilateral subcapsular cataract and pigmented retinopathy. The CK value was slightly elevated. A pathogenic mutation on the β -sarcoglycan gene was identified. Caucasian female, 62 years old, born of a first degree consanguineous couple, mother of clinical case 1. Complaints of weakness in the lower limbs began ten years ago. Neurological examination revealed upper and lower limb proximal weakness, G4, distal lower limbs myotactic arreflexia, Gower’s sign and lumbar hyperlordosis. Ophthalmological examination was normal. CK value was elevated. A pathogenic mutation on the dysferlin gene was identified. The presence of hereditary muscle disease in two persons of the same family should raise the suspicion of an autosomal dominant transmission. This casual rare association of different recessive LGMDs can be explained by the high rate of consanguinity in some areas of Portugal. Muscle immunohistochemistry was essential for a correct diagnosis of LGMD.

Charcot-marie-tooth disease with intermediate conduction velocities caused by a novel mutation in the MPZ gene

Charcot-Marie-Tooth (CMT) disease is a heterogeneous group of inherited sensory and motor neuropathies. Mutations in the gene that encodes for myelin protein zero (MPZ) can produce different phenotypes: CMT1 (with low conduction velocities), CMT2 (less frequent and with unaffected conduction velocities), and CMTID (with intermediate conduction velocities). We report a study of seven patients from a four-generation family. All the affected members of the family had a typical CMT phenotype, but three of them had calf hypertrophy. The nerve conduction velocities (NCV) in all of them were between 35 and 43 m/s. Molecular study revealed the novel mutation Lys214Met in the MPZ gene. Molecular study of the MPZ gene would be useful in cases of CMT in families with intermediate NCV, especially if no mutations in the GJB-1 gene are found or there is male-to-male transmission.

Functional muscle analysis of the Tcap knockout mouse

Autosomal recessive limb‐girdle muscular dystrophy type 2G (LGMD2G) is an adult‐onset myopathy characterized by distal lower limb weakness, calf hypertrophy, and progressive decline in ambulation. The disease is caused by mutations in Tcap, a z‐disc protein of skeletal muscle, although the precise mechanisms resulting in clinical symptoms are unknown. To provide a model for preclinical trials and for mechanistic studies, we generated knockout mice carrying a null mutation in the TCAP gene. Here we present the first report of a Tcap knockout mouse model for LGMD2G and the results of an investigation into the effects of Tcap deficiency on skeletal muscle function in 4‐month‐ and 12‐month‐old mice. Muscle histology of Tcap‐null mice revealed abnormal myofiber size variation with central nucleation, similar to findings in the muscles of LGMD2G patients. An analysis of a Tcap binding protein, myostatin, showed that deletion of TCAP was accompanied by increased protein levels of myostatin. Our Tcap‐null mice exhibited a decline in the ability to maintain balance on a rotating rod, relative to wild‐type controls. No differences were detected in force or fatigue assays of isolated extensor digitorum longus (EDL) and soleus muscles. Finally, a mechanical investigation of EDL and soleus indicated an increase in muscle stiffness in knockout animals. We are the first to establish a viable knockout mouse model of Tcap deficiency and our model mice demonstrate a dystrophic phenotype comparable to humans with LGMD2G.Support: M.K. Childers Laboratory Startup Fund

Functional muscle analysis of the Tcap knockout mouse

Autosomal recessive limb-girdle muscular dystrophy type 2G (LGMD2G) is an adult-onset myopathy characterized by distal lower limb weakness, calf hypertrophy and progressive decline in ambulation. The disease is caused by mutations in Tcap, a z-disc protein of skeletal muscle, although the precise mechanisms resulting in clinical symptoms are unknown. To provide a model for preclinical trials and for mechanistic studies, we generated knockout (KO) mice carrying a null mutation in the Tcap gene. Here we present the first report of a Tcap KO mouse model for LGMD2G and the results of an investigation into the effects of Tcap deficiency on skeletal muscle function in 4- and 12-month-old mice. Muscle histology of Tcap-null mice revealed abnormal myofiber size variation with central nucleation, similar to findings in the muscles of LGMD2G patients. An analysis of a Tcap binding protein, myostatin, showed that deletion of Tcap was accompanied by increased protein levels of myostatin. Our Tcap-null mice exhibited a decline in the ability to maintain balance on a rotating rod, relative to wild-type controls. No differences were detected in force or fatigue assays of isolated extensor digitorum longus (EDL) and soleus (SOL) muscles. Finally, a mechanical investigation of EDL and SOL indicated an increase in muscle stiffness in KO animals. We are the first to establish a viable KO mouse model of Tcap deficiency and our model mice demonstrate a dystrophic phenotype comparable to humans with LGMD2G.

A new locus on 3p23–p25 for an autosomal-dominant limb-girdle muscular dystrophy, LGMD1H

Limb-girdle muscular dystrophies (LGMDs) are a genetically heterogeneous group of neuromuscular disorders with a selective or predominant involvement of shoulder and pelvic girdles. We clinically examined 19 members in a four-generation Italian family with autosomal-dominant LGMD. A total of 11 subjects were affected. Clinical findings showed variable expressivity in terms of age at onset and disease severity. Five subjects presented with a slowly progressive proximal muscle weakness, in both upper and lower limbs, with onset during the fourth-fifth decade of life, which fulfilled the consensus diagnostic criteria for LGMD. Earlier onset of the disease was observed in a group of patients presenting with muscle weakness and/or calf hypertrophy, and/or occasionally high CK and lactate serum levels. Two muscle biopsies showed morphological findings compatible with MD associated with subsarcolemmal accumulation of mitochondria and the presence of multiple mitochondrial DNA deletions. A genome-wide scan performed using microsatellite markers mapped the disease on chromosome 3p23-p25.1 locus in a 25-cM region between markers D3S1263 and D3S3685. The highest two-point LOD score was 3.26 (theta=0) at marker D3S1286 and D3S3613, whereas non-parametric analysis reached a P-value=0.0004. Four candidate genes within the refined region were analysed but did not reveal any mutations. Our findings further expand the clinical and genetic heterogeneity of LGMDs.

Sarcoglycanopathy: Clinical and histochemical characteristics in 66 patients

Sarcoglycanopathies are a group or autosomal recessive muscular dystrophies designated as α, β, γ, or δ sarcogycanopathy. It is a retrospective analysis of case series. Sixty six patients immunohistochemically confirmed to have sarcoglycan deficiency were included in the analysis. The study period extended from 1997-2008. The male to female ratio was 1.5:1. Mean age at the onset of muscle complaints was 6.2±3.7 years (range 1-18). Mean age at evaluation was 10.0±4.8 years (range 3-31). Mean duration of illness was 47.02±44.80 months (range 3-325). Onset in the first decade was seen in 59 (89.4%) and 25 (42.4%) of these had onset before five years of age. The remaining seven (10.6%) had onset in second decade and none after 20 years of age. Consanguinity was present in 54 (81.8%). In 34 of 66 cases only a-SG was carried out and this had shown total absence of staining in all fibers. In the remaining 32 cases where the entire panel was performed, absence of all sarcoglycans was noted in 10 (15.1%), isolated α-SG deficiency in 7 (10.6%), isolated β-SG deficiency in 6 (9.1%), and isolated γ-SG deficiency in 3 (4.5%). Combination deficiency was also observed: absence of α and β (n=4), β and γ (n=2), and α and γ (n=1). Our series was a large series and with predominantly pediatric age group. Sarcoglycanopathy should be particularly suspected in a child born to consanguineous parents and who presents with proximal muscle weakness and calf hypertrophy, elevated CK level, and myopathic pattern on EMG.

Whole-body high-field MRI shows no skeletal muscle degeneration in young patients with recessive myotonia congenita

Muscle magnetic resonance imaging (MRI) is the most sensitive method in the detection of dystrophic and non-dystrophic abnormalities within striated muscles. We hypothesized that in severe myotonia congenita type Becker muscle stiffness, prolonged transient weakness and muscle hypertrophy might finally result in morphologic skeletal muscle alterations reflected by MRI signal changes. To assess dystrophic and/or non-dystrophic alterations such as fatty or connective tissue replacement and muscle edema in patients with severe recessive myotonia congenita. We studied three seriously affected patients with myotonia congenita type Becker using multisequence whole-body high-field MRI. All patients had molecular genetic testing of the muscle chloride channel gene (CLCN1). Molecular genetic analyses demonstrated recessive CLCN1 mutations in all patients. Two related patients were compound heterozygous for two novel CLCN1 mutations, Q160H and L657P. None of the patients showed skeletal muscle signal changes indicative of fatty muscle degeneration or edema. Two patients showed muscle bulk hypertrophy of thighs and calves in line with the clinical appearance. We conclude that (i) chloride channel dysfunction alone does not result in skeletal muscle morphologic changes even in advanced stages of myotonia congenita, and (ii) MRI skeletal muscle alterations in myotonic dystrophy must be clear consequences of the dystrophic disease process.

Correction of Asymmetric Calf Hypertrophy with Differential Selective Neurectomy

Contour asymmetry of the legs is a major aesthetic concern among Asian women. This study enrolled 60 patients with asymmetric calf hypertrophy, defined as a differential calf circumference exceeding 0.6 cm. Differential selective neurectomy techniques, which depend on the sizes of the small and large calves, were performed exactly via a 1-cm popliteal wound. The pre- and postoperative mean differences between the larger and smaller calf circumferences at the 1-year follow-up consultation were 1.38 +/- 0.65 and 0.42 +/- 0.38 cm, respectively (p < 0.01). The reduction was significantly greater in the leg that was initially larger. The procedure was effective in reducing circumference discrepancies so that leg contours were more balanced. All the patients were able to ambulate normally within 5 months after the procedure without disability. The authors posit that differential neurectomy is a safe and reliable technique for the correction of asymmetric calf hypertrophy, with minimal morbidities.

G.P.7.08 A new form of myopathy in four siblings with a distinctive muscle MRI pattern

We present a non-consanguineous family in which four children (two males and two females) have an early-onset myopathy with a distinctive pattern of muscle involvement both clinically and on muscle MRI. The children had congenital hypotonia, myopathic faces, walked between ages 16 and 20 months with waddling gaits and developed scapular winging, thigh atrophy and calf hypertrophy, mild elbow contractures and a stiff neck/upper back. Joint laxity was only observed in the thumbs. Intelligence is normal.

Neurogenic muscle hypertrophy

We report the case of a 48-year-old man who presented with left calf hypertrophy 6 years after an episode of left S1 sciatica related to a herniated disk. Magnetic resonance imaging disclosed muscle hypertrophy. Electromyography showed left S1 radiculopathy with abnormal spontaneous muscle activity. Neurogenic muscle hypertrophy is a rare phenomenon that is chiefly seen when denervation occurs slowly and gradually. The typical patient is a middle-aged man who has a history of S1 radiculopathy. The soleus muscle is the main site of involvement. The pathophysiology is unclear but may involve type I fiber hypertrophy in response to the complex repetitive discharges recorded by electromyography. The natural history of neurogenic muscle hypertrophy is incompletely understood.

Eosinophilic myositis as presenting symptom in γ-sarcoglycanopathy

The patient reported here presented with first symptoms at the age of 10 showing an abnormal gait, calf hypertrophy and winged scapulae. She was diagnosed with eosinophilic myositis after muscle biopsy. A second muscle biopsy at the age of 20 and subsequent genetic testing, however, revealed the underlying condition of a primary γ-sarcoglycanopathy, or LGMD2C. To our knowledge, this is the first LGMD2C patient reported who initially presented with eosinophilic myositis. Eosinophilia has been reported previously in patients with Calpainopathy and Becker Muscular Dystrophy and might be an early, but transient feature of a wider range of muscular dystrophies.

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.

G.P.13.11 Autosomal centronuclear myopathy in a Turkish family

Centronuclear myopathies are clinically and genetically heterogenous diseases with the characteristic morphology of centrally located nuclei in the vast majority of muscle fibers. We describe three cases from one family. A 59-yr-old woman presented with slowly progressive weakness of both legs and arms which had developed at the age of 40. The neurological examination revealed symmetrical diffuse weakness with proximal predominance. Muscle weakness was more pronounced in the lower extremities (especially in the posterior group-thigh extensors and knee flexors) with calf hypertrophy.