MedGen

The dystrophinopathies cover a spectrum of X-linked muscle disease ranging from mild to severe that includes Duchenne muscular dystrophy, Becker muscular dystrophy, and DMD-associated dilated cardiomyopathy (DCM). The mild end of the spectrum includes the phenotypes of asymptomatic increase in serum concentration of creatine phosphokinase (CK) and muscle cramps with myoglobinuria. The severe end of the spectrum includes progressive muscle diseases that are classified as Duchenne/Becker muscular dystrophy when skeletal muscle is primarily affected and as DMD-associated DCM when the heart is primarily affected. Duchenne muscular dystrophy (DMD) usually presents in early childhood with delayed motor milestones including delays in walking independently and standing up from a supine position. Proximal weakness causes a waddling gait and difficulty climbing stairs, running, jumping, and standing up from a squatting position. DMD is rapidly progressive, with affected children being wheelchair dependent by age 12 years. Cardiomyopathy occurs in almost all individuals with DMD after age 18 years. Few survive beyond the third decade, with respiratory complications and progressive cardiomyopathy being common causes of death. Becker muscular dystrophy (BMD) is characterized by later-onset skeletal muscle weakness. With improved diagnostic techniques, it has been recognized that the mild end of the spectrum includes men with onset of symptoms after age 30 years who remain ambulatory even into their 60s. Despite the milder skeletal muscle involvement, heart failure from DCM is a common cause of morbidity and the most common cause of death in BMD. Mean age of death is in the mid-40s. DMD-associated DCM is characterized by left ventricular dilation and congestive heart failure. Females heterozygous for a DMD pathogenic variant are at increased risk for DCM. [from GeneReviews]

Pompe disease is classified by age of onset, organ involvement, severity, and rate of progression. Infantile-onset Pompe disease (IOPD; individuals with onset before age 12 months with cardiomyopathy) may be apparent in utero but more typically onset is at the median age of four months with hypotonia, generalized muscle weakness, feeding difficulties, failure to thrive, respiratory distress, and hypertrophic cardiomyopathy. Without treatment by enzyme replacement therapy (ERT), IOPD commonly results in death by age two years from progressive left ventricular outflow obstruction and respiratory insufficiency. Late-onset Pompe disease (LOPD; including: (a) individuals with onset before age 12 months without cardiomyopathy; and (b) all individuals with onset after age 12 months) is characterized by proximal muscle weakness and respiratory insufficiency; clinically significant cardiac involvement is uncommon. [from GeneReviews]

Dysferlinopathy includes a spectrum of muscle disease characterized by two major phenotypes: Miyoshi muscular dystrophy (MMD) and limb-girdle muscular dystrophy type 2B (LGMD2B); and two minor phenotypes: asymptomatic hyperCKemia and distal myopathy with anterior tibial onset (DMAT). MMD (median age of onset 19 years) is characterized by muscle weakness and atrophy, most marked in the distal parts of the legs, especially the gastrocnemius and soleus muscles. Over a period of years, the weakness and atrophy spread to the thighs and gluteal muscles. The forearms may become mildly atrophic with decrease in grip strength; the small muscles of the hands are spared. LGMD2B is characterized by early weakness and atrophy of the pelvic and shoulder girdle muscles in adolescence or young adulthood, with slow progression. Other phenotypes in this spectrum are scapuloperoneal syndrome and congenital muscular dystrophy. Asymptomatic hyperCKemia is characterized by marked elevation of serum CK concentration only. DMAT is characterized by early and predominant distal muscle weakness, particularly of the muscles of the anterior compartment of the legs. [from GeneReviews]

Dysferlinopathy includes a spectrum of muscle disease characterized by two major phenotypes: Miyoshi muscular dystrophy (MMD) and limb-girdle muscular dystrophy type 2B (LGMD2B); and two minor phenotypes: asymptomatic hyperCKemia and distal myopathy with anterior tibial onset (DMAT). MMD (median age of onset 19 years) is characterized by muscle weakness and atrophy, most marked in the distal parts of the legs, especially the gastrocnemius and soleus muscles. Over a period of years, the weakness and atrophy spread to the thighs and gluteal muscles. The forearms may become mildly atrophic with decrease in grip strength; the small muscles of the hands are spared. LGMD2B is characterized by early weakness and atrophy of the pelvic and shoulder girdle muscles in adolescence or young adulthood, with slow progression. Other phenotypes in this spectrum are scapuloperoneal syndrome and congenital muscular dystrophy. Asymptomatic hyperCKemia is characterized by marked elevation of serum CK concentration only. DMAT is characterized by early and predominant distal muscle weakness, particularly of the muscles of the anterior compartment of the legs. [from GeneReviews]

Autosomal dominant myosin storage congenital myopathy-7A (CMYP7A) is a skeletal muscle disorder with wide phenotypic variability. The age at symptom onset can range from early childhood to late adulthood. Affected individuals have proximal muscle weakness affecting the upper and lower limbs and distal muscle weakness of the lower limbs, resulting in gait difficulties and scapular winging (scapuloperoneal myopathy). Additional features may include thin habitus, high-arched palate, foot drop, pes cavus, calf pseudohypertrophy, and decreased reflexes. The severity is also variable: some patients develop respiratory insufficiency, joint contractures, and scoliosis in the first decades, whereas others are clinically unaffected, but show subtle signs of the disorder on examination. Serum creatine kinase may be normal or elevated. The disease is usually slowly progressive and most patients remain ambulatory. Skeletal muscle biopsy can show different abnormalities, including hyaline bodies, type 1 fiber predominance, congenital fiber-type disproportion (CFTD), and nonspecific myopathic changes with myofibrillar disarray. Intrafamilial variability is common (Dye et al., 2006; Pegoraro et al., 2007; review by Tajsharghi and Oldfors, 2013). For a discussion of genetic heterogeneity of congenital myopathy, see CMYP1A (117000). [from OMIM]

Autosomal dominant limb-girdle muscular dystrophy is characterized by proximal and/or distal muscle weakness and atrophy. The age at onset is variable and can range from the first to the sixth decade, although later onset is less common. Most patients present with proximal muscle weakness that progresses to distal involvement, but some can present with distal impairment. The severity is variable: patients with a more severe phenotype can lose ambulation after several decades and have facial weakness with bulbar and respiratory involvement. Muscle biopsy shows dystrophic changes with protein aggregates, myofibrillar degeneration, and rimmed vacuoles (summary by Ruggieri et al., 2015). Genetic Heterogeneity of Autosomal Dominant Limb-Girdle Muscular Dystrophy Other forms of autosomal dominant LGMD include LGMDD2 (608423), previously LGMD1F, caused by mutation in the TNPO3 gene (610032) on chromosome 7q32; LGMDD3 (609115), previously LGMD1G, caused by mutation in the HNRNPDL gene (607137) on chromosome 4q21; and LGMDD4 (618129), previously LGMD1I, caused by mutation in the CAPN3 gene (114240) on chromosome 15q15. For a discussion of autosomal recessive LGMD, see 253600. [from OMIM]

POLG-related disorders comprise a continuum of overlapping phenotypes that were clinically defined long before their molecular basis was known. Most affected individuals have some, but not all, of the features of a given phenotype; nonetheless, the following nomenclature can assist the clinician in diagnosis and management. Onset of the POLG-related disorders ranges from infancy to late adulthood. Alpers-Huttenlocher syndrome (AHS), one of the most severe phenotypes, is characterized by childhood-onset progressive and ultimately severe encephalopathy with intractable epilepsy and hepatic failure. Childhood myocerebrohepatopathy spectrum (MCHS) presents between the first few months of life and about age three years with developmental delay or dementia, lactic acidosis, and a myopathy with failure to thrive. Other findings can include liver failure, renal tubular acidosis, pancreatitis, cyclic vomiting, and hearing loss. Myoclonic epilepsy myopathy sensory ataxia (MEMSA) now describes the spectrum of disorders with epilepsy, myopathy, and ataxia without ophthalmoplegia. MEMSA now includes the disorders previously described as spinocerebellar ataxia with epilepsy (SCAE). The ataxia neuropathy spectrum (ANS) includes the phenotypes previously referred to as mitochondrial recessive ataxia syndrome (MIRAS) and sensory ataxia neuropathy dysarthria and ophthalmoplegia (SANDO). About 90% of persons in the ANS have ataxia and neuropathy as core features. Approximately two thirds develop seizures and almost one half develop ophthalmoplegia; clinical myopathy is rare. Autosomal recessive progressive external ophthalmoplegia (arPEO) is characterized by progressive weakness of the extraocular eye muscles resulting in ptosis and ophthalmoparesis (or paresis of the extraocular muscles) without associated systemic involvement; however, caution is advised because many individuals with apparently isolated arPEO at the onset develop other manifestations of POLG-related disorders over years or decades. Of note, in the ANS spectrum the neuropathy commonly precedes the onset of PEO by years to decades. Autosomal dominant progressive external ophthalmoplegia (adPEO) typically includes a generalized myopathy and often variable degrees of sensorineural hearing loss, axonal neuropathy, ataxia, depression, parkinsonism, hypogonadism, and cataracts (in what has been called "chronic progressive external ophthalmoplegia plus," or "CPEO+"). [from GeneReviews]

POLG-related disorders comprise a continuum of overlapping phenotypes that were clinically defined long before their molecular basis was known. Most affected individuals have some, but not all, of the features of a given phenotype; nonetheless, the following nomenclature can assist the clinician in diagnosis and management. Onset of the POLG-related disorders ranges from infancy to late adulthood. Alpers-Huttenlocher syndrome (AHS), one of the most severe phenotypes, is characterized by childhood-onset progressive and ultimately severe encephalopathy with intractable epilepsy and hepatic failure. Childhood myocerebrohepatopathy spectrum (MCHS) presents between the first few months of life and about age three years with developmental delay or dementia, lactic acidosis, and a myopathy with failure to thrive. Other findings can include liver failure, renal tubular acidosis, pancreatitis, cyclic vomiting, and hearing loss. Myoclonic epilepsy myopathy sensory ataxia (MEMSA) now describes the spectrum of disorders with epilepsy, myopathy, and ataxia without ophthalmoplegia. MEMSA now includes the disorders previously described as spinocerebellar ataxia with epilepsy (SCAE). The ataxia neuropathy spectrum (ANS) includes the phenotypes previously referred to as mitochondrial recessive ataxia syndrome (MIRAS) and sensory ataxia neuropathy dysarthria and ophthalmoplegia (SANDO). About 90% of persons in the ANS have ataxia and neuropathy as core features. Approximately two thirds develop seizures and almost one half develop ophthalmoplegia; clinical myopathy is rare. Autosomal recessive progressive external ophthalmoplegia (arPEO) is characterized by progressive weakness of the extraocular eye muscles resulting in ptosis and ophthalmoparesis (or paresis of the extraocular muscles) without associated systemic involvement; however, caution is advised because many individuals with apparently isolated arPEO at the onset develop other manifestations of POLG-related disorders over years or decades. Of note, in the ANS spectrum the neuropathy commonly precedes the onset of PEO by years to decades. Autosomal dominant progressive external ophthalmoplegia (adPEO) typically includes a generalized myopathy and often variable degrees of sensorineural hearing loss, axonal neuropathy, ataxia, depression, parkinsonism, hypogonadism, and cataracts (in what has been called "chronic progressive external ophthalmoplegia plus," or "CPEO+"). [from GeneReviews]

Inclusion body myopathy associated with Paget disease of bone (PDB) and/or frontotemporal dementia (IBMPFD) is characterized by adult-onset proximal and distal muscle weakness (clinically resembling a limb-girdle muscular dystrophy syndrome), early-onset PDB, and premature frontotemporal dementia (FTD). Muscle weakness progresses to involve other limb and respiratory muscles. PDB involves focal areas of increased bone turnover that typically lead to spine and/or hip pain and localized enlargement and deformity of the long bones; pathologic fractures occur on occasion. Early stages of FTD are characterized by dysnomia, dyscalculia, comprehension deficits, and paraphasic errors, with minimal impairment of episodic memory; later stages are characterized by inability to speak, auditory comprehension deficits for even one-step commands, alexia, and agraphia. Mean age at diagnosis for muscle disease and PDB is 42 years; for FTD, 56 years. Dilated cardiomyopathy, amyotrophic lateral sclerosis, and Parkinson disease are now known to be part of the spectrum of findings associated with IBMPFD. [from GeneReviews]

A form of limb-girdle muscular dystrophy that usually has a childhood onset (but can range from the first to third decade of life) of severe progressive proximal weakness, eventually involving the distal muscles. Some patients may remain ambulatory but most are wheelchair dependant 20 years after onset. Caused by homozygous mutation in the titin gene (TTN). [from SNOMEDCT_US]

MDDGB5 is an autosomal recessive congenital muscular dystrophy with impaired intellectual development and structural brain abnormalities (Brockington et al., 2001). It is part of a group of similar disorders resulting from defective glycosylation of alpha-dystroglycan (DAG1; 128239), collectively known as 'dystroglycanopathies' (Mercuri et al., 2006). For a discussion of genetic heterogeneity of congenital muscular dystrophy-dystroglycanopathy type B, see MDDGB1 (613155). [from OMIM]

MDGDC5 is an autosomal recessive muscular dystrophy characterized by variable age at onset, normal cognition, and no structural brain changes (Brockington et al., 2001). It is part of a group of similar disorders resulting from defective glycosylation of alpha-dystroglycan (DAG1; 128239), collectively known as 'dystroglycanopathies' (Mercuri et al., 2006). For a discussion of genetic heterogeneity of muscular dystrophy-dystroglycanopathy type C, see MDDGC1 (609308). [from OMIM]

Other signs and symptoms of myofibrillar myopathy can include a weakened heart muscle (cardiomyopathy), muscle pain (myalgia), loss of sensation and weakness in the limbs (peripheral neuropathy), and respiratory failure. Individuals with this condition may have skeletal problems including joint stiffness (contractures) and abnormal side-to-side curvature of the spine (scoliosis). Rarely, people with this condition develop clouding of the lens of the eyes (cataracts).

The signs and symptoms of myofibrillar myopathy vary widely among affected individuals, typically depending on the condition's genetic cause. Most people with this disorder begin to develop muscle weakness (myopathy) in mid-adulthood. However, features of this condition can appear anytime between infancy and late adulthood. Muscle weakness most often begins in the hands and feet (distal muscles), but some people first experience weakness in the muscles near the center of the body (proximal muscles). Other affected individuals develop muscle weakness throughout their body. Facial muscle weakness can cause swallowing and speech difficulties. Muscle weakness worsens over time.

Myofibrillar myopathy is part of a group of disorders called muscular dystrophies that affect muscle function and cause weakness. Myofibrillar myopathy primarily affects skeletal muscles, which are muscles that the body uses for movement. In some cases, the heart (cardiac) muscle is also affected. [from MedlinePlus Genetics]

In WDR62 primary microcephaly (WDR62-MCPH), microcephaly (occipitofrontal circumference [OFC] = -2 SD) is usually present at birth, but in some instances becomes evident later in the first year of life. Growth is otherwise normal. Except for brain malformations in most affected individuals, no other congenital malformations are observed. Central nervous system involvement can include delayed motor development, mild-to-severe intellectual disability (ID), behavior problems, epilepsy, spasticity, and ataxia. [from GeneReviews]

A mild form of limb-girdle muscular dystrophy with characteristics of muscle weakness in the four limbs, mild scapular winging, severe atrophy of the quadriceps and anterior tibialis muscles, calf hypertrophy and lack of respiratory and cardiac involvement. [from SNOMEDCT_US]

The spectrum of ANO5 muscle disease is a continuum that ranges from asymptomatic hyperCKemia and exercise-induced myalgia to proximal and/or distal muscle weakness. The most typical presentation is limb-girdle muscular dystrophy type 2L (LGMD2L) with late-onset proximal lower-limb weakness in the fourth or fifth decade (range 15-70 years). Less common is Miyoshi-like disease (Miyoshi muscular dystrophy 3) with early-adult-onset calf distal myopathy (around age 20 years). Incidental hyperCKemia may be present even earlier. Initial symptoms are walking difficulties, reduced sports performance, and difficulties in standing on toes as well as nonspecific exercise myalgia and/or burning sensation in the calf muscles. Muscle weakness and atrophy are frequently asymmetric. Cardiac findings can include cardiomyopathy and arrhythmias and/or left ventricular dysfunction. Bulbar or respiratory symptoms have not been reported. Females have milder disease manifestations than males. Disease progression is slow in both the LGMD and distal forms; ambulation is preserved until very late in the disease course. Life span is normal. [from GeneReviews]

MDDGC9 is an autosomal recessive muscular dystrophy showing onset in early childhood. It is part of a group of similar disorders resulting from defective glycosylation of DAG1, collectively known as 'dystroglycanopathies' (summary by Hara et al., 2011). For a discussion of genetic heterogeneity of muscular dystrophy-dystroglycanopathy type C, see MDDGC1 (609308). [from OMIM]

Salih myopathy is characterized by muscle weakness (manifest during the neonatal period or in early infancy) and delayed motor development; children acquire independent walking between ages 20 months and four years. In the first decade of life, global motor performance is stable or tends to improve. Moderate joint and neck contractures and spinal rigidity may manifest in the first decade but become more obvious in the second decade. Scoliosis develops after age 11 years. Cardiac dysfunction manifests between ages five and 16 years, progresses rapidly, and leads to death between ages eight and 20 years, usually from heart rhythm disturbances. [from GeneReviews]

Autosomal recessive limb-girdle muscular dystrophy-17 (LGMDR17) is characterized by early childhood onset of proximal muscle weakness and atrophy without skin involvement. One family has shown rapid progression of the disorder in adolescence (summary by Gundesli et al., 2010). For a discussion of genetic heterogeneity of autosomal recessive limb-girdle muscular dystrophy, see LGMDR1 (253600). [from OMIM]

Autosomal recessive limb-girdle muscular dystrophy-6 (LGMDR6) is a very rare and severe neuromuscular disorder with onset in most patients in the first decade of life. Generalized muscle weakness affecting predominantly proximal and distal muscles of the limbs is progressive, and patients require walking aids or become wheelchair-bound. Some patients have cardiomyopathy or heart rhythm abnormalities, or require ventilatory support (Alonso-Perez et al., 2022). For a discussion of genetic heterogeneity of autosomal recessive limb-girdle muscular dystrophy, see LGMDR1 (253600). [from OMIM]