The reference OMIM entry for this protein is 160500

Myopathy, distal, 1; mpd1
Myopathy, late distal hereditary
Laing distal myopathy
Myopathy, distal, early-onset, autosomal dominant

A number sign (#) is used with this entry because distal myopathy-1 (MPD1), also known as Laing distal myopathy, is caused by heterozygous mutation in the MYH7 gene (160760), which encodes the myosin heavy chain of type 1 fibers of skeletal muscle and cardiac ventricles, on chromosome 14q11. The MYH7 gene is mutated in both hypertrophic (see 192600) and dilated (see 115200) cardiomyopathy as well as in myosin storage myopathy (608358).

CLINICAL FEATURES

Laing et al. (1995) described a family with an autosomal dominant distal myopathy closely resembling that described in the original report of Gowers (1902). Scoppetta et al. (1995) and Voit et al. (2001) reported 2 families with autosomal dominant distal myopathy with clinical features similar to those reported by Laing et al. (1995). Characteristics common to both families included onset in the second or third year of life, selective wasting and weakness of the anterior tibial and extensor digitorum longus muscles, a slowly progressive course, and, at later stages, involvement of hand extensors, neck flexor, and abdominal muscles. Some patients developed tremor. Zimprich et al. (2000) described an Austrian family with a similar phenotype. In a family with 9 affected members spanning 3 generations, Mastaglia et al. (2002) described selective weakness of the ankle dorsiflexors and toe extensors, in particular the extensor hallucis longus. Ankle plantar flexors were normal, even in the most advanced cases. There was also weakness and atrophy of the anterior compartment muscles. Most cases had selective weakness of the long finger extensor muscles. None of the affected individuals had cardiomyopathy. Age at onset varied from 4 to 5 years to the early twenties. Muscle MRI showed atrophy of affected muscles, EMG gave a myopathic pattern, and muscle biopsy of 2 affected patients showed myopathic changes without rimmed vacuoles. Hedera et al. (2003) reported a large Italian American kindred in which at least 11 members spanning 3 generations were affected with an autosomal dominant distal myopathy. Clinical features included weakness of foot and toe extensor muscles, and some patients had proximal weakness. No patient had distal weakness of the upper extremities or neck muscles, even in advanced stages of the disease. The average age at symptom onset was 20 years. Two affected patients had signs of idiopathic dilated cardiomyopathy. Hedera et al. (2003) noted that their family differed from the family reported by Laing et al. (1995) by the absence of upper extremity weakness and neck muscle weakness. Darin et al. (2007) reported a Tanzanian boy with distal myopathy and mild dilated cardiomyopathy. He began walking on the toes at age 11 months and had Achilles tenotomy at age 6 years. Examination at age 7 showed weakness of the great toe and ankle dorsiflexors, atrophy of the anterior tibial muscles, weakness of the hip flexors, and decreased reflexes. Echocardiography showed mild left atrial enlargement and prolonged isovolumetric relaxation time. Skeletal muscle biopsy showed hypotrophy of type 1 fibers and apparent absence of type 2B fibers. Serum creatine kinase was mildly elevated. - Clinical Variability Muelas et al. (2010) identified the same mutation in the MYH7 gene (lys1729del; 160760.0044) in 29 clearly affected individuals from 4 unrelated families in the Safor region of Spain. There was great phenotypic variability. The age at onset ranged from congenital to 50 years, wit ... More on the omim web site

Subscribe to this protein entry history

Feb. 10, 2018: Protein entry updated
Automatic update: Entry updated from uniprot information.

Feb. 2, 2018: Protein entry updated
Automatic update: Uniprot description updated

Dec. 19, 2017: Protein entry updated
Automatic update: Uniprot description updated

Nov. 23, 2017: Protein entry updated
Automatic update: Uniprot description updated

March 25, 2017: Additional information
No protein expression data in P. Mayeux work for MYH7

March 16, 2016: Protein entry updated
Automatic update: OMIM entry 160500 was added.