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Acta Myol. 2009 July; 28(1): 40.
PMCID: PMC2859649

O-2. Phenotypic spectrum of laing distal myopathy. Study of an endemic focus in La Safor, Valencia, Spain

Laing distal myopathy have been identified in families and sporadic cases around the world. However, there are still undetermined issues such the spectrum of clinical phenotype, the concurrence of cardiomyopathy and the profile of pathological findings. We report a large cluster of patients, with distal myosinopathy, originating from La Safor region, Spain, due to K1729del mutation in the MYH7 gene. Starting from 7 index cases, 4 unrelated pedigrees were built up. Seventy five individuals were examined and 32 of them were affected; information from additional 27 deceased or not yet examined patients were also recorded. Clinical data, CK levels, EKG, echocardiography, electrophysiologic tests, muscle MRI/TC and muscle biopsies were analyzed. Sequencing of exon 36 of MYH7 gene and haplotype analyses were performed. Age at onset ranged from congenital to 50’s. All patients had anterior compartment muscle weakness and most of them had neck flexor, finger extensor and mild facial weakness. Proximal muscle weakness was found in 60%. The spectrum of disability ranged from asymptomatic to wheelchair confined patients. No signs of neuropathy were found. Cardiomyopathy was only found in 1 patient who had additional cardiovascular factors. MRI showed a high degree of selective involvement of the anterior compartment muscles of the lower legs in all patients, followed by involvement of quadriceps. All affected individuals segregated the mutation. A common haplotype was found in the 4 families. The most consistent pathological finding was the hypotrophy-atrophy of type 1 fibres and an abnormal oxidative enzyme activity. Our series expand the phenotypic spectrum and exclude cardiomyopathy and neuropathy as components of the Laing myopathy with the K1729del mutation.

Articles from Acta Myologica are provided here courtesy of Pacini Editore