Chapter 33 - Distal Myopathies

Abstract

More than 20 genetically separated distal myopathies have been characterized. Most of them are adult or late onset, although a few distal myopathies have infantile, childhood, or juvenile onset, and the myopathic forms of distal arthrogryposis are in fact congenital distal myopathies. Involvement of proximal muscles is usually rather late and loss of ambulation infrequent, except in Miyoshi myopathy. Comprehensive diagnostic efforts to reach a final genetic diagnosis are important because confusion with neurogenic conditions is very common. Worldwide the most frequent early onset form is the autosomal dominant Laing distal myopathy. In addition, distal nebulin myopathy, autosomal recessive form of oculopharyngeal distal myopathy, KLHL9-mutated distal myopathy, distal anoctaminopathy, and Miyoshi myopathy are covered including clinical phenotype, muscle imaging, muscle pathology, diagnostic procedures, molecular genetics, molecular pathomechanisms, and therapeutic options.