Early onset chromosome 14-linked distal myopathy (Laing).

A dominantly inherited form of distal myopathy with onset in early childhood was first reported in a 4-generation Australian family in 1995. In the present report we provide further information on the clinical phenotype and natural history of this myopathy, and on the electromyogram and magnetic resonance imaging findings in affected individuals. The pattern of muscle involvement was similar to that in the 'tibial' forms of distal myopathy such as the Finnish (Udd) and Markesbery-Griggs types, with additional involvement of the finger extensors and of some more proximal limb and neck muscles. However, the age of onset was earlier than in these other myopathies and rimmed vacuoles were not found in biopsies from two affected individuals. Evidence of possible anticipation was found in one branch of the family. The gene locus for this myopathy had been mapped to 14q11.2-q13. The linkage region has been refined to a 24 cM region between D14S283 and D14S49 and mutations have been excluded in the PABP2 gene for oculopharyngeal muscular dystrophy which lies within this region.