Distal Myopathy With Posterior Leg And Anterior Hand Involvement

Distal myopathy with posterior leg and anterior hand involvement, also named distal ABD-filaminopathy, is a neuromuscular disease characterized by a progressive symmetric muscle weakness of anterior upper and posterior lower limbs.

Epidemiology

It has been described in several members of an Australian and an Italian family.

Clinical description

The disease usually manifests during the third decade of life with thenar muscle weakness resulting in reduced grip strength. The disease is slowly progressive and generally proceeds with calf muscle weakness appearing during the fourth decade and proximal muscles becoming perceptibly affected in the fifth decade. The tibial anterior muscle is spared, so is respiratory function. Mild cardiomyopathy can sometimes be observed.

Etiology

The disease is due to mutations on the actin-binding domain of the FLNC gene that encodes filamin C, a muscle specific filamin that is also associated with myofibrillar myopathy when mutations affect other parts of the protein. The disease mechanism seems to be linked to an increased actin-binding affinity of filamin C.

Genetic counseling

Transmission is autosomal dominant.