Finnish upper limb-onset distal myopathy

Finnish upper limb-onset distal myopathy is a rare genetic condition that primarily affects the muscles of the hands and arms. It is characterized by slowly progressive weakening and wasting of muscles, starting with the intrinsic muscles of the hand (especially the thenar and hypothenar muscles) and later involving other muscles such as those in the forearm, triceps, and lower extremities. People with this condition may first notice difficulties with hand coordination and clumsiness, which gradually lead to issues such as stumbling and altered gait patterns. As the disease progresses, additional muscle groups are affected asymmetrically, and muscle contractures may develop, contributing to further functional challenges.

Common symptoms include early hand muscle weakness and atrophy, leading to clumsiness, and later difficulties with balance as evidenced by stumbling, especially in the fourth to fifth decades of life. Other signs include a steppage gait and the development of contractures in the hands, with the involvement of both the distal and gradually the proximal muscles.

This condition is genetic in origin. It is caused by mutations that affect muscle function, and a known gene involved is HNRNPA1. The genetic nature of Finnish upper limb-onset distal myopathy means that it is inherited and primarily affects muscle tissue over time.

Information about treatment is currently limited for this condition.

The condition is described as slowly progressive, meaning that muscle weakness and atrophy worsen over time. While affected individuals may experience increasing challenges with daily activities due to muscle degeneration, the pattern and rate of progression can vary between people.

Information about research is currently limited for this condition.