SNP Shot: Genomic Insights

Miyoshi myopathy is a muscular disease characterized by initial weakness in the distal muscles, particularly those in the legs. Typically, individuals in their early to mid-adult years start noticing muscle weakness and wasting (atrophy) in their calf muscles, affecting either one or both legs. When only one leg is affected, the calves will appear uneven in size (asymmetrical). Weakness in the calf muscles can hinder the ability to stand on one's toes.

As Miyoshi myopathy progresses gradually, the muscle weakness and atrophy extend upwards from the legs to include the thigh and buttock muscles. The muscles of the upper arm and shoulder can also become involved. Over time, those affected may find it challenging to climb stairs or walk long distances. In some cases, individuals with Miyoshi myopathy may ultimately require the use of a wheelchair.

In rare instances, individuals with Miyoshi myopathy have developed irregular heartbeats (arrhythmias). A hallmark of Miyoshi myopathy is significantly elevated levels of creatine kinase (CK) in the blood, an enzyme that serves as an indicator of muscle disease.

Inheritance:

This disorder follows an autosomal recessive inheritance pattern. This means that both copies of the relevant gene in each cell must contain mutations for the condition to manifest. Each parent of someone with an autosomal recessive condition carries one copy of the mutated gene; however, they usually do not exhibit any symptoms of the condition themselves.