SNP Shot: Genomic Insights

Myopathy with iron-sulfur cluster assembly enzyme deficiency is a genetic condition mainly affecting the muscles responsible for body movement (skeletal muscles). It generally spares other muscle types, like the heart (cardiac muscle).

Beginning in early childhood, individuals with this condition experience significant fatigue after physical activity (exercise intolerance). Even light activity leads to rapid heartbeat (tachycardia), breathlessness, and muscle weakness and pain. However, muscle strength is typically normal when at rest.

Extended or repeated physical exertion can lead to more serious problems, including rhabdomyolysis, the breakdown of muscle tissue. This process releases myoglobin, a protein, into the bloodstream. The kidneys process and excrete myoglobin in the urine (myoglobinuria), causing it to appear red or brown. Myoglobin can also injure the kidneys, potentially causing life-threatening kidney failure in some cases.

For most individuals affected by this condition, the muscle-related issues do not worsen over time. However, at least two individuals with a severe form of this disorder have experienced worsening muscle weakness and muscle loss starting in childhood.

Inheritance:

The inheritance pattern of this condition is autosomal recessive. This means that both copies of the responsible gene in each cell must have mutations for the condition to manifest. Each parent of an individual with an autosomal recessive condition carries one copy of the mutated gene but usually doesn't exhibit symptoms of the condition.