J Korean Child Neurol Soc.  2006 Nov;14(2):316-321.

Mitochondrial Respiratory Complex I Deficiency Simulating Spinal Muscular Atrophy

• Lee JS
• Ahn MS
• Ryu KH
• Hwang JS
• Jung JW
• Kim SH

Abstract

Two female patients with clinical features resembling spinal muscular atrophy are introduced. Patient 1 presented with hypotonia and proximal weakness of extremities at the age of 4 months. The electromyography revealed motor neuronopathy suggestive of spinal muscular atrophy. Patient 2 presented with severe hypotonia, motor weakness, and joint contractures since birth. The muscle biopsy finding was consistent with spinal muscular atrophy. However, deletions in the survival motor neuron genes and the neuronal apoptosis inhibitor protein genes were not found in both the patients. They finally showed the clinical features against spinal muscular atrophy; epileptic seizures, cardiomyopathy, and spasticity. We measured the mitochondrial respiratory chain complex enzyme activities in cultured skin fibroblasts, whose results were suggestive of isolated complex I deficiency in both the patients. In conclusion, for the patients who have clinical features resembling SMA without any deletions in the SMA genes it should be considered a possibility of the mitochondrial respiratory chain complex I deficiency.

Keyword

Mitochondrial respiratory chain complex deficiency; Spinal muscular atrophy

MeSH Terms

Apoptosis
Biopsy
Cardiomyopathies
Contracture
Electromyography
Electron Transport
Electron Transport Complex I*
Epilepsy
Extremities
Female
Fibroblasts
Humans
Joints
Motor Neurons
Muscle Hypotonia
Muscle Spasticity
Muscular Atrophy, Spinal*
Neurons
Parturition
Skin
Electron Transport Complex I