Two Case Reports of Spinal Muscular Atrophy(SMA) Confirmed by Molecular Genetic Studies / 대한임상병리학회지

ABSTRACT

We present two cases of the patients with spinal muscular atrophy(SMA) confirmed by molecular genetic studies. The first one is 1-year-old female child with SMA type II(Dubowitz disease) who visited pediatric outpatient for developmental delay. She presented lower extremity hypotonia which progress to upper extremities and inability to sit alone. Spinal cord MRI showed normal findings but the needle electromyography suggested the possibility of myopathy. Following muscle biopsy findings were consistent with spinal muscular atrophy and PCR-SSCP(polymerase chain reaction-single strand conformation polymorphism) analysis showed homozygous deletion of telomeric SMN(survivor motor neuron) exon 7. The second is a 19-year-old female with SMA type III(Kugelberg-Welander disease) who visited neurologic outpatient for limbs weakness. She presented slowly progressive gait disturbance without muscle atrophy. The significantly decreased motor power of proximal limbs was observed. And findings of electromyography and muscle biopsy were consistent with spinal muscular atrophy. PCR-SSCP analysis revealed homozyous deletion of exon 7 of telomeric SMN and deletion of exon 8 of centromeric SMN gene. PCR analysis for NAIP(neuronal apoptosis inhibitory protein) exon 5 and 13 revealed no deletion in both cases. Molecular genetic analysis for SMN gene will be very useful for rapid diagnosis of spinal muscular atrophy.