[P3-108] Peripheral nerve pathology of spinal muscular atrophy with respiratory distress type1 (SMARD1)
Spinal muscular atrophy with respiratory distress type1 (SMARD1) is characterized by severe respiratory failure due to diaphragmatic paralysis and distal muscular weakness within early infancy. After an initial decline of the respiratory state and motor function until the 1-2 years, residual capabilities reaches a plateau. Although peripheral neuropathology of SMARD1 at the onset in early infancy has been reported as an axonal neuropathy, its temporal change over clinical course is still unclear.
We report the peripheral neuropathological findings of a SMARD1 patient at 1 year and 1 month old. His clinical course was severe compared with past reports of SMARD1, and his respiratory and motor function had reached a plateau before he was 1 year old. Genetic screening identified compound heterozygous novel mutation in IGHMBP2 gene ([c.826C>T, p.Q276X] + [c.1702C>T, p.Q568X]). Peripheral nerve tissue obtained by sural nerve biopsy showed the reduction of myelinated fibers, increased interstitial spaces with collagen tissue, scattered unmyelinated nerve fibers and increased Schwann cells around unmyelinated fibers forming pseudo-onion bulb structure, which indicated end-stage of progressed axonal degeneration. These findings suggest the rapid progression of peripheral axonal neuropathy in SMARD1 that leads its characteristic clinical course of respiratory failure and paralysis in early infantile period.
We report the peripheral neuropathological findings of a SMARD1 patient at 1 year and 1 month old. His clinical course was severe compared with past reports of SMARD1, and his respiratory and motor function had reached a plateau before he was 1 year old. Genetic screening identified compound heterozygous novel mutation in IGHMBP2 gene ([c.826C>T, p.Q276X] + [c.1702C>T, p.Q568X]). Peripheral nerve tissue obtained by sural nerve biopsy showed the reduction of myelinated fibers, increased interstitial spaces with collagen tissue, scattered unmyelinated nerve fibers and increased Schwann cells around unmyelinated fibers forming pseudo-onion bulb structure, which indicated end-stage of progressed axonal degeneration. These findings suggest the rapid progression of peripheral axonal neuropathy in SMARD1 that leads its characteristic clinical course of respiratory failure and paralysis in early infantile period.