Association of plastin 3 expression with disease severity in spinal muscular atrophy only in postpubertal females.

OBJECTIVE To investigate the potential association of plastin 3 (PLS3) expression levels in the blood with disease severity in spinal muscular atrophy (SMA). DESIGN Measurement of PLS3 messenger RNA levels in the blood of patients with types I, II, and III SMA. SETTING Pediatric Neuromuscular Clinical Research Network SMA Natural History study. PARTICIPANTS A cohort of 88 patients of both sexes who had SMA. MAIN OUTCOME MEASURES Levels of PLS3 messenger RNA in relation to SMA type and SMN2 copy number. RESULTS Prepubertal female and younger male (<11 years) patients had approximately 2-fold-higher levels of PLS3 expression than did postpubertal female and older male (≥11 years) patients, respectively (P ≤ .001). Expression of PLS3 in male patients did not correlate with SMA clinical type or SMN2 copy number in either age group (P > .10). In postpubertal female patients, PLS3 expression was greatest in patients with type III SMA, was intermediate in patients with type II SMA, and was lowest in patients with type I SMA. Expression of PLS3 correlated with SMA type, SMN2 copy number, and the gross motor function measure only in postpubertal female patients. CONCLUSION The PLS3 gene may be an age- and/or puberty-specific and sex-specific modifier of SMA.