N.P.2 02 Wide clinical spectrum among SMA patients carrying 2 or 3 SMN2 copies: limitation of SMN2 copy numbers as clinical prognostic indicator in individual cases

Abstract

SMN2, a nearly identical copy gene of SMN, produces small amounts of SMN RNA/protein. SMN2 copy number has been correlated with clinical severity in SMA patients and the use of copy number has been advocated as clinical prognostic indicator to make informed decisions on management and therapy. We analysed phenotype–genotype correlation in SMA patients with 2 or 3 SMN2 copies. Review of medical files of 31 patients, mean age 11.9 yrs (14–27 months) with confirmed homozygous absence of SMN1 and analysis of SMN2 copies by quantitative PCR.