Complex <i>SMN</i> Hybrids Detected in a Cohort of 31 Patients With Spinal Muscular Atrophy
Mar Costa‐Roger, Laura Campello Blasco, Lorène Gerin, Marta Codina‐Solà, Jordi Leno-Colorado, Marta Gómez‐García de la Banda, Rocio García-Uzquiano, Pascale Saugier-Véber, Séverine Drunat, Susana Quijano‐Roy, Eduardo F. Tizzano
Abstract
Spinal muscular atrophy (SMA) is a recessive neuromuscular disorder caused by the loss or presence of point pathogenic variants in the SMN1 gene. The main positive modifier of the SMA phenotype is the number of copies of the SMN2 gene, a paralog of SMN1, which only produces around 10%–15% of functional SMN protein. The SMN2 copy number is inversely correlated with phenotype severity; however, discrepancies between the SMA type and the SMN2 copy number have been reported. The presence of SMN2-SMN1 hybrids has been proposed as a possible modifier of SMA disease.