EP092: Germline mosaicism in severe BICD2-associated lower extremity-predominant spinal muscular atrophy type 2 with arthrogryposis multiplex congenita

Abstract

Lower extremity-predominant spinal muscular atrophy type 2 (SMALED2) is a progressive muscular atrophy disease caused by heterozygous pathogenic variants in the BICD2 gene. The phenotype of SMALED2 is a spectrum of disease currently subdivided into two subgroups--lower extremity-predominant spinal muscular atrophy type 2A (SMALED2A- MIM# 615290) and 2B (SMALED2B- MIM# 618291). Type 2A is well described with early childhood-onset weakness and atrophy predominantly seen in the lower extremities. Type 2B is more severe, with onset in utero with decreased fetal movement.