P 328. Novel Homozygous Variants Confirm SPTBN4-Related Congenital Myopathy and Expand the Clinical Phenotype

Background: Congenital myopathies are a group of rare Mendelian disorders characterized by hypotonia, hyporeflexia, and generalized weakness with clinical onset in early life. The molecular basis is heterogeneous, with disease-causing genes implicated in different cellular functions. Recently, one patient was reported with a homozygous variant in the SPTBN4 gene, encoding for βIV-spectrin, a nonerythrocytic member of the β-spectrin family. Here, we report two more families with three patients harboring novel homozygous variants of SPTBN4.