An Unusual Cause of Non-5Q Spinal Muscular Atrophy: DYNCH1-related Disease

Case presentation: This is a five-year-old boy, admitted with global development delay associated with limb deformities. He was born prematurely at 35 weeks, by cesarean delivery due to pelvic presentation. During pregnancy, the mother noticed reduced fetal movements, and at birth, neonatal resuscitation with hospitalization was required. He was born with congenital arthrogryposis (CA), with thumbs in bilateral adduction, restricted plantar movement, global hypotonia, and facial dysmorphisms. Later, behavioral and cognitive changes became evident, leading to the diagnosis of autism spectrum disorder. Laboratorial work-up revealed mild CPK elevation. Genetic testing identified a heterozygous DYNCH1 pathogenic variant (p.Arg1201Ser), confirming the diagnosis of Spinal Muscular Atrophy Lower Extremity - predominant (SMALED – OMIM: 158600).