Fetal akinesia (FA) is a multifaceted disease entity, sharing contractures of multiple joints as a common feature. Although progress has been made in defining the environmental and genetic factors involved, in many affected individuals the causes remain unknown. This study identifies bi-allelic pathogenic DNA variants in the kinesin family member 21A gene (KIF21A) as a new cause of a severe form of neurogenic FA likely due to impaired axonal growth and guidance. These data support improved diagnosis and genetic counseling of FA families. (By Dr. med. Tobias Haack, https://jmg.bmj.com/content/early/2021/11/05/jmedgenet-2021-108064 )