Pena-Shokeir phenotype is a rare disorder. However, its etiology is incompletely understood. It may be familial or may be due to anoxic-ischemic etiology. Although rare, it can affect one twin in a monoamniotic pregnancy, most likely due to early cord entanglement.
Keywords: Fetal akinesia deformation sequence; Pena–Shokeir syndrome; fetal cord entanglement; monoamniotic twins.