Abstract
Arginase deficiency (ARG1-D) is an autosomal recessive inborn error of metabolism that is often misdiagnosed. Classic presentation of ARG1-D includes progressive symptoms of spasticity, delayed development, cognitive impairment, protein avoidance, and seizures. Patients who present atypically may evade diagnosis and require a thoughtful diagnostic workup. Here, we discuss three females of Latin American origin with differing clinical presentations, but who all have the same intronic pathogenic variant in ARG1. Importantly, we found that each case included elevated coagulopathy on laboratory testing and discussed one case in particular with manifestation of bleeding. When diagnosed early, treatment is favorable and can prevent progressive decline. While many states have added ARG1-D to their expanded newborn screening panels, still many states and countries do not screen for ARG1-D, and it can be missed in a healthy newborn. We aim to bring awareness to not only the classic presentation as a necessary consideration for otherwise unexplained spastic diplegia but also to the varied presentations of ARG1-D.