This research study is focused on patients who have Cystathionine beta synthase deficiency Homocystinuria (CBSDH). The purpose of this study is to test the safety and tolerability of an investigational drug called OT-58 (the study drug). An "investigational drug" is a drug that is being tested and is not approved by the U.S. Food and Drug Administration (FDA). Specifically, this study will measure how much OT-58 gets into the blood stream, how long it takes the body to get rid of it, and whether it reduces the amount of homocysteine in your blood.

This study will evaluate the safety and tolerability of RGX-111 in patients with Mucopolysaccharidosis Type I with a neurocognitive deficit that are at least 4 months old. This study involves administration of the RGX-111, general anesthesia, lumbar puncture, blood draws, MRI, ultrasound, electrocardiogram, echocardiogram, hearing test, and chart review.