FLVCR1 and Posterior column ataxia - retinitis pigmentosa: However, disruptions in heme homeostasis—due to mutations in heme transporters such as FLVCR1 or impaired heme–regulatory protein interactions—can result in neurodegenerative diseases, including Posterior Column Ataxia and Retinitis Pigmentosa (PCARP), Alzheimer’s disease, and Parkinson’s disease.