Monothiol glutaredoxin involved in the biogenesis of iron-sulfur clusters. Required for normal iron homeostasis. Required for normal regulation of hemoglobin synthesis by the iron-sulfur protein ACO1. Defects in GLRX5 are a cause of anemia sideroblastic pyridoxine-refractory autosomal recessive (PRARSA). A form of sideroblastic anemia not responsive to pyridoxine. Sideroblastic anemia is characterized by anemia of varying severity, hypochromic peripheral erythrocytes, systemic iron overload secondary to chronic ineffective erythropoiesis, and the presence of bone marrow ringed sideroblasts. Sideroblasts are characterized by iron-loaded mitochondria clustered around the nucleus. Belongs to the glutaredoxin family. Monothiol subfamily. Note: This description may include information from UniProtKB.