CYB5R3(Cytochrome b5 reductase 3) also known as DIA1 consists of 301 amino acids and is encoded by the human gene CYB5R3. CYB5R3 plays a crucial role in the desaturation and elongation of fatty acids, cholesterol biosynthesis, and drug metabolism, making CYB5R3 essential for maintaining cellular lipid homeostasis and detoxifying harmful substances. Additionally, in erythrocytes, CYB5R3 is vital for the reduction of methemoglobin, which is important for ensuring efficient oxygen transport in the blood. Notably, a serine residue at position 117 of CYB5R3 is predominantly found in individuals of African descent, highlighting the potential for genetic variation in enzyme function and its implications for health.