A 45-year-old man who works in a battery manufacturing plant presents with fatigue, abdominal pain, and difficulty gripping objects. He reports constipation and memory problems over the past few months. On examination, he has pallor, a bluish discoloration along the gumline (Burton’s lines), and weakness in wrist extension (wrist drop). Laboratory tests show microcytic anemia with basophilic stippling of red blood cells.Which of the following mechanisms explains the development of anemia in this patient?
