A 27-year-old Australian-born woman named Mrs. B presented to her general practitioner in December 2010 with a three-month history of excessive tiredness. She has a supportive husband, and they have four children aged four months to five years old. Mrs. B was breastfeeding her youngest child and had initially attributed her fatigue to her busy home life. A blood test revealed an elevated white blood cell count (WBC) of 43.7 x 109/L (reference range: 4–11 x 109/L); hemoglobin and platelets were within normal range. Mrs. B was subsequently referred to a specialist hematology service.