Unexpected Non-Maternally Derived Anti-PP1Pk in an 11-Week-Old Patient.

Alloantibody formation at less than 4 months of age is rare. Most antibodies identified in these patients are maternally derived. Anti-PP1Pk was detected in an 11-week-old infant that was not maternally derived. A multidisciplinary team approach led to appropriate testing, diagnosis, and transfusion management in this critically ill infant.