Transmission of chromosomally integrated human herpesvirsus 6 (HHV‐6) variant A from a parent to children leading to misdiagnosis of active HHV‐6 infection

Abstract: Only a handful of cases of chromosomally integrated human herpesvirus 6 (CI‐HHV‐6) have been reported, suggesting that this phenomenon is rare. We here present a familial case of HHV‐6 variant A (HHV‐6A) transmission through a generation, which was identified in the setting of allogeneic hematopoietic stem cell transplantation (HSCT). A 31‐year‐old man with myelodysplastic syndrome underwent allogeneic HSCT from a human leukocyte antigen‐identical sibling, and was found to be continuously yielding high copy numbers of HHV‐6A DNA in plasma evaluated by real‐time polymerase chain reaction (PCR). Antiviral therapy with ganciclovir or foscarnet failed to decrease the copy numbers. HHV‐6A DNA was detected in the patient's buccal mucosa and hair follicles, and was also detected in the plasma, whole blood, and buccal mucosa of the patient's father and 2 siblings, but not in his mother. The sequences of HHV‐6A DNA isolated from all family members were identical. Since monitoring of HHV‐6 by PCR has been widely introduced to the field of HSCT, transplant physicians should be aware of such an alternative form of HHV‐6 transmission, particularly when HHV‐6A is detected.