BackgroundPeople with group O blood are considered universal organ donors compatible with any other blood group. However, in the case of minor ABO‐incompatible transplantation, immune‐mediated hemolysis may occur due to concomitant transfer of donor B lymphocytes together with the allograft. These passenger lymphocytes can produce antibodies in the recipients erythrocytes, causing hemolytic anemia known as passenger lymphocyte syndrome (PLS).MethodsA retrospective chart review was performed.ResultsA 6‐year‐old boy (A+) underwent transplantation of a kidney from his father (O+). On postoperative day (POD) 6, the patient developed fever with no explainable causes. On POD 11, he presented with abdominal pain, hematochezia, and severe diarrhea, with sudden hemolytic anemia. Since then, GI symptoms have continued. On POD 20, direct antiglobulin test (DAT) was positive, and the anti‐A IgM/G titer was 2/32. The results of the anti‐A antibody elution test were strongly positive (3+). These findings highly suggested PLS. On the same day, the GI symptoms suddenly worsened, and laboratory findings showed hemolysis and thrombocytopenia with disseminated intravascular coagulation (DIC). Abdominal computed tomography (CT) scans suggested ischemic colitis of venous origin, and the patient underwent segmental colectomy with ileostomy formation on POD 23. To remove the anti‐A antibodies, the patient underwent therapeutic plasma exchange (TPE) five times until the DAT and anti‐A elution test were negative.ConclusionsWe report a case of gastrointestinal involvement of PLS that occurred after minor ABO‐incompatible kidney transplantation. This is the first report of ischemic colitis as an atypical manifestation of PLS.

Lethal neonatal rigidity and multifocal seizure syndrome (RMFSL) is a severe autosomal recessive epileptic encephalopathy characterized by rigidity, intractable multifocal seizures, microcephaly, apnea, and bradycardia immediately after birth. RMFSL is related to a mutation in breast cancer 1-associated ataxia telangiectasia mutated activation-1 protein (<i>BRAT1</i>). We report a case of a female infant born to non-consanguineous Korean parents who developed hypertonia, dysmorphic features, progressive encephalopathy with refractory seizures at birth, and worsening intermittent apnea, leading to intubation and death at 137 days of age. The initial repeated electroencephalographic findings were normal; however, a pattern of focal seizures emerged at 35 days of life. Rapid trio whole-exome sequencing revealed heterozygous mutations c.1313_1314delAG p.(Gln438Argfs*51) and c.1276C>T p. (Gln426*) in <i>BRAT1</i>. After genetic counseling for pregnancy planning, a preimplantation genetic diagnosis for targeted <i>BRAT1</i> mutations was successfully performed, and a healthy baby was born. To our knowledge, this is the first reported case of a Korean patient with compound heterozygous mutations in <i>BRAT1</i>. An early and accurate genetic diagnosis can help provide timely treatment to patients and indicate the need for reproductive counseling for parents for family planning.