Third trimester hydrops fetalis as the presentation leads to prenatal diagnosis of familial hemophagocytic lymphohistiocytosis

OBJECTIVE: We first report a case of familial hemophagocytic lymphohistiocytosis (FHL) diagnosed in utero due to third trimester hydrops fetalis. CASE REPORT: /L). Exome sequencing (ES) detected a novel homozygous pathogenic frameshift variant c.65del, p(Pro22ArgfsTer29) in PRF1 with biparental inheritance. Biallelic pathogenic variants in PRF1 are associated with FHL. CONCLUSION: This case indicates that third trimester hydrops fetalis with fetal anemia and thrombocytopenia are the diagnostic clue to the FHL. The use of prenatal ES can achieve a definite diagnosis.