Introduction. Patients with CHAPLE syndrome due to loss-of-function biallelic variants in CD55 encoding for the Decay-Accelerating Factor respond effectively to the CD55 complement inhibitor monoclonal antibody Eculizumab. We report the progress in the control of the disease with long-term therapy in a child with CD55 deficiency.
Case Presentation. The patient is three years and seven months-old boy and was born from consanguineous parents. He developed early-onset generalized edematous syndrome with isolated, non-dysenteric diarrhea at 5 months old. Later, he developed severe hypoalbuminemia, leukocytosis, mild anemia and thrombocytosis, hypertriglyceridemia, and hypogammaglobulinemia (low IgG and IgA with normal IgE and IgM). Initially, an Inflammatory Bowel Disease was considered but the response to enteral nutrition with polymeric formula was transient. The family history led to consider a genetic syndrome and WES revealed a novel homozygous biallelic LOF variant in CD55 (c.108_109del; p.Cys36Trpfs*8) confirming CHAPLE syndrome. As shown previously in the literature, long-term therapy with the monoclonal Antibody (mAb) Eculizumab can control most manifestations of the disease. Therefore, the patient was placed on this therapy after prophylactic antibiotics and vaccination. The patient exhibited a rapid response to Eculizumab with resolution of the anemia, hypoalbuminemia, and edemas, with normalization of serum Immunoglobulins (Igs). Since then, he has not required hospitalizations for albumin or Ig infusions and the chronic diarrhea is now under control, for a total of 2 years of mAb therapy. Currently, Eculizumab is infused every 21 days and the patient tolerates oral feeding and has gain weight and size for its age.
Discussion. We report the successful treatment of the first Colombian patient with CD55 deficiency with the mAb Eculizumab, safely and effectively inducing remission of most manifestations in this disease.