Pediatric follow-up and treatment of a patient diagnosed with hereditary CD59 deficiency: A case presentation

CD59 is a regulatory protein specifically required for the preservation of human neuronal tissue. It is encoded as autosomal recessive. It is expressed in a large number of different tissues, including hematopoietic cells, endothelial cells, neurons, and neuroglia. Endothelial damage regulates the complement system by preventing the formation of the C5b-9 complex, which triggers cytotoxicity and neurodegeneration, and thus the membrane attack complex (MAC). Hereditary CD59 deficiency is a rare disease that occurs in childhood with recurrent hemolytic attacks and neurological symptoms (such as ataxia, stroke, epileptic seizures, speech disorder, loss of motor skills). The only known treatment for the disease, for now, is Eculizumab, a monoclonal antibody that acts by inhibiting the formation of MAC via the C5 complement. Therefore, it is very important that a patient diagnosed with CD59 deficiency receive appropriate doses and timely treatment of Eculizumab in order to avoid relieving serious neurological symptoms and to maintain daily life. This study, it was aimed to clarify the follow-up clinical features of a patient diagnosed with hereditary CD59 deficiency and what needs to be considered in the treatment process.