EARLY DETECTION OF X-LINKED MOESIN-ASSOCIATED IMMUNE DEFICIENCY ON NEWBORN SCREENING

Abstract

<h3>Introduction</h3> X-Linked Moesin-Associated Immune Deficiency (X-MAID) is a combined T and B cell immunodeficiency that can lead to recurrent bacterial infections, increased susceptibility to varicella zoster virus, and decreased immune response to vaccine antigens. Due to variability of X-MAID severity, cases have been diagnosed in adulthood as well as through state newborn screening. <h3>Case Description</h3> Our patient presented at 7 days old with positive newborn screen for SCID. Laboratory work-up revealed T and B cell lymphopenia with an absolute lymphocyte cell count of 200 and absolute neutrophil count (ANC) of 700. Patient was started on prophylactic Bactrim, acyclovir, and fluconazole and primary immunodeficiency genetic panel was performed. On repeat labs, T cells counts remained low with new monocytopenia. Antimicrobials were held due to concern for bone marrow suppression. Diagnosis of X-MAID was made at 2 months of age when genetic testing returned with a report of pathogenic variant in moesin. Our patient has been doing well on prophylactic antimicrobials, IVIG, and G-CSF without infectious complications at 4 months of age and has been referred for stem cell transplant evaluation. <h3>Discussion</h3> Given the paucity of reported cases of X-MAID and long-term outcomes, management remains ambiguous. With variability in reported cases, the choice between stem cell transplantation versus supportive care with immunoglobulin replacement, antimicrobial prophylaxis, and G-CSF leads to many unanswered questions about best practice. We put forth this case to continue to add to the body of literature and seek to gain more knowledge surrounding the care of these patients.