Novel Presentation of Major Histocompatibility Complex Class II Deficiency with Hemophagocytic Lymphohistiocytosis

PURPOSE

Major histocompatibility complex (MHC) class II deficiency is one of the combined immune deficiency disorders caused by defects in the MHC class II regulatory genes leading to abnormal T cells development and function. Therefore, patients mainly present with increased susceptibility to infections, diarrhea, and failure to thrive. In this report, we present one MHC class II deficient patient with a novel presentation with Hemophagocytic Lymphohistiocytosis (HLH).

METHODS

Immunophenotyping of lymphocyte subpopulations and HLA-DR expression was assess by flow cytometry. Gene mutational analysis was performed by whole exome and Sanger sequencing.

RESULTS

We reported a 7-year-old girl, who was diagnosed at age of 2 years with MHC class II deficiency by genetic testing and flow cytometry. Two years later, she developed disseminated BCGitis which was treated with proper antimicrobial agents. At the age of 7 years, she presented with clinical features fulfilling 6 diagnostic criteria of HLH including evidence of hemophagocytic activity in bone marrow aspiration. Accordingly, the diagnosis of HLH was established and the patient was started on IV Dexamethasone, Anakinra and IVIG. Eventually, patient started to improve and was discharged in good condition. Few months later, the patient was readmitted with severe pneumonia and sepsis leading to death.

CONCLUSION

Patients with MHC class II deficiency might present with disseminated BCGitis especially if the patient has severe T cell lymphopenia. Additionally, this immune defect might be added to the list of inborn errors of immunity that can be complicated with HLH.

Clinical, Immunological, and Genetic Findings in Iranian Patients with MHC-II Deficiency: Confirmation of c.162delG RFXANK Founder Mutation in the Iranian Population

PURPOSE

Major histocompatibility complex class II (MHC-II) deficiency is a rare inborn error of immunity (IEI). Impaired antigen presentation to CD4 + T cells results in combined immunodeficiency (CID). Patients typically present with severe respiratory and gastrointestinal tract infections at early ages. Hematopoietic stem cell transplantation (HSCT) is the only curative therapy.

METHODS

We describe the clinical, immunologic, and genetic features of eighteen unrelated Iranian patients with MHC-II deficiency.

RESULTS

Consanguinity was present in all affected families. The median age at the initial presentation was 5.5 months (range 7 days to 18 years). The main symptoms included failure to thrive, persistent diarrhea, and pneumonia. Autoimmune and neurologic features were also documented in about one-third of the patients, respectively. Thirteen patients carried RFXANK gene mutations, two carried RFX5 gene mutations, and three carried a RFXAP gene mutation. Six patients shared the same RFXANK founder mutation (c.162delG); limited to the Iranian population and dated to approximately 1296 years ago. Four of the patients underwent HSCT; three of them are alive. On the other hand, nine of the fourteen patients who did not undergo HSCT had a poor prognosis and died.

CONCLUSION

MHC-II deficiency is not rare in Iran, with a high rate of consanguinity. It should be considered in the differential diagnosis of CID at any age. With the limited access to HSCT and its variable results in MHC-II deficiency, implementing genetic counseling and family planning for the affected families are mandatory. We are better determined to study the c.162delG RFXANK heterozygous mutation frequency in the Iranian population.