Bare lymphocyte syndrome is a rare form of combined immunodeficiency characterized by complete or partial lack of major histocompatability complex (MHC) expression. Defects in MHC class II result in early onset bacterial, viral, fungal, and protozoal infections. Here we describe a patient with MHCII deficiency born in California with normal newborn screening results.
Chromosomal microarray analysis was performed by the UCLA Clinical Microarray Core.
The patient was admitted at 9 months of age with intractable diarrhea, FTT, thrush, and candidal diaper rash. At admission, he had profound hypogammaglobulinemia: IgG <8mg/dL, IgA <7mg/dL, and IgM <5mg/dL. Total T and B lymphocyte counts were conserved with a relative deficiency of the CD4+ subset (CD3 2634, CD4 525, CD8 1887, CD19 1881, CD16/56 331) and inverted CD4/8 ratio of 0.28. Stool was positive for Norovirus, and respiratory studies were positive for Coxsackie/Echovirus. Flow cytometry showed no HLA-DR expression on monocytes and lymphocytes consistent with MHCII deficiency. Allogenic stem cell transplant (SCT) was performed at 11 months of age. Despite initial clinical improvement, norovirus-positive diarrhea and coxsackie/echovirus respiratory infection persisted. He died 91 days post SCT of progressive intestinal and pulmonary complications.
Although not traditionally classified as a form of SCID, MHCII deficiency follows a similar clinical course and arguably should be included in the classification. We here present the first evidence that TREC numbers in MHCII deficiency, although below the mean values for immunocompetent neonates, are well above the current cutoff that is considered abnormal.
Journal of Allergy and Clinical Immunology, Vol. 131, Issue 2, AB71
- AAAAI 2013 (69th)