Hyper IgM in tricho-hepato-enteric syndrome due to TTC37 mutation

Abstract

Tricho-hepato-enteric syndrome (THES) (OMIM #222,470) is a rare autosomal recessive syndromic enteropathy whose primary manifestations are dysmorphism, intractable diarrhea, failure to thrive, hair abnormalities, liver disease, and immunodeficiency with low serum IgG concentrations. THES is caused by mutations of either Tetratricopeptide Repeat Domain 37 (TTC37) or Ski2 like RNA Helicase (SKIV2L), genes that encode two components of the human SKI complex. Here, we report a patient with a TTC37 homozygous mutation phenotypically typical for tricho-hepato-enteric syndrome in whom extremely elevated IgM with low IgG was present at the time of diagnosis. These manifestations were not previously described in THES patients and this raised our index of suspicion towards "atypical" hyper IgM syndrome. Although the pathogenesis of immunoglobulin production dysfunction in THES is still elusive, this disorder should be considered in the differential diagnosis in patients with elevated IgM and syndromic features.

Keywords: Class switch recombination; IgM; Immunodeficiency; Tricho-hepato-enteric syndrome.