Reversal of IgM deficiency following a gluten-free diet in seronegative celiac disease

Selective Ig M deficiency(s IGMD)is very rare;it may be associated with celiac disease(CD).We present the case of an 18-year-old man with s IGMD masking seronegative CD.Symptoms included abdominal pain,diarrhea and weight loss.Laboratory tests showed reduced Ig M,DQ2-HLA and negative anti-transglutaminase.Villous atrophy and diffuse immature lymphocytes were observed at histology.Tissue transglutaminase m RNA mucosal levels showed a 6-fold increase.The patient was treated with a gluten-free diet(GFD)and six months later the symptoms had disappeared,the villous architecture was restored and mucosal tissue transglutaminase m RNA was comparable to that of healthy subjects.After 1 year of GFD,a complete restoration of normal Ig M values was observed and duodenal biopsy showed a reduction of immature lymphocytes and normal appearance of mature immune cells.