Objective: Ataxia telangiectasia (A-T) is a rare, disorder caused by mutation in the ATM gene. Neurodegeneration, immunodeficiency and predisposition to malignancies are its main complications. Elevated IgM levels were reported in some A-T patients. As high IgM levels may suggest of a unique immunopathologic involvement, we aimed to characterize the phenotype of A-T patients with high IgM.
Methods: A retrospective review of 46 patient charts followed from 1986 to 2015 at the National A-T Center. Demographic, clinical, and laboratory data were collected and compared between A-T patients with elevated and normal IgM levels.
Results: 15/46(32.6%) patients had higher than normal IgM levels (average 356±200mg/dl) that were significantly higher compared to A-T patients with IgM levels within the accepted norm (average 129.2±56.5 mg/dl, p<0.00001). Colonization of lower respiratory tract with Mycobacterium gordonae and Pseudomonas aeruginosa as well as viral skin infections were more frequent in the high IgM group. Significantly lower KREK-CJ and TREK levels were observed in the high IgM group suggesting a deeper cellular immunodeficiency in this group. Interestingly, lymphoproliferative and solid tumors were significantly more prevalent in patients with normal IgM.
Conclusions: We suggest that the group of A-T patients with high levels of IgM should be considered as a separate sub-group with a unique phenotype. These patients have a discrete immunologic profile, a higher tendency for chronic infections, mostly of the skin and respiratory tract as well as a reduced tendency for cancer. Further studies into the mechanisms leading to these findings are still needed.
