IL12Rβ1 deficiency ranks as the most common form of Mendelian susceptibility to
mycobacteria accounting for 60% of cases. Currently, about 300 cases of IL12Rβ1 have
been reported, among which 2 cases have reported as a finding the presence of
lymphopenia and only 5 cases describe the development of autoimmunity. We present a
case of IL12Rβ1 deficiency with persistent severe lymphopenia associated with clinical
features suggestive of autoimmunity.
A 25-year-old female with no history of consanguinity with medical history of BCGitis at 6
months old manifested by right axillary lymphadenitis. She had have the following infections:
recurrent oral candidiasis since 6 years-old, varicella at 6 years and intestinal tuberculosis
due to Mycobacterium bovis at 14 years treated with antituberculosis drugs. At 15 years-old,
she developed diffuse alopecia and photosensitivity. At the age of 16, she was diagnosed
with IL12Rβ1 deficiency through inborn errors of immunity gene panel and flow cytometry,
initiating treatment with recombinant IFNy. During previous hospital stays and in subsequent
appointments, persistent severe lymphopenia and hypergammaglobulinemia were
documented in multiple paraclinical controls with absolute lymphocyte count up to 360
cells/mm3 that required prophylaxis with trimethoprim with sulfamethoxazole. At 17 years of
age, autoimmune hemolytic anemia was detected and improved with gammaglobulin. At age
20, she developed subclinical hypothyroidism requiring levothyroxine.
Currently, there been reported 5 cases of IL12Rβ1 deficiency associated with autoimmunity.
All cases were detected in adolescence and adulthood. Longer survival has allowed
observation of the natural history of the disease including autoimmunity. This case suggests
that the lack of INFy production due to an abnormality in the β1 subunit of the IL-12 receptor
has a regulatory effect that prevents autoimmune disorders.

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