Endocrine Abstracts

Introduction: DiGeorge syndrome (DGS) is mainly characterized by congenital heart defects, dysmorphic features, hopolasia of the thymus and parathyroid glands and immunodeficiency. Approximately 10% of patients with DGS have autoimmune disease¹.

Observation: This is a 21-year-old patient, diagnosed with DGS at the age of 14 year old. The diagnosis was suspected on the association of characteristic facial, hypoparathyroidism and a congenital heart defect (a right aortic arch with an aberrant retro-esophageal left subclavian artery). It was confirmed by a genetic study detecting a microdeletion of the T-box transcription factor TBX1. The patient was well balanced on low-dose Alphacalcidol. During follow-up, the patient developed an inaugural diabetic ketosis with Hb1Ac at 12%. The autoimmune type 1 diabetes was confirmed by positive GAD antibodies (>2000 IU/ml). We noted also autoimmune thyroiditis with high anti thyroperoxydase levels (>1000 IU/ml) with normal TSH Level. Antibodies caeliac disease were negative.

Discussion: DGS increases the risk of autoimmunity 10-fold compared with the general population. This may be explained by thymic hypoplasia and the inability of T lymphocytes to recognize peripheral antigens. Thyroid autoimmunity was associated with DGS in 22% of cases². Anti-pancreatic autoimmunity appears to be less frequent and only 3 cases of type 1 diabetes have been published.

Conclusion: The association of autoimmune diseases with DGS remains underestimated and poorly studied. This prompts us to look for them in cases of clinical suspicion and to establish screening recommendations.

References: 1. Gennery AR, Barge D, O’Sullivan JJ, Flood TJ, Abinun M, Cant AJ. Antibody deficiency and autoimmunity in 22q11.2 deletion syndrome. Arch Dis Child 2002; 86: 422–5.2. Lima K, Abrahamsen TG, Wolff AB, et al. Hypoparathyroidismand autoimmunity in the 22q11.2 deletion syndrome. Eur JEndocrinol. 2011;165: 345-352.