Hypoparathyroidism and insulin-dependent diabetes mellitus in a patient with Kearns-Sayre syndrome harbouring a mitochondrial DNA deletion

We report a 17-year-old girl with short stature, external ophthalmoplegia, atypical retinal pigmentary degeneration, sensorineural hearing loss, and cardiac conduction defect (Kearns-Sayre syndrome), A large-scale deletion (6741 base pairs) in mitochondrial DNA was found in her muscle specimen, She also had insulin-dependent diabetes mellitus (IDDM). On admission, her plasma glucose level was elevated at 31.0 mmol/l with mild ketoacidosis, and haemoglobinA1c elevated at 16.5%, After improvement of diabetic ketoacidosis, she was placed on insulin 24-30 units/day despite her small body weight of 25 kg, There was reduced excretion of urinary C-peptide at 3.97 nmol/day. In addition, she had idiopathic hypoparathyroidism with a serum calcium level of 2.15 mmol/l, phosphate 1.7 mmol/l, and intact PTH below 10 ng/l. Human leucocyte associated antigen typing showed A24, A26; B54, B61; CW1, CW3; DR8, DR14; DQ1 and DQ3, suggesting that the presence of HLA-A24 and CW3 antigen contributed to the association of IDDM and hypoparathyroidism, similar to Japanese patients with polyglandular autoimmune syndrome, complicated by hypoparathyroidism and IDDM. We suggest that a genetic linkage, as well as mitochondrial dysfunction, may be responsible for the association of the two disease states. This is an extremely rare case of Kearns-Sayre syndrome, presenting in association with IDDM and idiopathic hypoparathyroidism.