[Pseudohypoparathyroidism or hypoparathyroidism? A misleading clinical presentation]

We report the case of a 27-year old woman who presented hypocalcemia and hyperphosphoremia during her first pregnancy. Her phenotype was in favor of Albright's hereditary osteodystrophy: short stature, obesity, round face, brachymetacarpy and mental retardation. However, the diagnosis of pseudohypopara thyroidism type Ia was ruled out due to low PTH level (10 pg/ml). The patient's 22q11 microdeletion was suspected and identified because of the association of severe neonatal hypocalcemia, abnormal face and renal malformation in her children. Deletion 22q11 leads to various syndromes, including Di George syndrome, also referred to as CATCH 22 syndrome (Cardiac defect (C), Abnormal face (A), Thymic hypoplasia (T), Cleft palate (C) and Hypocalcemia (H)). Retrospectively, the patient presented with symptoms suggestive of CATCH 22: abnormal face, hypernasal voice suggestive of velopharyngeal insufficiency, mental retardation, recurrent otitis in childhood. It is also noteworthy that there was an idiopathic thrombocytopenic purpura. In conclusion, while the phenotype was suggestive of Albright's hereditary osteodystrophy, the constatation of a low PTH level would cast doubt on this diagnosis. Furthermore, the 22q11 microdeletion should be searched by FISH (Fluorescence In Situ Hybridization) in all patients with hypopara thyroidism of unknown origin, even in the absence of cardiac malformations. Finally, it seems that patients with CATCH 22 would be predisposed to auto-immune disease as a result of thymic dysfunction.