LAUSR

Abstract Objectives We report an uncommon case of severe hypercalcemia in an infant with unbalanced translocation of chromosomes 2 and 8 with 2p duplication. After ruling out all the possible etiologies of hypercalcemia, we speculated a potential contribution of 2p duplication involving 225 genes. Case presentation An 11-month old female infant with global developmental delay, failure to thrive (FTT), hypotonia, amblyopia, constipation, and recent onset emesis was admitted to the hospital after an incidental diagnosis of severe hypercalcemia. Labs revealed normal serum phosphate, serum 25 (OH) vitamin D levels, and low serum parathyroid hormone (PTH) level. Elevated urinary calcium to creatinine ratio ruled out the possibility of hypocalciuric hypercalcemia. Endocrinological evaluations, including thyroid function test, Adrenocorticotropic hormone (ACTH), Cortisol, Insulin like growth factor 1 (IGF-1) were all normal. Transient elevation of parathyroid hormone related peptide (PTHrP) level was noted, but skeletal survey, chest X-ray and lab values including low 1,25 (OH)2 cholecalciferol, lactate dehydrogenase (LDH), uric acid (UA), erythrocyte sedimentation rate (ESR) excluded granulomatous diseases and malignancies. Further evaluation with chromosomal microarray (CMA) and whole exome gene sequencing (WES) showed an unbalanced chromosomal translocation with 2p duplication involving 225 genes. The infant showed an improvement with medical management. Conclusions 2p duplication syndrome is a rare syndrome characterized by developmental delay, feeding problems, FTT, hypotonia, constipation, and unusual facial features as noted in our case. However, hypercalcemia has been only reported once earlier in 2p duplication syndrome, which was the presenting feature of our case. We attributed this genetic syndrome as an underlying etiology for hypercalcemia after ruling out all the common potential causes of hypercalcemia.