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.

中文翻译：

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2 号和 8 号染色体不平衡易位的婴儿严重高钙血症：2p 重复的可能贡献

目标 我们报告了一个婴儿严重高钙血症的罕见病例，该婴儿患有 2 号和 8 号染色体不平衡易位并伴有 2p 重复。在排除了高钙血症的所有可能病因后，我们推测涉及 225 个基因的 2p 重复的潜在贡献。病例介绍 一名 11 个月大的女婴患有全面发育迟缓、发育迟缓 (FTT)、肌张力减退、弱视、便秘和近期呕吐，在偶然诊断出严重高钙血症后入院。实验室显示血清磷酸盐、血清 25 (OH) 维生素 D 水平正常，血清甲状旁腺激素 (PTH) 水平低。尿钙与肌酐比值升高排除了低钙尿性高钙血症的可能性。内分泌评估，包括甲状腺功能测试、促肾上腺皮质激素 (ACTH)、皮质醇、胰岛素样生长因子 1 (IGF-1) 均正常。甲状旁腺激素相关肽 (PTHrP) 水平暂时升高，但骨骼检查、胸部 X 光检查和实验室值包括低 1,25 (OH) 2 胆钙化醇、乳酸脱氢酶 (LDH)、尿酸 (UA)、红细胞沉降率（ESR）排除肉芽肿性疾病和恶性肿瘤。对染色体微阵列 (CMA) 和全外显子组基因测序 (WES) 的进一步评估显示，染色体易位不平衡，2p 重复涉及 225 个基因。婴儿在医疗管理下表现出改善。结论 2p 重复综合征是一种罕见的综合征，其特征是发育迟缓、喂养问题、FTT、肌张力减退、便秘和我们病例中提到的异常面部特征。然而，高钙血症仅在 2p 重复综合征早期报告过一次，这是我们病例的表现特征。在排除了高钙血症的所有常见潜在原因后，我们将这种遗传综合征归因于高钙血症的潜在病因。