title: Recurrent Hyperparathyroidism Due to a Novel CDC73 Splice Mutation.
abstract: The recognition of hereditary causes of primary hyperparathyroidism (pHPT) is important because clinical care and surveillance differ significantly between sporadic and hereditary pHPT. In addition, the increasing number of genetic tests poses a challenge to classify mutations as benign or pathogenic. Functional work-up of variants remains a mainstay to provide evidence for pathogenicity. We describe a 52-year-old male patient with recurrent pHPT since age 35 years. Despite several neck surgeries with complete parathyroidectomy, he experienced persistent pHPT, necessitating repeated surgery for a forearm autotransplant, which finally resulted in unmeasurable parathyroid hormone (PTH) levels. Genetic testing revealed a new CDC73 variant (c.238-8G>A [IVS2-8G>A]), initially classified as a variant of uncertain significance. Parathyroid tissue from the initial surgeries showed loss of heterozygosity. Using an RT-PCR approach, we show that the mutation leads to the use of a cryptic splice site in peripheral mononuclear cells. In addition, a minigene approach confirms the use of the cryptic splice site in a heterologous cell system. The novel c.238-8G>A CDC73 variant activates a cryptic splice site, and the functional data provided justify the classification as a likely pathogenic variant. Our results underscore the importance of functional work-up for variant classification in the absence of other available data, such as presence in disease-specific databases, other syndromic clinical findings, or family history. In addition, the presented case exemplifies the importance to consider a hereditary condition in young patients with pHPT, particularly those with multi-gland involvement. © 2017 American Society for Bone and Mineral Research.
authors.affiliation: Department of Internal Medicine, Division of Metabolism, Endocrinology, and Diabetes, University of Michigan, Ann Arbor, MI, USA.
authors.forename: Namita Ganesh
authors.initials: NG
authors.lastname: Hattangady
authors.affiliation: Department of Internal Medicine, Division of Metabolism, Endocrinology, and Diabetes, University of Michigan, Ann Arbor, MI, USA.
authors.forename: Tremika Le-Shan
authors.initials: TL
authors.lastname: Wilson
authors.affiliation: Department of Surgery, Division of Endocrine Surgery, University of Michigan, Ann Arbor, MI, USA.
authors.forename: Barbra Sue
authors.initials: BS
authors.lastname: Miller
authors.affiliation: Department of Internal Medicine, Division of Metabolism, Endocrinology, and Diabetes, University of Michigan, Ann Arbor, MI, USA.
authors.forename: Antonio Marcondes
authors.initials: AM
authors.lastname: Lerario
authors.affiliation: Department of Internal Medicine, Division of Metabolism, Endocrinology, and Diabetes, University of Michigan, Ann Arbor, MI, USA.|Department of Pathology, University of Michigan, Ann Arbor, MI, USA.
authors.forename: Thomas James
authors.initials: TJ
authors.lastname: Giordano
authors.affiliation: Department of Internal Medicine, Division of Metabolism, Endocrinology, and Diabetes, University of Michigan, Ann Arbor, MI, USA.
authors.forename: Palak
authors.initials: P
authors.lastname: Choksi
authors.affiliation: Department of Internal Medicine, Division of Metabolism, Endocrinology, and Diabetes, University of Michigan, Ann Arbor, MI, USA.
authors.forename: Tobias
authors.initials: T
authors.lastname: Else
mesh_terms: D006801:Humans; D006961:Hyperparathyroidism / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D008297:Male; D008875:Middle Aged; D017354:Point Mutation; D022821:RNA Splice Sites; D025521:Tumor Suppressor Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: C454900:CDC73 protein, human; D022821:RNA Splice Sites; D025521:Tumor Suppressor Proteins
keywords: CDC73; HYPERPARATHYROIDISM; PARAFIBROMIN; SPLICE MUTATION