Incidence,Risk Factors,and Clinical Implications of Delayed Hypoparathyroidism on Postoperative Day two Following Total Thyroidectomy for Papillary Thyroid Carcinoma

Objective: This study aimed to investigate the incidence rates, risk factors, and clinical implications of delayed hypoparathyroidism on postoperative day 2 (POD-2) after total thyroidectomy in patients with papillary thyroid carcinoma.Methods: This study included 410 patients with normal serum intact parathyroid hormone (iPTH) and calcium levels on postoperative day 1 (POD-1) who were classified into 2 groups according to the presence or absence of delayed hypoparathyroidism on POD-2.Results: Of the 410 patients, 98 experienced delayed hypoparathyroidism on POD-2 (23.9%). The significant risk factors for delayed hypoparathyroidism on POD-2 included female gender, age older than 45 years, central lymph node dissection, increased number of excised lymph nodes, and low POD-1 versus preoperative iPTH ratios. Additionally, delayed hypoparathyroidism on POD-2 was found to be a significant risk factor for hypocalcemia on POD-2 and permanent hypoparathyroidism.Conclusion: Prophylactic calcium supplementation and long-term surveillance for permanent hypoparathyroidism should be considered in patients with risk factors for delayed hypoparathyroidism on POD-2.Abbreviations: CI = confidence interval; iPTH = intact parathyroid hormone; OR = odds ratio; POD-1 = postoperative day 1; POD-2 = postoperative day 2; PTC = papillary thyroid carcinoma; ROC = receiver operating characteristic     

TBX1 is responsible for cardiovascular defects in velo-cardio-facial/DiGeorge syndrome

Velo-cardio-facial syndrome (VCFS)/DiGeorge syndrome (DGS) is a human disorder characterized by a number of phenotypic features including cardiovascular defects. Most VCFS/DGS patients are hemizygous for a 1.5-3.0 Mb region of 22q11. To investigate the etiology of this disorder, we used a cre-loxP strategy to generate mice that are hemizygous for a 1.5 Mb deletion corresponding to that on 22q11. These mice exhibit significant perinatal lethality and have conotruncal and parathyroid defects. The conotruncal defects can be partially rescued by a human BAC containing the TBX1 gene. Mice heterozygous for a null mutation in Tbx1 develop conotruncal defects. These results together with the expression patterns of Tbx1 suggest a major role for this gene in the molecular etiology of VCFS/DGS.     

Endothelial neuropilin disruption in mice causes DiGeorge syndrome-like malformations via mechanisms distinct to those caused by loss of Tbx1

The spectrum of human congenital malformations known as DiGeorge syndrome (DGS) is replicated in mice by mutation of Tbx1. Vegfa has been proposed as a modifier of DGS, based in part on the occurrence of comparable phenotypes in Tbx1 and Vegfa mutant mice. Many additional genes have been shown to cause DGS-like phenotypes in mice when mutated; these generally intersect in some manner with Tbx1, and therefore impact the same developmental processes in which Tbx1 itself is involved. In this study, using Tie2Cre, we show that endothelial-specific mutation of the gene encoding the VEGFA coreceptor neuropilin-1 (Nrp1) also replicates the most prominent terminal phenotypes that typify DGS. However, the developmental etiologies of these defects are fundamentally different from those caused by absence of TBX1. In Tie2Cre/Nrp1 mutants, initial pharyngeal organization is normal but subsequent pharyngeal organ growth is impaired, second heart field differentiation is normal but cardiac outflow tract cushion organization is distorted, neural crest cell migration is normal, and palatal mesenchyme proliferation is impaired with no change in apoptosis. Our results demonstrate that impairment of VEGF-dependent endothelial pathways leads to a spectrum of DiGeorge syndrome-type malformations, through processes that are distinguishable from those controlled by Tbx1.     

Oncogene Panel Sequencing Analysis Identifies Candidate Actionable Genes in Advanced Well-Differentiated Gastroenteropancreatic Neuroendocrine Tumors

Objective: To report the rate of candidate actionable somatic mutations in patients with locally advanced and metastatic gastro-enteropancreatic (GEP) neuroendocrine tumors (NET) and of other genetic alterations that may be associated with tumorigenesis.Methods: A phase II mutation targeted therapy trial was conducted in patients with advanced well-differentiated G1/G2 GEP-NET. Mutations found in the mTOR pathway-associated genes led to treatment with the mTOR inhibitor everolimus, and were defined as actionable. Tumor deoxyribonucleic acid (DNA) from GEP-NET were sequenced and compared with germline DNA, using the OncoVAR-NET assay, designed for hybrid capture sequencing of 500 tumor suppressor genes and oncogenes. Somatic variants were called and copy-number (CN) variant analysis was performed.Results: Thirty patients (14 small-intestine, 8 pancreatic, 3 unknown primary NET, and 5 of other primary sites) harbored 37 lesions (4 patients had DNA of multiple lesions sequenced). Only 2 patients with sporadic NET (n = 26) had an actionable mutation leading to treatment with everolimus. Driver somatic mutations were detected in 18 of 30 patients (21/37 lesions sequenced). In the remaining samples without a driver mutation, CN alterations were found in 11/16 tumors (10/12 patients), including CN loss of chromosome (Chr) 18 (P<.05), CN gain of Chr 5, and loss of Chr 13. CN losses in Chr 18 were more common in patients without driver mutations detected. Pronounced genetic heterogeneity was detected in patients with multiple lesions sequenced.Conclusion: Genome-wide DNA sequencing may identify candidate actionable genes and lead to the identification of novel target genes for advanced well-differentiated GEP-NET.Abbreviations: Chr = chromosome; CN = copy number; DNA = deoxyribonucleic acid; FDA = Food and Drug Administration; GEP = gastro-enteropancreatic; MEN-1 = multiple endocrine neoplasia syndrome type 1; mTOR = mammalian target of rapamycin; NET = neuroendocrine tumor; PFS = progression-free survival; PNET = pancreatic neuroendocrine tumors; SINET = small-intestine neuroendocrine tumor     

An Open-Label Extension Study of Parathyroid Hormone Rhpth(1-84) in Adults with Hypoparathyroidism

Objective: Hypoparathyroidism is characterized by inadequate parathyroid hormone (PTH), resulting in hypocalcemia, hyperphosphatemia, and bone abnormalities. Adults with hypoparathyroidism treated with recombinant human PTH, rhPTH(1-84), in the 24-week, phase III REPLACE study maintained serum calcium despite reductions in oral calcium and active vitamin D. This study assessed the long-term efficacy and safety of rhPTH(1-84) for hypoparathyroidism.Methods: This was a 24-week, open-label, flexible-dose extension study of REPLACE (REPEAT) conducted in 3 outpatient centers in Hungary. Patients who previously completed or enrolled in REPLACE received 50 μg/day rhPTH(1-84), escalated to 75 and then to 100 μg/day, if needed, to reduce active vitamin D and oral calcium. The primary endpoint was ≥50% reduction in oral calcium (or ≤500 mg/day) and active vitamin D (or calcitriol ≤0.25 μg/day or alfacalcidol ≤0.50 μg/day) with normocalcemia.Results: Twenty-four patients (n = 16 previously treated with rhPTH[1-84]; n = 8 rhPTH[1-84]-naïve) were enrolled and completed the study. At Week 24, 75% of patients (95% confidence interval [CI], 53.3–90.2%) achieved the study endpoint; 58% eliminated oral calcium and active vitamin D. Urinary calcium, serum phosphate, and calcium × phosphate (Ca × P) product decreased by Week 24. Mean serum bone turnover markers increased with rhPTH(1-84). Treatment-emergent adverse events (TEAEs) were reported by 92% of patients. No serious adverse events (AEs) occurred.Conclusion: This study used a simplified treatment algorithm intended to better mimic typical clinical practice and demonstrated the extended efficacy and safety of rhPTH(1-84) in patients with hypoparathyroidism and confirmed the REPLACE findings. Sustained rhPTH(1-84) efficacy up to 48 weeks was observed despite treatment interruption between studies.Abbreviations:AE = adverse eventBMD = bone mineral densityBSAP = bone-specific alkaline phosphataseBTM = bone turnover markerCa × P product = calcium × phosphate productCTX = cross-linked C-telopeptide of type 1 collagenOCN = osteocalcin25(OH)D = 25-hydroxyvitamin DP1NP = aminoterminal propeptide of type 1 collagenPTH = parathyroid hormonerhPTH(1-84) = recombinant human parathyroid hormoneTEAE = treatment-emergent adverse eventULN = upper limit of normal     

The Role of Heteroplasmy in the Diagnosis and Management of Maternally Inherited Diabetes and Deafness

Objective: Maternally inherited diabetes and deafness (MIDD) is a rare diabetic syndrome mainly caused by a point mutation in the mitochondrial DNA (mtDNA), mt3243 adenine to guanine (A>G). The objective of this paper is to review the genetic inheritance, clinical manifestations, and treatment of patients with MIDD.Methods: The current review used a literature search of scientific papers on this rare syndrome.Results: mtDNA is primarily inherited through the maternal oocyte; therefore, the genetic abnormalities in MIDD are associated with maternal inheritance. Mitochondria contain circular mtDNA, which codes for various mitochondrial genes. The mtDNA can be heteroplasmic, containing more than one type of mtDNA sequence; if one of the mtDNAs contains the mt3243 A>G mutation, a patient may develop MIDD. Patients can inherit different amounts of mutated mtDNA and normal mtDNA that affect the severity of the clinical manifestations of MIDD. The most common clinical manifestations include diabetes mellitus, deafness, ophthalmic disease, cardiac disease, renal disease, gastrointestinal disease, short stature, and myopathies. In order to effectively treat patients with MIDD, it is important to recognize the underlying pathophysiology of this specific form of diabetes and the pathophysiology associated with the organ-specific complications present in this disease.Conclusion: The heteroplasmic inheritance of mutated mtDNA plays an important role in the clinical manifestations of various mitochondrial diseases, specifically MIDD. This review will alert endocrinologists of the signs and symptoms of MIDD and important clinical considerations when managing this disease.Abbreviations: ATP = adenosine triphosphate; CoQ10 = coenzyme Q10; MELAS = mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke; MIDD = maternally inherited diabetes and deafness; mtDNA = mitochondrial DNA; tRNA = transfer ribonucleic acid; ROS = reactive oxygen species; T2DM = type 2 diabetes mellitus     

Germline GCM2 Mutation Screening in Chinese Primary Hyperparathyroidism Patients

Objective: Glial cell missing 2 (GCM2), the critical regulator in the development of parathyroid glands, has been associated with the pathogenesis of primary hyperparathyroidism (PHPT). Relevant data in Chinese and other Asian populations are still lacking. This study aimed to screen the germline mutations of GCM2 in Chinese PHPT patients.Methods: A total of 232 patients diagnosed with PHPT at the Peking Union Medical College Hospital from July, 2016, to February, 2019, were screened using targeted next-generation sequencing to identify rare variants of 8 candidate genes associated with PHPT, including GCM2. Luciferase assays were performed to determine the functional impact of the GCM2 variants.Results: Four male patients were found to carry 3 rare missense variants of the GCM2 gene, including c.1162A>G (p.K388E), c.1144G>A (p.V382M), and c.1247A>G (p.Y416C). Two variants (p.K388E and p.V382M) located within a highly conserved region were associated with GCM2 transactivation function. The 2 cases carrying the p.K388E mutation had a pathology of carcinoma, and the case with the p.V382M mutation had atypical adenoma.Conclusion: This study determined an overall GCM2 gain-of-function mutation frequency of 1.3% in a relatively large-sample-sized Chinese PHPT cohort and supported a higher malignant tendency in cases carrying activating GCM2 mutations. Hence, preoperative screening for these GCM2 mutations might be beneficial to treatment decisions, and longer follow-up for such patients is recommended.     

NK4 Antagonizes Tbx1/10 to Promote Cardiac versus Pharyngeal Muscle Fate in the Ascidian Second Heart Field

The heart and head muscles share common developmental origins and genetic underpinnings in vertebrates, including humans. Parts of the heart and cranio-facial musculature derive from common mesodermal progenitors that express NKX2-5, ISL1, and TBX1. This ontogenetic kinship is dramatically reflected in the DiGeorge/Cardio-Velo-Facial syndrome (DGS/CVFS), where mutations of TBX1 cause malformations in the pharyngeal apparatus and cardiac outflow tract. Cardiac progenitors of the first heart field (FHF) do not require TBX1 and segregate precociously from common progenitors of the second heart field (SHF) and pharyngeal muscles. However, the cellular and molecular mechanisms that govern heart versus pharyngeal muscle specification within this lineage remain elusive. Here, we harness the simplicity of the ascidian larva to show that, following asymmetric cell division of common progenitors, NK4/NKX2-5 promotes GATAa/GATA4/5/6 expression and cardiac specification in the second heart precursors by antagonizing Tbx1/10-mediated inhibition of GATAa and activation of Collier/Olf/EBF (COE), the determinant of atrial siphon muscle (ASM) specification. Our results uncover essential regulatory connections between the conserved cardio-pharyngeal factor Tbx1/10 and muscle determinant COE, as well as a mutual antagonism between NK4 and Tbx1/10 activities upstream of GATAa and COE. The latter cross-antagonism underlies a fundamental heart versus pharyngeal muscle fate choice that occurs in a conserved lineage of cardio-pharyngeal progenitors. We propose that this basic ontogenetic motif underlies cardiac and pharyngeal muscle development and evolution in chordates.     

Identifying Parathyroid Hormone Disorders and their Phenotypes through a Bone Health Screening Panel: It's not Simple Vitamin D Deficiency!

Objectives: To determine the utility of bone health screening panels in identifying disorders of parathyroid gland secretions.Methods: A retrospective analysis of biochemical parameters in a bone health screening panel (BHSP) was conducted. Low and high cutoffs were applied to determine hypofunctioning and hyperfunctioning conditions related to parathyroid hormone. Clinical phenotypes of parathyroid gland abnormalities were determined using a combination of levels of calcium, 25-hydroxyvitamin D, and intact parathyroid hormone (iPTH). A PTH nomogram was applied to calculate the maximum expected PTH for existing levels of 25-hydroxyvitamin D. Medical records of patients were reviewed for clinical validation of biochemical findings.Results: Sixty-eight percent of subjects showed abnormal PTH secretion. Primary hyper- and hypoparathyroidism were detected in 1% (n = 5) and 0.4% (n = 2) of subjects, respectively. Normocalcemic hyperparathyroidism and hypercalcemia with inappropriately high-normal PTH were identified in 8.5% (n = 37) and 2% (n = 10) of subjects, respectively. All subjects with primary and normocalcemic hyperparathyroidism had higher measured PTH than calculated maximum PTH using the PTH nomogram. Secondary hyperparathyroidism and functional hypoparathyroidism were present in 18% (n = 88) and 39% (n = 194) of subjects, respectively. High prevalence of bone pains, renal stones, and low bone mineral density were identified in patients with abnormal PTH secretion.Conclusion: Panel testing is useful in early diagnosis of metabolic bone disorders related to PTH. A BHSP helps identify normocalcemic hyperparathyroidism and hypercalcemia with inappropriately high PTH.Abbreviations:25OHD = 25-hydroxyvitamin DAKUH = Aga Khan University HospitalBHSP = bone health screening paneliPTH = intact parathyroid hormonemaxPTH = maximum parathyroid hormoneMBD = metabolic bone diseaseNCHPT = normocalcemic hyperparathyroidismPHPT = primary hyperparathyroidismPTH = parathyroid hormoneSHPT = secondary hyperparathyroidismVDD = vitamin D deficiency     

DiGeorge Syndrome Gene tbx1 Functions through wnt11r to Regulate Heart Looping and Differentiation

DiGeorge syndrome (DGS) is the most common microdeletion syndrome, and is characterized by congenital cardiac, craniofacial and immune system abnormalities. The cardiac defects in DGS patients include conotruncal and ventricular septal defects. Although the etiology of DGS is critically regulated by TBX1 gene, the molecular pathways underpinning TBX1''s role in heart development are not fully understood. In this study, we characterized heart defects and downstream signaling in the zebrafish tbx1^−/− mutant, which has craniofacial and immune defects similar to DGS patients. We show that tbx1^−/− mutants have defective heart looping, morphology and function. Defective heart looping is accompanied by failure of cardiomyocytes to differentiate normally and failure to change shape from isotropic to anisotropic morphology in the outer curvatures of the heart. This is the first demonstration of tbx1''s role in regulating heart looping, cardiomyocyte shape and differentiation, and may explain how Tbx1 regulates conotruncal development in humans. Next we elucidated tbx1''s molecular signaling pathway guided by the cardiac phenotype of tbx1^−/− mutants. We show for the first time that wnt11r (wnt11 related), a member of the non-canonical Wnt pathway, and its downstream effector gene alcama (activated leukocyte cell adhesion molecule a) regulate heart looping and differentiation similarly to tbx1. Expression of both wnt11r and alcama are downregulated in tbx1^−/− mutants. In addition, both wnt11r ^−/− mutants and alcama morphants have heart looping and differentiation defects similar to tbx1^−/− mutants. Strikingly, heart looping and differentiation in tbx1^−/− mutants can be partially rescued by ectopic expression of wnt11r or alcama, supporting a model whereby heart looping and differentiation are regulated by tbx1 in a linear pathway through wnt11r and alcama. This is the first study linking tbx1 and non-canonical Wnt signaling and extends our understanding of DGS and heart development.     

Role of Prophylactic Central Compartment Lymph Node Dissection on the Outcome Of Patients With Papillary Thyroid Carcinoma and Synchronous Ipsilateral Cervical Lymph Node Metastases

Objective: Prophylactic central compartment lymph node dissection (pCCND) results in a higher percentage of surgical-related complications. To date, no evidence of the impact of pCCND on the clinical outcome of papillary thyroid carcinoma (PTC) patients with synchronous ipsilateral cervical lymph node metastases has been reported.Methods: We evaluated all consecutive patients affected by PTC and synchronous ipsilateral cervical, but without evidence of central compartment, lymph node metastases. We selected 54 consecutive patients (group A) treated by total thyroidectomy, ipsilateral cervical lymph node dissection, and pCCND and 115 patients (group B) matched for sex, age at diagnosis, number and dimension of the metastatic lateral cervical lymph nodes, without pCCND. Clinical outcome after a median of 5 years and surgical-related complications were assessed.Results: The two groups were completely similar in terms of clinical features. Clinical outcomes showed a higher percentage of biochemical and indeterminate but not structural response in group B. Group B required significantly more radioiodine treatments, but no difference was shown in the need to repeat surgery for recurrences. Conversely, the prevalence of permanent hypoparathyroidism was significantly higher in group A (14.8%) than in group B (4.3%).Conclusion: In PTC patients with synchronous ipsilateral cervical lymph node metastases, in absence of clinically evident lymph node metastases of the central compartment, performing pCCND does not improve the 5-year outcome in terms of structural disease, despite a greater number of ¹³¹I treatments. However, pCCND is severely affected by a higher percentage of permanent hypoparathyroidism, even in the hands of expert surgeons.Abbreviations: IQR = interquartile range; pCCND = prophylactic central compartment lymph node dissection; PTC = papillary thyroid carcinoma; Tg = thyroglobulin; US = ultrasound     

Whole Exome Sequencing Reveals Homozygous Mutations in RAI1, OTOF,and SLC26A4 Genes Associated with Nonsyndromic Hearing Loss in Altaian Families (South Siberia)

Hearing loss (HL) is one of the most common sensorineural disorders and several dozen genes contribute to its pathogenesis. Establishing a genetic diagnosis of HL is of great importance for clinical evaluation of deaf patients and for estimating recurrence risks for their families. Efforts to identify genes responsible for HL have been challenged by high genetic heterogeneity and different ethnic-specific prevalence of inherited deafness. Here we present the utility of whole exome sequencing (WES) for identifying candidate causal variants for previously unexplained nonsyndromic HL of seven patients from four unrelated Altaian families (the Altai Republic, South Siberia). The WES analysis revealed homozygous missense mutations in three genes associated with HL. Mutation c.2168A>G (SLC26A4) was found in one family, a novel mutation c.1111G>C (OTOF) was revealed in another family, and mutation c.5254G>A (RAI1) was found in two families. Sanger sequencing was applied for screening of identified variants in an ethnically diverse cohort of other patients with HL (n = 116) and in Altaian controls (n = 120). Identified variants were found only in patients of Altaian ethnicity (n = 93). Several lines of evidences support the association of homozygosity for discovered variants c.5254G>A (RAI1), c.1111C>G (OTOF), and c.2168A>G (SLC26A4) with HL in Altaian patients. Local prevalence of identified variants implies possible founder effect in significant number of HL cases in indigenous population of the Altai region. Notably, this is the first reported instance of patients with RAI1 missense mutation whose HL is not accompanied by specific traits typical for Smith-Magenis syndrome. Presumed association of RAI1 gene variant c.5254G>A with isolated HL needs to be proved by further experimental studies.