Hypercalcitoninaemia in Pseudohypo Parathyroidism Type 1A and Type 1B
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ID: 18-0125 -18-0125 M P Yavropoulou and Calcitonin in ID: 18-0125; January 2019 others pseudohypoparathyroidism DOI: 10.1530/EDM-18-0125 Hypercalcitoninaemia in pseudohypo parathyroidism type 1A and type 1B Maria P Yavropoulou1, Efstathios Chronopoulos2, George Trovas3, Emmanouil Avramidis2, Francesca Marta Elli4, Giovanna Mantovani4, Pantelis Zebekakis5 and John G Yovos5 11stPropaedeuticDepartmentofInternalMedicine,LAIKOGeneralHospitalofAthens,22nd Orthopaedic Correspondence Department,KonstantopouleioGeneralHospital,3LaboratoryforResearchoftheMusculoskeletalSystem,Th should be addressed Garofalidis,NationalandKapodistrianUniversityofAthens,Athens,Greece,4Endocrinology Unit, Department of to M P Yavropoulou ClinicalSciencesandCommunityHealth,FondazioneIRCCSCa’GrandaOspedaleMaggiorePoliclinico,Universityof Email Milan, Milan, Italy, and 51stDepartmentofInternalMedicine,AHEPAUniversityHospital,Thessaloniki,Greece maria.yavropoulou.my@ gmail.com Summary Pseudohypoparathyroidism(PHP)isaheterogeneousgroupofrareendocrinedisorderscharacterisedbynormalrenal functionandrenalresistancetotheactionoftheparathyroidhormone.Type1A(PHP1A),whichisthemostcommon variant,alsoincludedevelopmentalandskeletaldefectsnamedasAlbrighthereditaryosteodystrophy(AHO).Wepresent twocases,a54-anda33-year-oldmalediagnosedwithPHPwhowerereferredtousforpersistentlyhighlevelsofserum calcitonin.AHOandmultinodulargoitrewerepresentinthe54-year-oldmale,whilethesecondpatientwasfreeofskeletal deformitiesandhisthyroidglandwasofnormalsizeandwithoutnodularappearance.WeperformedGNASmolecular analysis(methylationstatusandcopynumberanalysisbyMS-MLPA)ingenomicDNAsamplesforbothpatients.The analysisrevealedanovelmissensevariantc.131T>Gp.(Leu44Pro)affectingGNASexon1,inthepatientwiththeclinical diagnosisofPHP1A.Thisaminoacidchangeappearstobeinaccordancewiththeclinicaldiagnosisofthepatient.The genomicDNAanalysisofthesecondpatientrevealedthepresenceoftherecurrent3-kbdeletionaffectingtheimprinting controlregionlocalisedintheSTX16regionassociatedwiththelossofmethylation(LOM)attheGNASA/Bdifferentially methylatedregionandconsistentwiththediagnosisofanautosomaldominantformofPHPtype1B(PHP1B).In conclusion,hypercalcitoninaemiamaybeencounteredinPHP1AandPHP1Bevenintheabsenceofthyroidpathology. Learning points: •• Wedescribeanovelmissensevariantc.131T>Gp.(Leu44Pro)affectingGNASexon1asthecauseofPHP1A. •• HypercalcitoninaemiainPHP1Aisconsideredanassociatedresistancetocalcitonin,assuggestedbythe generalisedimpairmentofGsα-mediated hormone signalling.GNASmethylationdefects,asintypePHP1B,without thyroid pathology can also present with hypercalcitoninaemia. Background Pseudohypoparathyroidism (PHP) is a heterogeneous not widely accepted, as a term encompassing all disorders group of rare endocrine disorders characterised by normal related to this pathway (1). renal function and resistance to the renal action of The genetic background of the disease includes parathyroid hormone. Inactivating PTH/PTHrp signalling mutations and/or epigenetic changes at the complex disorders (iPPSD) has been recently suggested, although GNAS gene on chromosome 20q13.3 that undergoes This work is licensed under a Creative Commons © 2019 The authors https://edm.bioscientifica.com/ Attribution-NonCommercial-NoDerivs 3.0 PublishedbyBioscientificaLtd UnportedLicense. Downloaded from Bioscientifica.com at 09/29/2021 03:06:57PM via free access M P Yavropoulou and Calcitonin in ID: 18-0125; January 2019 others pseudohypoparathyroidism DOI: 10.1530/EDM-18-0125 parent-specific methylation changes at several sites. endocrine clinic for further investigation of their GNAS gene encodes alpha subunit of the stimulatory persistently high levels of serum calcitonin. guanine nucleotide (Gsα) part of the signalling pathway of G-proteins-coupled receptors (GPCRs) and splice variants Case presentation as well as an antisense transcript. Because of the much reduced paternal Gsα expression in certain tissues, such as Case 1 was a 54-year-old male complaining of weakness, the proximal renal tubules, thyroid and pituitary, there is fatigue and periodic headache. His general practitioner little or no Gsα protein in the presence of maternal GNAS asked for consultancy from an endocrinologist seeking mutations. Furthermore, since a wide variety of hormonal for further investigation of his hypercalcitoninaemia on peptides such as GHRH, TSH, FSH, LH or calcitonin (CT) the ground of multinodular goitre (calcitonin >100 pg/mL act through GPCRs in different tissues, it is clear that in repeated measurements). The physical examination patients with PHP may present with additional hormone revealed an obese person (BMI: 39.7) with short stature dysfunctions. (height: 165 cm) (Table 1), round face, stocky appearance Heterozygous maternal deletions within the STX16 with notable facial puffiness and brachydactyly of hands gene, which are associated with loss of mutation (LOM) and feet. There was no report of his physical appearance at exon A/B also reduce Gsα expression, thus leading to up to the day he visited our department. An epicranial hormonal resistance. Other genes that may be involved in subcutaneous ossification was removed in the fronto- this group of diseases are PRKAR1A and PDE4D (2). parietal area of the head 6 years before. At that time, As there is considerable variability in tissue he was found to have asymptomatic hypocalcaemia responsiveness to Gsα protein deficiency, mainly due and started treatment with active vitamin D analogues to differences in the quantity of cAMP that is necessary (1.0 μg of 1a-OH vitamin D) and oral calcium carbonate to activate the physiological responses in each tissue or 2 g/day, which he continued up to the day we examined absence of imprinting in target tissues, other hormones the patient. Ten years before, he was diagnosed with such as ACTH and vasopressin that also stimulate Gsα chronic lymphocytic thyroiditis (Hashimoto’s) and protein are not usually impaired (3), although ACTH multinodular goitre and he was treated since then with resistance has been described before in PHP type 1 (4). 225 μg of levothyroxine. His blood pressure was normal There are several variants of PHP, including type (125/82 mmHg) and the pulse rate was 78/min. The tendon 1A (PHPIA), type 1B (PHP1B), type 1C (PHP1C), type 2 reflexes were normal. The X-rays of the hands revealed (PHP2) and pseudopseudohypoparathyroidism (PPHP). shortening of the metacarpals with epiphyseal widening, The phenotype of PHP1A, which is the most commonly conical configuration of the phalangeal heads, osteopenic found variant (5), and PHP1C include multiple hormone appearance, as well as stenosis of the phalangeal joint resistance and skeletal defects such as short stature, space and hardening of the joint surfaces. obesity, round face, subcutaneous ossifications and His laboratory workup revealed hypocalcaemia and brachydactyly, collectively named as Albright's hereditary phosphate levels slightly above normal with elevated osteodystrophy (AHO) (6). PHP1B is pathogenetically serum PTH and calcitonin levels (Table 2). Based on the linked to imprinting methylation defects at the GNAS laboratory results and his clinical appearance, we diagnosed locus resulting in lack of expression of the maternal allele PHP1A with AHO. To confirm our diagnosis we performed almost exclusively in the renal tissue (7) and usually the Howard–Ellsworth test with s.c. administration of lack AHO, but may present with additional hormone recombinant 1-34 N-terminal fragment of endogenous dysfunctions, most frequently TSH resistance (8). human parathyroid hormone (INN-teriparatide, Forsteo, Pseudopseudohypoparathyroidism, on the other Pharmaserve-Lilly, Inc). Administration of 20 μg of hand, is a clinical entity characterised by AHO phenotype INN-teriparatide did not change urine cAMP and PO4 without hormone resistance and is linked to GNAS levels analysed on samples voided every 30 min for mutations in the paternally inherited allele (7). 3 h post injection (Fig. 1). Urinary cAMP is measured Hypercalcitoninaemia has been sporadically described using an ELISA (Cayman Chemicals), according to the in patients with PHP1A and IB (9, 10, 11), but the exact manufacturer’s instructions. The standard curve range for pathogenetic mechanism and its relation to the future this assay is 0.078–10 pmol/mL, with a sensitivity (80% B/ development of medullary thyroid carcinoma (MTC) B0) of 0.1 pmol/mL. remain unknown. We present two cases of PHP with Case 2 was a 33-year-old male complaining of distinct phenotypes that were referred to our outpatient generalised muscular weakness, pain and tetany (twitches https://edm.bioscientifica.com/ 2 Downloaded from Bioscientifica.com at 09/29/2021 03:06:57PM via free access M P Yavropoulou and Calcitonin in ID: 18-0125; January 2019 others pseudohypoparathyroidism DOI: 10.1530/EDM-18-0125 Table 1 Clinical presentation of cases. Case 1 Case 2 Age 54 33 Bodyweight(kg) 108 78 Height(cm) 165 177 BMI 39.7 24.9 AHO Present Absent Main symptoms Weakness,fatigue Weakness,tetany Medical record Epicranialsubcutaneousossification Gilbertsyndrome,bilateralinguinalhernia, mild scoliosis Thyroid ultrasound Multinodular goitre Normal morphology Familyhistoryofpseudohypoparathyroidism Absent Absent Brown tumours Absent Absent Historyofbasicgangliacalcification/seizures Absent Absent of the quadriceps) while lying down and was referred to us patient suffered from Gilbert syndrome, bilateral inguinal for his persistently high levels of calcitonin in the absence hernia