Alejandro García-Castaño, Leire Madariaga, Gustavo Pérez de Nanclares, Gema Ariceta, Sonia Gaztambide, Luis Castaño and Spanish Endocrinology Group and Renal Tube Group
Molecular diagnosis is a useful diagnostic tool in calcium metabolism disorders. The calcium-sensing receptor (CaSR) is known to play a central role in the regulation of extracellular calcium homeostasis. We performed clinical, biochemical and genetic characterization of sequence anomalies in this receptor in a cohort of 130 individuals from 82 families with suspected alterations in the CASR gene, one of the largest series described.
The CASR gene was screened for mutations by polymerase chain reaction followed by direct Sanger sequencing.
Presumed CaSR-inactivating mutations were found in 65 patients from 26 families. These patients had hypercalcemia (median: 11.3 mg/dL) but normal or abnormally high parathyroid hormone (PTH) levels (median: 52 pg/mL). On the other hand, presumed CaSR-activating mutations were detected in 17 patients from eight families. These patients had a median serum calcium level of 7.4 mg/dL and hypoparathyroidism (median: PTH 13 pg/mL). Further, common polymorphisms previously associated with high blood ionized calcium levels were found in 27 patients (median calcium: 10.6 mg/dL; median PTH: 65 pg/mL) with no other alterations in CASR. Overall, we found 30 different mutations, of which, 14 have not been previously reported (p.Ala26Ser, p.Cys60Arg, p.Lys119Ile, p.Leu123Met, p.Glu133Val, p.Gly222Glu, p.Phe351Ile, p.Cys542Tyr, p.Cys546Gly, p.Cys677Tyr, p.Ile816Val, p.Ala887Asp, p.Glu934*, p.Pro935_Gln945dup).
Patients with CASR mutations may not fit the classic clinical pictures of hypercalcemia with hypocalciuria or hypocalcemia with hypercalciuria. Molecular studies are important for confirming the diagnosis and distinguishing it from other entities. Our genetic analysis confirmed CaSR disorders in 82 patients in the study cohort.
Nuria Valdés, Elena Navarro, Jordi Mesa, Anna Casterás, Victoria Alcázar, Cristina Lamas, Javier Tébar, Luis Castaño, Sonia Gaztambide and Lluís Forga
Specific germline mutations in the RET proto-oncogene are correlated with clinical features in multiple endocrine neoplasia type 2A (MEN2A); however, data are scarce regarding differences in clinical profiles dependent on the type of nucleotide and amino acid substitution at the same codon. We aimed to analyse differences in clinical risk profiles and outcomes among different amino acids encoded by codon 634.
The study was retrospective and multicentric.
We collected data included in the Spanish Online National Database from patients with MEN2A carrying a RET proto-oncogene mutation on codon 634. The mean follow-up time was 7.6±6.9 years (1–32).
Patients (n=173) from 49 unrelated families were C634Y carriers, and 26 patients from eight different families had C634R mutation. We found higher penetrance of medullary thyroid carcinoma, phaeochromocytoma and hyperparathyroidism (P<0.001, P=0.007 and P<0.001 respectively) in C634R carriers than in C634Y carriers. The Kaplan–Meier estimate of cumulative lymph node and distant metastases rates showed that these events occurred earlier in patients harbouring the C634R mutation (P<0.001). A multivariate adjusted Cox regression analysis indicated that the C634R mutation was an independent factor for persistent/recurrent disease (hazard ratio, 3.17; 95% CI: 1.66–6.03; P<0.001).
Our results suggest that there could be clinical differences caused by different amino acid substitutions at codon 634; specifically, the C634R mutation was associated with a more aggressive MEN2A phenotype than the C634Y mutation.
Eduardo Fernández-Rebollo, Olga Pérez, Cristina Martinez-Bouzas, Maria Carmen Cotarelo-Pérez, Intza Garin, Jose Luis Ruibal, Gustavo Pérez-Nanclares, Luis Castaño and Guiomar Pérez de Nanclares
The phenotypic variability of patients with syndromes presenting with dysmorphism makes clinical diagnosis difficult, leading to an exhaustive genetic study to determine the underlying mechanism so that a proper diagnosis could be established.
To genetically characterize siblings, the older sister diagnosed with Albright hereditary osteodystrophy and the younger one with CHARGE syndrome.
Clinical case report.
Clinical, biochemical, and radiological studies were performed on the family. In addition, molecular genetic studies including sequencing of GNAS, typing of microsatellites on 2q and 21q, and multiplex ligation-dependent probe amplification of subtelomeric regions were performed, as well as confirmatory fluorescent in situ hybridization analysis.
The genetic analysis revealed that both sisters presented a 2q37 deletion due to the maternal unbalanced segregation of a 2;21 translocation.
This is the first report of a 2q37 deletion where differential diagnosis of CHARGE syndrome is needed due to the appearance of choanal atresia.
Eduardo Fernández-Rebollo, Beatriz Lecumberri, Intza Garin, Javier Arroyo, Ana Bernal-Chico, Fernando Goñi, Rosa Orduña, Spanish PHP Group, Luis Castaño and Guiomar Pérez de Nanclares
Type I pseudohypoparathyroidism (PHP-I) can be subclassified into Ia and Ib, depending on the presence or absence of Albright's hereditary osteodystrophy's phenotype, diminished α-subunit of the stimulatory G protein (Gsα) activity and multihormonal resistance. Whereas PHP-Ia is mainly associated with heterozygous inactivating mutations in Gsα-coding exons of GNAS, PHP-Ib is caused by imprinting defects of GNAS. To date, just one patient with PHP and complete paternal uniparental disomy (UPD) has been described.
We sought to identify the underlining molecular defect in twenty patients with parathyroid hormone resistance, hypocalcemia and hyperphosphatemia, and abnormal methylation pattern at GNAS locus.
Microsatellite typing and comparative genome hybridization were performed for proband and parents.
We describe four patients with partial paternal UPD of chromosome 20 involving pat20qUPD in one case, from 20q13.13-qter in two cases, and pat20p heterodisomy plus interstitial 20q isodisomy in one patient.
These observations demonstrate that mitotic recombination of chromosome 20 can also give rise to UPD and PHP, a situation similar to other imprinting disorders, such as Beckwith–Wiedemann syndrome or neonatal diabetes.
Antonio J Martínez-Fuentes, Marcelo Molina, Rafael Vázquez-Martínez, Manuel D Gahete, Luis Jiménez-Reina, Jesús Moreno-Fernández, Pedro Benito-López, Ana Quintero, Andrés de la Riva, Carlos Diéguez, Alfonso Soto, Alfonso Leal-Cerro, Eugenia Resmini, Susan M Webb, Maria C Zatelli, Ettore C degli Uberti, María M Malagón, Raul M Luque and Justo P Castaño
KISS1 was originally identified as a metastasis-suppressor gene able to inhibit tumor progression. KISS1 gene products, the kisspeptins, bind to a G-protein-coupled receptor (KISS1R, formerly GPR54), which is highly expressed in placenta, pituitary, and pancreas, whereas KISS1 mRNA is mainly expressed in placenta, hypothalamus, striatum, and pituitary.
Objective and design
KISS1/KISS1R pituitary expression profile, coupled to their anti-tumoral capacities, led us to hypothesize that this system may be involved in the biology of pituitary tumors. To explore this notion, expression levels of KISS1R and KISS1 were evaluated in normal and adenomatous pituitaries. Additionally, functionality of this system was assessed by treating dispersed pituitary adenoma cells in primary culture with kisspeptin-10 and evaluating intracellular calcium kinetics and apoptotic rate.
Both KISS1 and KISS1R were expressed in normal pituitary, whereas this simultaneous expression was frequently lost in pituitary tumors, where diverse patterns of KISS1/KISS1R expression were observed that differed among distinct types of pituitary adenomas. Measurement of calcium kinetics revealed that kisspeptin-10 elicits a remarkable increase in [Ca2+]i in individual cells from four out of the five GH-producing adenomas studied, whereas cells derived from non-functioning pituitary adenomas (NFPA, n=45) did not respond. In contrast, kisspeptin-10 treatment increased the apoptotic rate in cells derived from both GH-producing and NFPA.
These results provide primary evidence that KISS1 and KISS1R expression can be differentially lost in pituitary tumor subtypes, where this system can exert functional, proapoptotic actions, and thereby offer novel insights to investigate the biology and therapeutic options to treat these tumors.