Pseudohypoparathyroidism is a rare endocrine disorder that can be caused by genetic (mainly maternally inherited inactivating point mutations, although intragenic and gross deletions have rarely been reported) or epigenetic alterations at GNAS locus. Clinical and molecular characterization of this disease is not that easy because of phenotypic, biochemical and molecular overlapping features between both subtypes of the disease. The European Consortium for the study of PHP (EuroPHP) designed the present work with the intention of generating the standards of diagnostic clinical molecular (epi)genetic testing in PHP patients. With this aim, DNA samples of eight independent PHP patients carrying GNAS genetic and/or epigenetic defects (three patients with GNAS deletions, two with 20q uniparental disomy and three with a methylation defect of unknown origin) without GNAS point mutations were anonymized and sent to the five participant laboratories for their routine genetic analysis (methylation-specific (MS)-MLPA, pyrosequencing and EpiTYPER) and interpretations. All laboratories were able to detect methylation defects and, after the data analysis, the Consortium compared the results to define technical advantages and disadvantages of different techniques. To conclude, we propose as first-level investigation in PHP patients copy number and methylation analysis by MS-MLPA. Then, in patients with partial methylation defect, the result should be confirmed by single CpG bisulphite-based methods (ie pyrosequencing), whereas in case of a complete methylation defect without detectable deletion, microsatellites or SNP genotyping should be performed to exclude uniparental disomy 20.

European guidance for the molecular diagnosis of pseudohypoparathyroidism not caused by point genetic variants at GNAS : an EQA study / I. Garin, G. Mantovani, U. Aguirre, A. Barlier, B. Brix, F.M. Elli, K. Freson, V. Grybek, B. Izzi, A. Linglart, G. Perez de Nanclares, C. Silve, S. Thiele, R. Werner. - In: EUROPEAN JOURNAL OF HUMAN GENETICS. - ISSN 1018-4813. - 23:4(2015), pp. 438-444. [10.1038/ejhg.2014.127]

European guidance for the molecular diagnosis of pseudohypoparathyroidism not caused by point genetic variants at GNAS : an EQA study

G. Mantovani
Secondo
;
F.M. Elli;
2015

Abstract

Pseudohypoparathyroidism is a rare endocrine disorder that can be caused by genetic (mainly maternally inherited inactivating point mutations, although intragenic and gross deletions have rarely been reported) or epigenetic alterations at GNAS locus. Clinical and molecular characterization of this disease is not that easy because of phenotypic, biochemical and molecular overlapping features between both subtypes of the disease. The European Consortium for the study of PHP (EuroPHP) designed the present work with the intention of generating the standards of diagnostic clinical molecular (epi)genetic testing in PHP patients. With this aim, DNA samples of eight independent PHP patients carrying GNAS genetic and/or epigenetic defects (three patients with GNAS deletions, two with 20q uniparental disomy and three with a methylation defect of unknown origin) without GNAS point mutations were anonymized and sent to the five participant laboratories for their routine genetic analysis (methylation-specific (MS)-MLPA, pyrosequencing and EpiTYPER) and interpretations. All laboratories were able to detect methylation defects and, after the data analysis, the Consortium compared the results to define technical advantages and disadvantages of different techniques. To conclude, we propose as first-level investigation in PHP patients copy number and methylation analysis by MS-MLPA. Then, in patients with partial methylation defect, the result should be confirmed by single CpG bisulphite-based methods (ie pyrosequencing), whereas in case of a complete methylation defect without detectable deletion, microsatellites or SNP genotyping should be performed to exclude uniparental disomy 20.
albrights hereditary osteodystrophy; imprinting control element; Silver-Russel syndrome; stimulatory g-protein; hormone resistance; methylation defect; epigenetic defects; alpha-subunit; exon A/B; IB
Settore MED/13 - Endocrinologia
2015
9-lug-2014
Article (author)
File in questo prodotto:
File Dimensione Formato  
ejhg2014127a.pdf

accesso riservato

Tipologia: Publisher's version/PDF
Dimensione 837.42 kB
Formato Adobe PDF
837.42 kB Adobe PDF   Visualizza/Apri   Richiedi una copia
Pubblicazioni consigliate

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/243751
Citazioni
  • ???jsp.display-item.citation.pmc??? 12
  • Scopus 24
  • ???jsp.display-item.citation.isi??? 22
social impact