ESPE2024 Poster Category 2 Late Breaking (107 abstracts)
Identification of GNAS somatic variants in whole blood dna from patients with ovarian-origin peripheral precocious puberty using droplet digital pcr
Aline Guimaraes Faria 1 , Luciana R Montenegro 1 , Alexander Augusto Lima Jorge 1,2 , Regina Matsunaga Martin 1 , Maria Candida B. V. Fragoso 3 , Flavia R Tinano 1 , Carlos E Seraphim 1 , Ana Pinheiro Machado Canton 1 , Larissa Garcia Gomes 1 , Gabriel A Martos-Moreno 4 , Irene Tarjuelo García 5 , Atilano Carcavilla 6 , Mireia Tirado-Capistros 7 , Nadja Christina Souza-Pinto 8 , Jesús Argente 4,9 , Berenice Bilharinho Mendonca 1,10 , Ana Claudia Latronico 1 & Vinicius Nahime Brito 1
1Unidade de Endocrinologia do Desenvolvimento, Laboratório de Hormônios e Genética Molecular LIM/42, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, 05403-900, Sao Paulo, Brazil. 2Unidade de Endocrinologia Genética, Laboratório de Endocrinologia Celular e Molecular LIM/25, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, 05403-900, Sao Paulo, Brazil. 3Unidade de Adrenal, Laboratório de Hormônios e Genética Molecular LIM/42, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, 05403-900, Sao Paulo, Brazil. 4Department of Pediatrics & Pediatric Endocrinology, Hospital Infantil Universitario Niño Jesús, Instituto de Investigación La Princesa. CIBER Fisiopatología de la obesidad y nutrición (CIBEROBN), Instituto de Salud Carlos III. 28009, Madrid, Spain. 5Servicio de Endocrinología Pediátrica, Hospital Universitario Sanitas La Moraleja, Madrid, Spain. 6Department of Pediatric Endocrinology, Skeletal Dysplasia Multidisciplinary Unit (UMDE-ERN BOND). European Research Network on Rare BONe Disorders (ERN- BOND), Hospital Universitario La Paz., Madrid, Spain. 7Servicio de Pediatría, Hospital de la Santa Creu i Sant Pau. Department of Pediatrics, Obstetrics & Gynecology and Preventive Medicine and Public Health. Universitat Autònoma de Barcelona, Institut de Recerca Biomèdica Sant Pau (IIB-Sant Pau)., Barcelona, Spain. 8Lab. Genética Mitocondrial, Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Sao Paulo, Brazil. 9IMDEA. Food Institute, CEIUAM+CSI. Cantoblanco, 28049, Madrid, Spain. 10Laboratório de Sequenciamento em Larga Escala (SELA), Faculdade de Medicina da Universidade de São Paulo, Sao Paulo, Brazil
Background: GNAS activating mutations are the genetic basis of McCune-Albright syndrome (MAS). Peripheral precocious puberty (PPP) due to functional ovarian cysts, with or without MAS features, denotes a potential GNAS -related disorder.
Aim: To explore GNAS somatic mutations (p.R201C/H) in peripheral leukocyte DNA using ddPCR in girls with ovarian-origin PPP with or without MAS.
Patients and Methods: 38 girls with ovarian-origin PPP, with (n = 27) or without (n = 11) MAS features, were enrolled. DNA from peripheral blood underwent ddPCR analysis. Two ddPCR mutation detection assays targeted the p.R201C or p.R201H variants. Following amplification, fluorescence of each droplet was read on a 200 Droplet Digital PCR system (Bio-Rad). Quantasoft software (Bio-Rad) was used to determine the total positive droplets in the original sample. Fractional abundance (FA), a percentage of mutated alleles of the total alleles, was calculated. The limit of detection after validation was set at 0.1% of FA.
Results: Clinical and laboratory presentations of pubertal development were comparable in girls with PPP with (n = 27) or without (n = 11) MAS features, except for more frequent vaginal bleeding episodes in the MAS group. Among 27 patients with MAS, 14 had the classical triad of MAS, while 13 exhibited two MAS features. Of those 27 girls, fibrous dysplasia was present in 21, café au lait spots in 19, and hyperthyroidism in 3 girls (with classical MAS triad). GNAS variants (p.R201C/H) were identified in whole blood DNA of 8/14 (57.1%) girls with MAS with the complete triad, 5/13 (38.4%) with MAS with 2 features, and 3/11 (27.3%) with only PPP without other MAS features. A significant positive correlation was identified between a positive test and the number of clinical features (P < 0.05). The median FA of GNAS mutated alleles was 0.58%, ranging from 0.1% to 18.9%. The higher median FA was shown in the group with MAS triad (1.2%), followed by MAS with 2 features (0.33%), while the lower FA was identified in those patients with only PPP (0.17%), with no statistically significant difference (P =0.07).
Conclusion: This study provides valuable insights into detecting GNAS activating mutations in DNA from peripheral leukocytes using ddPCR in patients with PPP, with or without MAS features, thereby widening the genetic diagnosis and spectrum of GNAS -related disorders.
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