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Paolo C, Andrea G, Elli FM, Rossella G, Erika P, Milena B, Thiele S, Francesca G, Giovanna M, Franco A. A complex pheotype in a girl with a novel heterozygous missense variant (p.Ile56Phe) of the GNAS gene. Orphanet J Rare Dis 2022; 17:83. [PMID: 35197096 PMCID: PMC8867619 DOI: 10.1186/s13023-022-02252-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 02/13/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND GNAS is a complex gene that encodes Gsα, a signaling protein that triggers a complex network of pathways. Heterozygous inactivating mutations in Gsα-coding GNAS exons cause hormonal resistance; on the contrary, activating mutations in Gsα result in constitutive cAMP stimulation. Recent research has described a clinical condition characterized by both gain and loss of Gsα function, due to a heterozygous de novo variant of the maternal GNAS allele. PATIENTS AND METHODS We describe a girl with a complex combination of clinical signs and a new heterozygous GNAS variant. For the molecular analysis of GNAS gene, DNA samples of the proband and her parents were extracted from their peripheral blood samples. In silico analysis was performed to predict the possible in vivo effect of the detected novel genetic variant. The activity of Gsα protein was in vitro analyzed from samples of erythrocyte membranes, recovered from heparinized blood samples. RESULTS We found a new heterozygous missense c.166A > T-(p.Ile56Phe) GNAS variant in exon 2, inherited from the mother that determined a reduced activity of 50% of Gsα protein function. The analysis of her parents showed a 20-25% reduction in Gsα protein activity in the mother and a normal function in the father. Clinically our patient presented a multisystemic disorder characterized by hyponatremia compatible with a nephrogenic syndrome of inappropriate antidiuresis, subclinical hyperthyroidism, subclinical hypercortisolism, precocious thelarche and pubarche and congenital bone abnormalities. CONCLUSIONS This is the first time that the new variant c.166A > T (p.Ile56Phe) on exon 2 of GNAS gene, originated on maternal allele, has been described as probable cause of a multisystemic disorder. Although the mutation is associated with a reduced activity of the function of Gsα protein, this unusual phenotype on the contrary suggests a mild functional gain.
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Affiliation(s)
- Cavarzere Paolo
- Pediatric Division, Department of Pediatrics, University Hospital of Verona, Piazzale Stefani 1, 37126, Verona, Italy.
| | - Gastaldi Andrea
- Pediatric Division, Department of Pediatrics, University Hospital of Verona, Piazzale Stefani 1, 37126, Verona, Italy
| | - Francesca Marta Elli
- Endocrinology Unit, Department of Clinical Sciences and Community Health, University of Milan, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Gaudino Rossella
- Pediatric Division, Department of Pediatrics, University Hospital of Verona, Piazzale Stefani 1, 37126, Verona, Italy.,Pediatric Clinic, Department Surgical Sciences, Dentistry, Gynecology and Pediatrics, University of Verona, Verona, Italy
| | - Peverelli Erika
- Endocrinology Unit, Department of Clinical Sciences and Community Health, University of Milan, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Brugnara Milena
- Pediatric Division, Department of Pediatrics, University Hospital of Verona, Piazzale Stefani 1, 37126, Verona, Italy
| | - Susanne Thiele
- Division of Paediatric Endocrinology and Diabetes, Department of Pediatrics, University of Lübeck, Luebeck, Germany
| | - Granata Francesca
- General Medicine Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Mantovani Giovanna
- Endocrinology Unit, Department of Clinical Sciences and Community Health, University of Milan, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
| | - Antoniazzi Franco
- Pediatric Division, Department of Pediatrics, University Hospital of Verona, Piazzale Stefani 1, 37126, Verona, Italy.,Pediatric Clinic, Department Surgical Sciences, Dentistry, Gynecology and Pediatrics, University of Verona, Verona, Italy.,Regional Center for the Diagnosis and Treatment of Children and Adolescents Rare Skeletal Disorders. Pediatric Clinic, Department of Surgical Sciences, Dentistry, Gynecology and Pediatrics, University of Verona, Verona, Italy
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Potential Use of Pharmacogenetics to Reduce Drug-Induced Syndrome of Inappropriate Antidiuretic Hormone (SIADH). J Pers Med 2021; 11:jpm11090853. [PMID: 34575630 PMCID: PMC8466173 DOI: 10.3390/jpm11090853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 08/25/2021] [Accepted: 08/26/2021] [Indexed: 11/21/2022] Open
Abstract
Syndrome of inappropriate antidiuretic hormone (SIADH) is a common cause of hyponatremia, and many cases represent adverse reactions to drugs that alter ion channel conductance within the peptidergic nerve terminals of the posterior pituitary. The frequency of drug-induced SIADH increases with age; as many as 20% of patients residing in nursing homes have serum sodium levels below 135 mEq/L. Mild hyponatremia is associated with cognitive changes, gait instability, and falls. Severe hyponatremia is associated with cerebral edema, seizures, permanent disability, and/or death. Although pharmacogenetic tests are now being deployed for some drugs capable of causing SIADH (e.g., antidepressants, antipsychotics, and opioid analgesics), the implementation of these tests has been based upon the prior known association of these drugs with other serious adverse drug reactions (e.g., electrocardiographic abnormalities). Work is needed in large observational cohorts to quantify the strength of association between pharmacogene variants and drug-induced SIADH so that decision support can be developed to identify patients at high risk.
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