Connexin 30 (GJB6) deletion as a cause of a false positive sweat test result.
Por:
Rossell A, Soler-García a, Martorell-Sampol L, Clavería MA, Valero L, Rodríguez S, Badenas C and Cols M
Publicada:
12 jun 2025
Ahead of Print:
12 jun 2025
Resumen:
The sweat test (ST) is the gold standard for the diagnosis of cystic fibrosis. There are several reports in the literature regarding conditions that are known to be associated with a false positive result. The aim of this article is to describe a previously unreported cause of a false positive ST. An observational, cross-sectional single-center study was performed. We recruited three patients with a neurosensory deafness caused by a deletion in both alleles of connexin 30. The first-degree relatives of these three patients with hearing impairment due to other mutations were also included. A ST was performed in all the selected cases. Among the three patients with a deletion in both connexin 30 alleles, two had a positive ST, whereas the third patient had a close-to-positivity borderline result (57 mmol/L). Moreover, there were no positive sweat tests in individuals with other mutation patterns. CONCLUSION: Patients with affection of both alleles of connexin 30 were the only ones to show a positive ST, which may translate to a higher risk of hyponatremic dehydration. The reason for the ST positivity remains unclear and may be related to the fact that connexin 30 plays a role in modulating other molecules in both the inner ear and sweat glands. WHAT IS KNOWN: • The sweat test is the gold standard for the diagnosis of cystic fibrosis. However, the causes of false positives in the test are increasingly recognized. WHAT IS NEW: • This study describes a previously unreported cause of a false positive sweat test. Three patients with homozygous mutations in the connexin 30 gene are described. All of them had an abnormal sweat test, and two of them presented with severe hyponatremic dehydration.
Filiaciones:
Rossell A:
Pediatrics Department, Hospital Sant Joan de Déu, Passeig de Sant Joan de Déu 2, 08950, Esplugues de LlobregatBarcelona, Spain
Soler-García a:
Pediatrics Department, Hospital Sant Joan de Déu, Passeig de Sant Joan de Déu 2, 08950, Esplugues de LlobregatBarcelona, Spain
Infectious Diseases and Microbiome Research Group, Institut de Recerca Sant Joan de Déu, Barcelona, Spain
Departament de Cirurgia i Especialitats Medicoquirúrgiques, Facultat de Medicina i Ciències de la Salut, Universitat de Barcelona, Barcelona, Spain
Martorell-Sampol L:
Department of Genetic and Molecular Medicine, Hospital Sant Joan de Déu, Barcelona, Spain
Clavería MA:
Department of Pediatric Otorhinolaryngology, Hospital Sant Joan de Déu, Barcelona, Spain
Valero L:
Pediatrics Department, Hospital Sant Joan de Déu, Passeig de Sant Joan de Déu 2, 08950, Esplugues de LlobregatBarcelona, Spain
Rodríguez S:
Pediatric Pulmonology Department and Cystic Fibrosis Unit, Hospital Sant Joan de Déu, Barcelona, Spain
Badenas C:
Biochemistry and Molecular Genetics Department, Hospital Clínic de Barcelona, IDIBAPS, University of Barcelona, Barcelona, Spain
Centro de Investigación Biomédica en Red en Enfermedades Raras, Instituto de Salud Carlos III, Barcelona, Spain
Cols M:
Pediatric Pulmonology Department and Cystic Fibrosis Unit, Hospital Sant Joan de Déu, Barcelona, Spain
Hosp St Joan Deu, Pediat Dept, Passeig St Joan de Deu 2, Barcelona
08950, Spain
Inst Recerca St Joan de Deu, Infect Dis & Microbiome Res Grp, Barcelona,
Spain
Univ Barcelona, Dept Cirurgia & Especialitats Med quirurg, Fac Med &
Ciencies Salut, Barcelona, Spain
Hosp St Joan de Deu, Dept Genet & Mol Med, Barcelona, Spain
Hosp St Joan de Deu, Dept Pediat Otorhinolaryngol, Barcelona, Spain
Hosp St Joan de Deu, Pediat Pulmonol Dept, Barcelona, Spain
Hosp St Joan Deu, Cyst Fibrosis Unit, Barcelona, Spain
Univ Barcelona, Hosp Clin Barcelona, IDIBAPS, Dept Biochem & Mol Genet,
Barcelona, Spain
Inst Salud Carlos III, Ctr Invest Biomed Red Enfermedades Raras,
Green Submitted, hybrid
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