Rossell Anna, Soler-Garcia Aleix, Martorell Loreto, Claveria Maria Antònia, Valero Laura, Rodríguez Sílvia, Badenas Cèlia, Cols-Roig Maria
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.
Eur J Pediatr. 2025 Jun 12;184(7):416. doi: 10.1007/s00431-025-06220-7.
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.
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.
• 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.
• 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.
汗液试验（ST）是诊断囊性纤维化的金标准。文献中有几篇报道了已知与假阳性结果相关的情况。本文的目的是描述一种先前未报道的汗液试验假阳性原因。进行了一项观察性横断面单中心研究。我们招募了3名因连接蛋白30两个等位基因缺失而导致神经感觉性耳聋的患者。这3名因其他突变导致听力障碍的患者的一级亲属也被纳入研究。对所有选定病例进行了汗液试验。在连接蛋白30两个等位基因均缺失的3名患者中，2名汗液试验呈阳性，而第3名患者的结果接近阳性临界值（57 mmol/L）。此外，其他突变模式的个体汗液试验均未呈阳性。
连接蛋白30两个等位基因均受影响的患者是唯一汗液试验呈阳性的患者，这可能意味着低钠血症性脱水风险更高。汗液试验呈阳性的原因尚不清楚，可能与连接蛋白30在内耳和汗腺中调节其他分子的作用有关。
• 汗液试验是诊断囊性纤维化的金标准。然而，该试验假阳性的原因越来越受到认可。
• 本研究描述了一种先前未报道的汗液试验假阳性原因。描述了3名连接蛋白30基因纯合突变的患者。他们所有人的汗液试验均异常，其中2人出现严重的低钠血症性脱水。
