Büning Carsten, Genschel Janine, Jurga Juliane, Fiedler Thomas, Voderholzer Winfried, Fiedler Eva-Maria, Worm Margitta, Weltrich Renita, Lochs Herbert, Schmidt Hartmut, Ockenga Johann
Department of Gastroenterology, Hepatology and Endocrinology, Charité, Campus Mitte, Humboldt University of Berlin, Berlin, Germany.
Digestion. 2005;71(4):245-50. doi: 10.1159/000087050. Epub 2005 Jul 12.
To evaluate genotyping for two DNA variants (c.1993+327C>T and c.1438+117G>A), recently found to be associated with adult-type hypolactasia, in the diagnosis of lactose intolerance.
In total, 166 consecutive patients with gastrointestinal symptoms mimicking hypolactasia admitted to the clinic between March 2002 and December 2002 were included. Genotyping for the two DNA variants (c.1993+327C>T and c.1438+117G>A) and standard H2 breath test was performed.
Among 116 patients with positive H2 breath test, the c.1993+327C variant was detectable in 106 (91.4%) patients. Among 50 patients with negative H2 breath test, the c.1993+327C variant was seen in 2 patients. Sensitivity, specificity, positive and negative predictive values for the c.1993+327C variant were 91.4, 96.0, 98.1 and 82.8%, respectively. Genotyping for the c.1438+117G variant did not bring any additional information. Among 4 of the 10 patients with positive H2 breath test but negative for the c.1993+327C and the c.1438+117G variant,further evaluation revealed other diseases known to cause secondary hypolactasia such as celiac disease and short bowel syndrome.
In symptomatic patients, genotyping for the DNA variant c.1993+327C is a reliable test for adult-type hypolactasia with high sensitivity and specificity and thus provides a new tool in the diagnostic workup of hypolactasia.
评估两种DNA变异（c.1993+327C>T和c.1438+117G>A）的基因分型在乳糖不耐受诊断中的作用，这两种变异最近被发现与成人型低乳糖酶症相关。
纳入2002年3月至2002年12月期间连续收治的166例有类似低乳糖酶症胃肠道症状的患者。对两种DNA变异（c.1993+327C>T和c.1438+117G>A）进行基因分型，并进行标准的H2呼气试验。
在116例H2呼气试验阳性的患者中，106例（91.4%）可检测到c.1993+327C变异。在50例H2呼气试验阴性的患者中，2例出现c.1993+327C变异。c.1993+327C变异的敏感性、特异性、阳性预测值和阴性预测值分别为91.4%、96.0%、98.1%和82.8%。c.1438+117G变异的基因分型未提供任何额外信息。在10例H2呼气试验阳性但c.1993+327C和c.1438+117G变异阴性的患者中，有4例进一步评估发现了其他已知可导致继发性低乳糖酶症的疾病，如乳糜泻和短肠综合征。
对于有症状的患者，c.1993+327C DNA变异的基因分型是诊断成人型低乳糖酶症的可靠检测方法，具有高敏感性和特异性，因此为低乳糖酶症的诊断检查提供了一种新工具。
