Evaluation of a new DNA test compared with the lactose hydrogen breath test for the diagnosis of lactase non-persistence

Högenauer, Christoph; Hammer, Heinz F.; Mellitzer, Karin; Renner, Wilfried; Krejs, G. J.; Toplak, Hermann

doi:10.1097/00042737-200503000-00018

Cited by 82 publications

(69 citation statements)

References 12 publications

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“…Recent studies have demonstrated a 91-97% agreement of CC genotype with positive HBT results, and an 86-95% agreement between CT and TT genotypes and negative HBT results (5,7). Mutation analysis for the diagnosis of lactose malabsorption related to HBT presented a 97% positive and an 86% negative predictive value (7).…”

Section: Discussionmentioning

confidence: 99%

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Correlation between lactose absorption and the C/T-13910 and G/A-22018 mutations of the lactase-phlorizin hydrolase (LCT) gene in adult-type hypolactasia

Bulhões

Goldani

Oliveira

et al. 2007

Braz J Med Biol Res

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The C/T-13910 mutation is the major factor responsible for the persistence of the lactase-phlorizin hydrolase (LCT ) gene expression. Mutation G/A-22018 appears to be only in co-segregation with C/T-13910. The objective of the present study was to assess the presence of these two mutations in Brazilian individuals with and without lactose malabsorption diagnosed by the hydrogen breath test (HBT). Ten milk-tolerant and 10 milk-intolerant individuals underwent the HBT after oral ingestion of 50 g lactose (equivalent to 1 L of milk). Analyses for C/T-13910 and G/A-22018 mutations were performed using a PCR-based method. Primers were designed for this study based on the GenBank sequence. The CT/GA, CT/AA, and TT/AA genotypes (lactase persistence) were found in 10 individuals with negative HBT. The CC/GG genotype (lactase non-persistence) was found in 10 individuals, 9 of them with positive HBT results. There was a significant agreement between the presence of mutations in the LCT gene promoter and HBT results (kappa = -0.9, P < 0.001). The CT/AA genotype has not been described previously and seems to be related to lactase persistence. The present study showed a significant agreement between the occurrence of mutations G/A-22018 and C/T-13910 and lactose absorption in Brazilian subjects, suggesting that the molecular test used here could be proposed for the laboratory diagnosis of adult-type primary hypolactasia. Correspondence

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Section: Discussionmentioning

confidence: 99%

“…Nevertheless, it can cause symptoms such as bloating, vomiting, abdominal distension, abdominal pain, and diarrhea in intolerant patients. Sensitivity ranges from 69 to 100% and specificity from 96 to 100% when compared to lactase activity measurement in the intestinal biopsy (3,6,7).…”

Section: Introductionmentioning

confidence: 99%

Correlation between lactose absorption and the C/T-13910 and G/A-22018 mutations of the lactase-phlorizin hydrolase (LCT) gene in adult-type hypolactasia

Bulhões

Goldani

Oliveira

et al. 2007

Braz J Med Biol Res

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“…This can be an interesting advantage over enzyme activity data obtained from biopsy specimens, usually taken from the proximal small intestine, where lactase is low (30, 31 ), in addition to the possible uneven expression of the enzyme (1,32 ). Single-nucleotide polymorphisms upstream from the lactase gene have been associated with adult-type hypolactasia (33,34 ) and tested to identify individuals with genetic disposition for this disorder (35,36 ). A functional test of lactase activity is essential, however, for proper assessment of patient situation because both residual enzyme activity and clinical symptoms can vary within an ample range, and low lactase activity can have other causes.…”

Section: Discussionmentioning

confidence: 99%

Noninvasive Evaluation of Intestinal Lactase with 4-Galactosylxylose: Comparison with 3- and 2-Galactosylxylose and Optimization of the Method in Rats

et al. 2006

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Background: Urinary excretion of D-xylose by suckling rats after ingestion of a mixture of 4-, 3-, and 2-galactosylxyloses reflects lactase activity in vivo. We aimed to select the most convenient of these disaccharides for detecting changes of the enzyme activity in vivo and to optimize the method. Methods: 4-, 3-, and 2-Galactosylxyloses were synthesized and purified, then orally administered to suckling rats of different ages. D-Xylose was measured colorimetrically by the phloroglucinol reaction in urine and plasma. Lactase activity was determined in extracts of small intestine mucosa with lactose, galactosylxyloses, and phlorizin as substrates. Results: D-Xylose appeared in the urine in a dosedependent manner after ingestion of any of the 3 galactosylxylose disaccharides. Correlation between D-xylose elimination and intestinal lactase activity was highest with 4-galactosylxylose (r ‫؍‬ 0.97; n ‫؍‬ 24), lower with 2-galactosylxylose (r ‫؍‬ 0.89; n ‫؍‬ 24), and lowest with 3-galactosylxylose (r ‫؍‬ 0.34; n ‫؍‬ 23). The kinetic properties of intestinal lactase accounted for these differences. D-Xylose concentration in plasma after administration of 4-galactosylxylose also correlated with lactase activity (r ‫؍‬ 0.93; n ‫؍‬ 33).

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“…Az ausztriai Grazban 153 betegben a CC genotípus aránya 24,1% volt [19], Lengyelországban 58 eset 26%-a [20], egy másik tanulmányban 38% [21], egy másik ausztriai dolgozatban 263 beteg 19,4%-a [22]. Az ará-nyok különbségeiben szerepe van a lakosság származási hátterének és az etnikumok keveredésének.…”

Section: Megbeszélésunclassified

Laktózintolerancia: a laktázgén C/T-13910 polimorfizmusának és a hidrogénkilégzési teszt pontosságának retrospektív kiértékelése gasztroenterológiai szakrendelésen

2016

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Bevezetés: A felnőtt típusú hypolactasia a leggyakoribb szénhidrát-felszívódási zavar. Célkitűzés: A laktázgén C/T-13910-polimorfizmus eloszlásának és a H 2 -kilégzési teszt pontosságának, valamint a genetikai és kilégzési teszt konkordanciájának kiértékelése. Módszer: A retrospektív tanulmányba 496, tejcukor-érzékenység tüneteivel jelentkező beteget válogattak be. A szerzők a C/T-13910 genotípust TaqMan polimeráz láncreakcióval, a laktózintoleranciát H 2 -kilégzési teszttel vizsgálták. Eredmények: A C/T-19310 genotípusok eloszlása az alábbi volt: CC: 48,1%, TC: 40,5%, TT: 11,4%. A genetikai tesztet viszonyítási alapnak véve, a kilégzési teszt érzékenysége 84,3%, fajlagossága 95,7%, pozitív prediktív értéke 96,7%, negatív prediktív értéke 80,4% volt. A kilégzési tesztet viszonyítási alapul véve, a genetikai teszt érzékenysége 96,6%, fajlagossága 80,4%, pozitív prediktív értéke 84,3%, negatív prediktív értéke 95,7% volt. A két vizsgálat konkordanciája (kappa-index) 0,78 volt. Az esetek 11,1%-ában volt a két vizsgálat eredménye diszkordáns. Következtetések: Laktózérzékenység panaszaival jelentkező betegekben a hypolactasiára jellemző CC genotípus az esetek majdnem felében kimutatható. A genetikai és kilégzési teszt pontossága hasonló, mindkettő használható a diagnózis alapjául, egymást kiegészítik. A két teszt konkordanciája jó. A diszkordáns esetekben a jelenség okát meg kell keresni. Orv. Hetil., 2016, 157(25), 1007-1112.Kulcsszavak: genetikai teszt, hidrogénkilégzési teszt, hypolactasia, laktózintolerancia, polimorfizmus Accuracy of lactase gene C/T-13910 polymorphism and hydrogen breath test in a gastroenterology outpatient clinic: a retrospective studyIntroduction: Adult type hypolactasia is the most prevalent carbohydrate malabsorption. Aim: To assess the distribution of lactase gene C/T-13910 polymorphism and the accuracy and concordance of a genetic test and H 2 breath test in the diagnosis of adult type hypolactasia. Method: 496 patients with symptoms of lactose intolerance were enrolled in a retrospective study who underwent genetic test using TaqMan polymerase chain reaction and H 2 breath test. Results: The prevalence of C/T-13910 genotypes was: CC 48.1%, TC: 40.5%, and TT: 11.4%. When the genetic test was taken as reference, the sensitivity of the breath test was 84.3%, with a specificity of 95.7%, a positive predictive value of 96.7% and negative predictive value of 80.4%. Conversely, the accuracy of genetic test was: sensitivity 96.6%, specificity 80.4%, positive predictive value 84.3% and negative predictive value 95.7%. The concordance value between the two tests (kappa index) was 0.78. The results were discordant in 11.1% of the cases. Conclusions: In symptomatic patients, the lactase non-persistence genotype CC occurred in almost half of the patients. Both the genetic and the breath tests are sufficiently accurate, with good predictive value and they can be used to set up the diagnosis. Discordant results should be carefully interpreted.

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Evaluation of a new DNA test compared with the lactose hydrogen breath test for the diagnosis of lactase non-persistence

Cited by 82 publications

References 12 publications

Correlation between lactose absorption and the C/T-13910 and G/A-22018 mutations of the lactase-phlorizin hydrolase (LCT) gene in adult-type hypolactasia

Correlation between lactose absorption and the C/T-13910 and G/A-22018 mutations of the lactase-phlorizin hydrolase (LCT) gene in adult-type hypolactasia

Noninvasive Evaluation of Intestinal Lactase with 4-Galactosylxylose: Comparison with 3- and 2-Galactosylxylose and Optimization of the Method in Rats

Laktózintolerancia: a laktázgén C/T-13910 polimorfizmusának és a hidrogénkilégzési teszt pontosságának retrospektív kiértékelése gasztroenterológiai szakrendelésen

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