Seppo Leena, Tuure Tuula, Korpela Riitta, Järvelä Irma, Rasinperä Heli, Sahi Timo
Valio Ltd., Helsinki, Finland.
Scand J Gastroenterol. 2008;43(9):1082-7. doi: 10.1080/00365520802095485.
The age at manifestation of primary hypolactasia varies between ethnic groups. Many people report experiencing the first symptoms of lactose intolerance at adult age. The purpose of this study was to investigate whether primary hypolactasia can appear after the age of 20 among the Finnish population and to investigate the outcome of different diagnostic methods of lactose maldigestion.
Lactose digestion status was assessed by the lactose tolerance test with ethanol (LTTE) in 42 subjects (38-71 years) who reported having gastrointestinal symptoms after the ingestion of 20 g or less of lactose and who were diagnosed as lactose digesters in earlier studies. Thirteen of the study subjects underwent upper gastrointestinal endoscopy, and 35 gave a blood sample for DNA analysis.
Only one of the 42 subjects studied had the genotype C/C(-13910) indicating hypolactasia. Lactase activity was higher in those with the genotype T/T (69.2 U/g protein) than in those with the heterozygous genotype C/T (36.3 U/g protein) (p=0.017).
Although primary hypolactasia normally appears before the age of 20 years, the decline in lactase activity may on rare occasions continue after that age. Genotyping of the C/T(-13910) variant was found to be a reliable diagnostic approach in defining the lactase persistence/non-persistence status of the study subjects.
原发性乳糖酶缺乏症出现的年龄在不同种族群体中有所差异。许多人报告称在成年后才出现乳糖不耐受的最初症状。本研究的目的是调查在芬兰人群中，原发性乳糖酶缺乏症是否会在20岁以后出现，并研究乳糖消化不良不同诊断方法的结果。
对42名受试者（年龄38 - 71岁）进行了乙醇乳糖耐受试验（LTTE）以评估乳糖消化状态，这些受试者在摄入20克或更少乳糖后报告有胃肠道症状，且在早期研究中被诊断为乳糖消化者。13名研究对象接受了上消化道内镜检查，35名提供了血样用于DNA分析。
在42名研究对象中，只有1人具有表明乳糖酶缺乏的基因型C/C(-13910)。基因型为T/T的个体乳糖酶活性（69.2 U/g蛋白）高于杂合基因型C/T的个体（36.3 U/g蛋白）（p = 0.017）。
虽然原发性乳糖酶缺乏症通常在20岁之前出现，但在极少数情况下，乳糖酶活性在该年龄之后仍可能继续下降。发现对C/T(-13910)变体进行基因分型是确定研究对象乳糖酶持续存在/不存在状态的可靠诊断方法。
