多数哺乳动物在断奶后乳糖酶活性下降,但在人类的某些种族(如北欧)中,乳糖酶活性在成人期可持续存在。目前认为,对决定高或低的乳糖酶mRNA表达的乳糖酶持续或非持续的多形性遗传差异性应答表现在乳糖酶基因方面。为了解儿童及胎儿中与年龄有关的乳糖酶表达,对年龄在1～203个月儿童的小肠活检标本作酶活性的回顾性分析并应用PCR法及半定量RT-PCR法作RNA前瞻性分析。 (1)组织学正常的小肠活检标本乳糖酶活性的回顾性研究 Most mammals have decreased lactase activity after weaning, but lactase activity persists in adulthood in some human populations (eg Northern Europe). It is currently believed that the persistent or non-persistent polymorphic genetic response to lactase that determines high or low lactase mRNA expression is manifested in the lactase gene. To understand the age-related expression of lactase in children and fetuses, a retrospective analysis of the enzymatic activity of small intestinal biopsies from children aged 1 to 203 months was performed and prospectively analyzed by PCR and semi-quantitative RT-PCR . (1) Retrospective study of lactase activity in histologically normal small intestinal biopsy specimens