警惕新生儿先天性乳糖酶缺乏

Vigilance Congenital Lactase Deficiency of Newborns

先天性乳糖酶缺乏(congenital lactase deficiency,CLD)是一种非常罕见终身性疾病属于常染色体隐性遗传病,始发于新生儿期,以第一次接触母乳后发生严重腹泻并伴有生长缓慢为主要特征,给婴幼儿生长发育带来严重的不良影响。经过国内外学者多年的研究发现其流行病率远比想象中的要高。因此,在临床工作中应警惕CLD的发生。CLD与原发性乳糖酶缺乏即成人型乳糖酶缺乏(adult-type hypolactasia,ATH)一样均属于常染色体隐性遗传,决定乳糖酶(lactase,LCT)的基因位于2q21染色体上,但它们的分子生物学机制却不同。CLD主要通过介导无意义的LCT基因的m RNA降解完成,ATH主要通过增强子多态性在LCT基因转录水平调节肠道细胞的乳糖酶合成。乳糖酶缺乏的实验室检测方法有很多,但目前对于新生儿CLD的检测方法较为实用的有基因检测及尿半乳糖酶试剂盒检测。目前较好的治疗方法是乳糖酶治疗。虽然目前为止我国未报道过一例CLD,但2012年日本已发现的2个CLD案例。因此我们应对该隐性遗传病提高应有的警惕性,并重视对其分子生物学机制进一步研究,以防患于未然,同时也有助于指导CLD患者的基因治疗。

Congenital lactase deficiency （CLD） is a lifelong disease which is the rare autosomal recessive genetic disease, originating in the neonatal period, with the first contact of breast milk and accompanied by severe diarrhea that may have the serious adverse effects on the growth of infants with main characteristics. Several researches have found that the epidemic rate is much higher than expected. Thus, the clinical work should be alert to the occurrence of CLD. CLD is a kind of autosomal recessive such as the ATH, which is different from the decided lactase （LCT） gene that located on chromosome 2q21 in terms of the molecular biological mechanisms. CLD is mainly mediated by mRNA degradation meaningless of LCT, while ATH is mainly composed by means of enhancing the transcription regulation of intestinal cells that synthesizing lactase promoter polymorphism in the LCT gene. There are many laboratory methods to detect the lactase deficiency. The mainly used methods for the detection of neonatal CLD are the genetic testing and the urine galactosidase detection. The lactase treatment is preferably in the recent years. It is reported that two cases with CLD were confirmed in Japan, but no one was found in China. Therefore, we should pay attention to explore the molecular biological mechanism of CLD in order to guide the gene therapy for patients.