Studies on the expression of intestinal lactase in different individuals.

Abstract

Sixty one duodenal biopsy specimens were examined for the expression of lactase at the level of enzyme activity, protein, and messenger RNA. Of the 51 samples with normal villous architecture, 39 were lactase persistent, 11 were nonpersistent (adult type hypolactasia), and one was of indeterminate status. All the lactase persistent individuals showed high mRNA and a high level of the lactase protein as detected by sodium dodecyl sulphate polyacrylamide gel electrophoresis. All the 11 non-persistent individuals tested showed a low level of lactase protein.Nine of the 10 samples tested showed low mRNA and one high mRNA. These results suggest that the lactase persistence polymorphism is controlled at the level of the expression of the lactase gene, though there may be some heterogeneity of the lactase non-persistence phenotype. (Gut 1995; 36: 28-33)

Expression of Human Intestinal mRNA Transcripts during Development: Analysis by a Semiquantitative RNA Polymerase Chain Reaction Method

“…4 lanes 5-8). The results of our analysis of the nonpersistent adults will be reported elsewhere (39). Lactase mRNA was present at much lower levels in all the fetal small intestine samples (Fig.…”

“…This is consistent with the fact that marked differences have been noted in other species (1) and also with the fact that there appears to be very little similarity between the two promoters (36,48,49). The RNA PCR method described here is proving invaluable for the analysis of the expression of these enzymes in biopsy specimens taken from lactase-persistent and -nonpersistent adults (39) and from children with malabsorption and should be useful to other investigators studying gene expression.…”

The Causal Element for the Lactase Persistence/ non‐persistence Polymorphism is Located in a 1 Mb Region of Linkage Disequilibrium in Europeans

“…The results were assessed in relation to lactase persistence status as well as S/L ratio. The -14 kbT allele and the -22 kbA allele were found in one or two copies in all the persistent individuals (31/36 of whom were of UK ancestry), and were not present in any of the non-persistent individuals nor in the one person for whom the diagnosis was ambiguous (Table 2) (all but one of non-UK ancestry) (Harvey et al 1995b;. All non-A haplotype chromosomes carried a C at − 14 kb and a G at -22 kb, and all -14 kbT alleles and -22 kbA alleles were associated with A haplotype chromosomes.…”

“…However, comparison of the CT -14 kb and GA -22 kb results with the previously determined trimodal distribution of enzyme activity ratios gave an unexpected distribution. If the T allele is truly causal of high lactase expression in adult life, it would be expected that Figure 5 Histogram showing the CT -14 kb genotypes superimposed on the activity distribution, expressed as sucrase/lactase ratio (S/L) as reported before (Harvey et al 1995b). Two CT samples shown cross-hatched are those for which there was discordance between the -14 kb result and the -22 kb result.…”

Characterisation of a human homologue of a yeast cell division cycle gene, MCM6, located adjacent to the 5′ end of the lactase gene on chromosome 2q21

“…The human tissues were as described previously [1,[15][16][17]. Semiquantitative RT-PCR was performed using the method described previously [15] except that the RT was performed at 37°C using 1 Ixg total RNA as starting material for 10 PCR reactions and, for MCM6 only, 30 rounds of amplification (which gave a linear dose response for this transcript).…”