Association of ulcerative colitis with rare VNTR alleles of the human intestinal mucin gene, MUC3

Abstract

Ulcerative colitis (UC), a common form of inflammatory bowel disease, is a multifactorial disorder with significant genetic influence. Recently, evidence of linkage on chromosome 7q near the intestinal mucin gene MUC3 was reported by an affected sib-pair analysis. Previous reports indicate a possible mucin abnormality in UC patients, but whether genetic differences in a specific mucin gene are associated with UC is unknown. Here we analysed polymorphisms of variable number of tandem repeats (VNTRs) within this gene using DNAs obtained from 243 Japanese (75 patients with UC and 168 controls), and to confirm the result we undertook a two-stage examination using 328 Caucasian samples (72 and 85 with UC in the first and second stages, respectively, and 171 controls). When the frequency of patients carrying one or two rare VNTR alleles was compared with that of controls, a significant increase was found first in Japanese patients (odds ratio 2.72, 95% CI 1.17-6.32, P = 0. 0308). In Caucasians, the odds ratio was 2.80 (95% CI 1.36-5.75, P = 0.0079) in the first stage, 2.43 (95% CI 1.20-4.92, P = 0.0196) in the second stage and 2.60 (95% CI 1.41-4.80, P = 0.0024) in total. The overall odds ratio was 2.64 (95% CI 1.60-4.33, P = 0.0001). This result suggests that rare alleles of the MUC3 gene may confer genetic predisposition to UC.

Associations of distinct variants of the intestinal mucin gene MUC3A with ulcerative colitis and Crohn's disease

“…We could not explain the dominant effect observed in the association study we reported recently (Kyo et al 1999), because human MUC3 was considered to be a secretory mucin and mucin protein encoded by a common allele would compensate for the function of that encoded by a rare allele. Furthermore, it has been unknown whether the 51-bp repetitive regions lie in a single gene, making an internal duplication, or whether they lie in two tandemly arrayed genes (Gum et al 1997).…”

“…Five micrograms of genomic DNA were digested to completion with restriction enzyme Pvull (Toyobo, Tokyo, Japan), run in 0.5% agarose gel (13 cm long) at 25 V for 48 h and transferred to a nylon membrane, as described previously (Kyo et al 1999). Blots were proved with a clone composed of a 51-bp repeat (51R), a 498-bp clone corresponding to a part of 1125-bp repeat unit located between Pvull-restriction site and 51-bp repeat (1125D), a 796-bp clone corresponding to a semi-unique region located between the 177-bp repeat and the 51-bp repeat (SUR), or three distinct parts of the 3Ј region of "MUC3", the sequence of which Gum et al (1997) reported previously (3TR-1, 3TR-2, or 3TR-3; Fig.…”

“…1b). Clone 51R was prepared as described (Kyo et al 1999), and clone 1125D was prepared by PCR amplification, using primers 1125DF and 1125DR (Table 1); the PCR reaction consisted of one cycle of denaturation at 95°C for 5 min, 35 cycles of denaturation at 94°C for 30 s, annealing at 57°C for 30 s, and extension at 72°C for 30 s. Clone SUR was also prepared likewise, using primers SUR-F and SUR-R (Table 1); the PCR regime included one cycle of 95°C for 5 min, 35 cycles of 94°C for 30 s, 57°C for 30 s, and 72°C for 1 min. Clones 3TR-1 to -3 were prepared by PCR, using primer sets 3TR-1F/3TR-1R, 3TR-2F/3TR-2R, and 3TR-3F/3TR-3R (Table 1), respectively, which were constructed on the basis of the reported sequence (Gum et al 1997); the PCR regime included one cycle of 95°C for 5 min, 35 cycles of 94°C for 30s, 57°C for 30 s for 3TR-1 and 3TR-3 (55°C for 30 s for 3TR-2), and 72°C for 1 min for 3TR-1 (for 30 s for 3TR-2 and 3TR-3).…”

“…These clones were confirmed by sequencing and were labeled by the random priming method, using a Megaprime DNA labeling system (Amersham, Buckinghamshire, UK) according to the manufacturer's instructions. The hybridization and washing of the blots were carried out as described (Kyo et al 1999). …”

“…The fact that the marker D7S669 is located near the human intestinal mucin gene "MUC3" and previous reports that indicated a possible mucin abnormality in IBD patients (Buisine et al 1999;Tysk et al 1991) prompted us to examine a correlation between "MUC3" and IBDs. Genotying of variable number of tandem repeat (VNTR) in the "MUC3" gene implied that rare alleles of "MUC3", which have an unusual number of 51-bp repeat units, are associated with the risk of UC (Kyo et al 1999).…”