Mutations and down-regulation of CDX1 in children with anorectal malformations

Abstract

Background: Anorectal malformations (ARMs) represent a variety of congenital disorders that involve abnormal termination of the anorectum. This study was to reveal relation between CDX1 and human ARMs phenotypes.

Methods: 108 Chinese patients and 120 Chinese controls were included in this study. We analyzed the relation between two by PCR, qRT-PCR, western blot and immunofluorescence.

Results: Four heterozygous mutations in CDX1 gene were identified in ARMs patients (3.7%, 4/108), no found in controls. CDX1 protein expression was significantly decreased in the ARMs compared with the control anorectum. All samples analyzed in ARMs group exhibited down-regulated CDX1 mRNA expression in comparison to matched normal group, demonstrated significant differences statistically.

Conclusion: The findings represented the relation between CDX1 mutations and CDX1 genotype. Furthermore, it was suggested that the downregulation of CDX1 might be related to the development of ARMs.

Keywords: Anorectal malformations; CDX1; children; mutation.

Figure 1

CDX1 exons mutation in ARMs patients. Sequence electropherograms documenting the c.213-214Ins GAA mutation (arrow) found in exon 1 of CDX1 gene, the c.6G>C, c.27G>T, c.18A>C mutation (*) found in exon 3 of CDX1 gene.

Figure 2

Expression of CDX1 and Tcf4 of control and high-type ARMs, as revealed by immunofluorescence staining. Positive immunolabelling was detected as green for CDX1 protein in the histiocytic cytoplasm of the epithelium of the rectum and in the nuclei of intestinal villus in the control. Expression of CDX1 was weaker in the high-type ARMs patients than in the control group. A (CDX1), B (Tcf4), C (Merged): control; a (CDX1), b (Tcf4), c (Merged): ARMs.(original magnification×400).

Figure 3

Representative Western blots showing CDX1 protein expression within the rectum of control and ARMs. β-Actin was used to confirm equal protein loading and transfer. Obvious differences in CDX1 protein expression between control and ARMs groups were found. *P<0.05 vs. the control.

Figure 4

Representative Quantitative real-time RT-PCR shown CDX1 mRNA expression within the rectum of control and ARMs. Obvious differences in CDX1 mRNA expression between control and ARMs groups were found. *P<0.05 vs. the control.