The Expression Analysis of Notch-1 and Jagged-2 During the Development of the Hindgut in Rat Embryos with Ethylenethiourea Induced Anorectal Malformations

Spatiotemporal expression of neurogenic locus notch homolog protein 1 in developing caudal spinal cord of fetuses with anorectal malformations from ETU-fed rats

Complications, such as fecal soiling, incontinence, and constipation, are major health issues for patients with anorectal malformations (ARMs) after surgery. Dysplasia of the caudal spinal cord is an increasingly pivotal area in the field of postoperative complications for patients with ARMs. However, the existing research has not fully defined the mechanism underlying ARMs development. The neurogenic locus notch homolog (Notch) signaling pathway comprises several highly conserved proteins that are involved in spinal cord developmental processes. In the present study, the emerging role of Notch1 in fetal lumbosacral spinal cords was investigated in a rat model of ARMs using ethylene thiourea. Immunohistochemical staining, western blot and quantitative reverse transcription real-time polymerase chain reaction were utilized to analyze spatiotemporal expression of Notch1 on embryonic days (E) 16, E17, E19, and E21. The expression levels of the neuronal marker neurofilament and recombination signal-binding protein-J protein were evaluated for temporal correlations to Notch1 expression. The results implied that Notch1 expression was reduced in lumbosacral spinal cord neurons of ARMs embryos compared to control embryos. These results showed that, in ARMs embryos decreased Notch1 expression is related to the dysplasia of the caudal spinal cord during embryogenesis, indicating that Notch signaling may participate pathogenic embryonic lumbosacral spinal development and may be associated with postoperative complications of ARMs.

A review of genetic factors contributing to the etiopathogenesis of anorectal malformations

BACKGROUND

Anorectal malformation (ARM) is a common congenital anomaly with a wide clinical spectrum. Recently, many genetic and molecular studies have been conducted worldwide highlighting the contribution of genetic factors in its etiology. We summarize the current literature on such genetic factors.

MATERIALS AND METHODS

Literature search was done using different combinations of terms related to genetics in anorectal malformations. From 2012 to June 2017, articles published in the English literature and studies conducted on human population were included.

OBSERVATIONS AND RESULTS

A paradigm shift was observed from the earlier studies concentrating on genetic aberrations in specific pathways to genome wide arrays exploring single nucleotide polymorphisms (SNPs) and copy number variations (CNVs) in ARM patients. Rare CNVs (including 79 genes) and SNPs have been found to genetically contribute to ARM. Out of disrupted 79 genes one such putative gene is DKK4. Down regulation of CDX-1 gene has also been implicated in isolated ARM patients. In syndromic ARM de novo microdeletion at 17q12 and a few others have been identified.

CONCLUSION

Major genetic aberrations proposed in the pathogenesis of ARM affect members of the Wnt, Hox (homebox) genes, Sonic hedgehog (Shh) and Gli2, Bmp4, Fgf and CDX1 signalling pathways; probable targets of future molecular gene therapy.

Anorectal malformation: the etiological factors

Anorectal malformation (ARM) is a congenital anomaly commonly encountered in pediatric surgery practice. Although surgical procedures correct the anatomical anomalies, the post-operative bowel function is not universally satisfactory. The etiology of ARM remains unclear. In this review, we summarize the current understanding of the genetic and epigenetic factors contributing to the pathogenesis of ARM, based on published animal models, human genetics and epidemiological researches. Appreciation of these factors may be helpful in the management of ARM in the future.