Mutational Spectrum of Semaphorin 3A and Semaphorin 3D Genes in Spanish Hirschsprung patients

Abstract

Hirschsprung disease (HSCR, OMIM 142623) is a developmental disorder characterized by the absence of ganglion cells along variable lengths of the distal gastrointestinal tract, which results in tonic contraction of the aganglionic colon segment and functional intestinal obstruction. The RET proto-oncogene is the major gene associated to HSCR with differential contributions of its rare and common, coding and noncoding mutations to the multifactorial nature of this pathology. In addition, many other genes have been described to be associated with this pathology, including the semaphorins class III genes SEMA3A (7p12.1) and SEMA3D (7q21.11) through SNP array analyses and by next-generation sequencing technologies. Semaphorins are guidance cues for developing neurons implicated in the axonal projections and in the determination of the migratory pathway for neural-crest derived neural precursors during enteric nervous system development. In addition, it has been described that increased SEMA3A expression may be a risk factor for HSCR through the upregulation of the gene in the aganglionic smooth muscle layer of the colon in HSCR patients. Here we present the results of a comprehensive analysis of SEMA3A and SEMA3D in a series of 200 Spanish HSCR patients by the mutational screening of its coding sequence, which has led to find a number of potentially deleterious variants. RET mutations have been also detected in some of those patients carrying SEMAs variants. We have evaluated the A131T-SEMA3A, S598G-SEMA3A and E198K-SEMA3D mutations using colon tissue sections of these patients by immunohistochemistry. All mutants presented increased protein expression in smooth muscle layer of ganglionic segments. Moreover, A131T-SEMA3A also maintained higher protein levels in the aganglionic muscle layers. These findings strongly suggest that these mutants have a pathogenic effect on the disease. Furthermore, because of their coexistence with RET mutations, our data substantiate the additive genetic model proposed for this rare disorder and further support the association of SEMAs genes with HSCR.

Semaphorin 3d signaling defects are associated with anomalous pulmonary venous connections

“…The F602L variant is predicted to be possibly damaging to protein function by PolyPhen in silico analysis ( Supplementary Table 1 ), and the amino acid alteration is located in the immunoglobulin-like domain of Sema3d, which has been shown to be important for both receptor binding and functional activity 33,34 . Additionally, the F602L variant is absent from the 1000 Genomes data set (1,092 individuals) and the National Heart, Lung, and Blood Institute Exome Sequencing Project (ESP) (13,000 chromosomes) 35 and is not among the >800 chromosomes reported previously in which SEMA3D exons were sequenced for other reasons 36,37 .…”

Involvement of DNMT3B in the pathogenesis of Hirschsprung disease and its possible role as a regulator of neurogenesis in the human enteric nervous system

“…[2][3][4][5][6][7][8][9][10][11] HSCR is regarded as a disorder with complex genetic basis. The contribution of different mutational events within several loci acting in an additive manner is usually involved in the development of this disease.…”

Congenital diseases and semaphorin signaling: Overview to date of the evidence linking them

“…; Luzón‐Toro et al. ). In addition, the relationship between two SEMA3A polymorphisms and the risk of HSCR in a Chinese population was verified (Wang et al.…”