Reduced RET expression in gut tissue of individuals carrying risk alleles of Hirschsprung's disease

Abstract

Receptor tyrosine kinase (RET) single nucleotide polymorphisms (SNPs) are associated with the Hirschsprung's disease (HSCR). We investigated whether the amount of RET expressed in the ganglionic gut of human was dependent on the genotype of three regulatory SNPs (-5G>A rs10900296 and -1A>C rs10900297 in the promoter, and C>T rs2435357 in intron 1). We examined the effects of three regulatory SNPs on the RET gene expression in 67 human ganglionic gut tissues using quantitative real-time PCR. Also, 315 Chinese HSCR patients and 325 ethnically matched controls were genotyped for the three SNPs by polymerase chain reaction (PCR) and direct sequencing. The expression of RET mRNA in human gut tissue did indeed correlate with the genotypes of the individuals. The lowest RET expression was found for those individuals homozygous for the three risk alleles (A-C-T/A-C-T), and the highest for those homozygous for the 'wild-type' counterpart (G-A-C/G-A-C), with expression values ranging from 218.32 +/- 125.69 (mean +/- SE) in tissues from individuals carrying G-A-C/G-A-C to 31.42 +/- 8.42 for individuals carrying A-C-T/A-C-T (P = 0.018). As expected, alleles -5A, -1C and intron 1 T were associated with HSCR (P = 5.94 x 10(-31), 3.12 x 10(-24) and 5.94 x 10(-37), respectively) as was the haplotype encompassing the three associated alleles (A-C-T) when compared with the wild-type counterpart G-A-C (chi2 = 155.29, P << 0.0001). To our knowledge, this is the first RET expression genotype-phenotype correlation study conducted on human subjects to indicate common genetic variants in the regulatory region of RET may play a role in mediating susceptibility to HSCR, by conferring a significant reduction of the RET expression.

Male and female differential reproductive rate could explain parental transmission asymmetry of mutation origin in Hirschsprung disease

“…19 However, this hypothesis was unlikely for HSCR as RET expression is biallelic in the gut. 20 The question of a sperm-specific fitness explaining the parental transmission asymmetry, that is, a selective advantage for spermatozoids not carrying a RET CDS mutation, could also be raised, as the RET gene is known to play a crucial role in early spermatogenesis. 21 However, a selective advantage, 22 and not disadvantage, has been described for spermatogonia carrying a RET mutation.…”

RET Variants and Haplotype Analysis in a Cohort of Czech Patients with Hirschsprung Disease

“…To date, more than 14 genes and 5 susceptibility loci have been associated with the disease [1], [2]. However, the inactivating germline mutations in the RET proto-oncogene play the major role in the pathogenesis.…”

“…The investigation of the strong association of rs1800858 (p.Ala45Ala, c.135G/A) with HSCR was extended upstream of exon 2 to intron 1 and promoter. A haplotype spanning 27 kb of the 5′UTR region to exon 2 was determined as HSCR-associated [2], [6]–[8]. The investigation of 3′UTR variants underrepresented in HSCR patients resulted in the suggestion of the protective haplotype in 3′UTR [9]–[10].…”

Potential Association of <b><i>INMT</i></b> Nonsynonymous Variant (His46Pro) with Hirschsprung's Disease

“…In the study, the rs2435357 mutation within a conserved enhance-like region in the intron 1 induced a transcriptional decrease of RET . In another study, an RET haplotype carrying rs10900296 , rs10900297 and rs2435357 has been associated with RET mRNA expression in human gut tissue and thus with HSCR [9] .…”