Two locus analyses of variants showed significant interactions with increased and decreased disease risks of HSCR at NRG1 but conditional on rs2435357 genotype.
Furthermore, individuals with five or six risk alleles at RET rs2506030, rs2435357 and NRG1 rs7835688 showed ∼45-fold higher HSCR risk than those with 0 or 1 or 2 risk alleles.
In addition Taqman technology was applied for the genotyping of 3 RET CVs previously associated to HSCR, including a variant lying in an enhancer domain within RET intron 1 (rs2435357).
Excluding the rare variant carriers from the genome-wide association analysis did not appreciably change the association of rs2435357 with Hirschsprung disease.
RET rs2506030 (GG genotype) and rs2435357 (TT genotype), in combination with NRG1 rs2439302 (GG genotype), were strongly associated with the highest risk of HSCR (OR = 56.53, P = 4.50E-07) compared with the two loci or a single SNP of either RET or NRG1.
The RET-protooncogene rs2435357 (TT genotype) in combination with the NRG1 rs2439305 (GG genotype) was strongly associated with an increased risk of HSCR with a P-value of 1.99E-04 (OR=20.34, 95% CI; 2.54-162.78) when compared with a single SNP of the RET-protooncogene or NRG1.
Excluding the rare variant carriers from the genome-wide association analysis did not appreciably change the association of rs2435357 with Hirschsprung disease.
Colon tissue DNA samples showed similar frequency of SNPs as that of the blood DNA samples in HSCR patients, both of which are significantly higher than the control blood group (rs2435357 TT genotype: 71.2%, 74.7% versus 22.0% in HSCR blood, HSCR colon and control blood DNA respectively, P=0.000; rs2506004 AA genotype: 72.4%, 83.1% versus 25.5%, P=0.000; rs2506030 GG genotype: 79.7%, 77.2% versus 54.2%, P=0.000 and 0.004).
Particularly variant alleles of rs1864410, rs2435357, rs2506004 (intron 1), rs1800858 (exon 2), rs1800861 (exon 13), and rs2565200 (intron 19) were strongly associated with increased risk of HSCR (p<0.00000) and were over-represented in males vs. females.
Two noncoding variations in RET-the T allele of the single nucleotide polymorphism (SNP) rs2435357 (Enh1:C>T) and the A allele of the SNP rs2506004 (Enh2:C>A)-are associated with Hirschsprung's disease.
One patient having a mutation in exon 16 (Met918Thr) presented with the MEN2B phenotype, six patients from two families had hereditary MTC without pheochromocytoma (pheo) and primary hyperparathyroidism (PHPT), whereas 33 patients from 15 families showed the MEN2A phenotype.
Mutation analysis of exon 16 of the RET proto-oncogene revealed germline M918T and thus, a molecular diagnosis of multiple endocrine neoplasia type 2B (MEN 2B).