Mutation of RET proto-oncogene in Hirschsprung's disease and intestinal neuronal dysplasia.

Aim: To investigate the genetic relationship between Hirschsprung's disease (HD) and intestinal neuronal dysplasia (IND) in Chinese population.

Methods: Peripheral blood samples were obtained from 30 HD patients, 20 IND patients, 18 HD/IND combined patients and 20 normal individuals as control. Genomic DNA was extracted according to standard procedure. Exons 11,13,15,17 of RET proto-oncogene were amplified by polymerase chain reaction (PCR). The mutations of RET proto-oncogene were analyzed by single strand conformational polymorphism (SSCP) and sequencing of the positive amplified products was performed.

Results: Eight germline sequence variants were detected. In HD patients, 2 missense mutations in exon 11 at nucleotide 15165 G-->A (G667S), 2 frameshift mutations in exon 13 at nucleotide 18974 (18974insG), 1 missense mutation in exon 13 at nucleotide 18919 A-->G (K756E) and 1 silent mutation in exon 15 at nucleotide 20692 G-->A(Q916Q) were detected. In HD/IND combined patients, 1 missense mutation in exon 11 at nucleotide 15165 G-->A and 1 silent mutation in exon 13 at nucleotide 18888 T-->G (L745L) were detected. No mutation was found in IND patients and controls.

Conclusion: Mutation of RET proto-oncogene is involved in the etiopathogenesis of HD. The frequency of RET proto-oncogene mutation is quite different between IND and HD in Chinese population. IND is a distinct clinical entity genetically different from HD.