Comprehensive analysis of <it>RET </it>common and rare variants in a series of Spanish Hirschsprung patients confirms a synergistic effect of both kinds of events

<p>Abstract</p> <p>Background</p> <p><it>RET </it>is the major gene associated to Hirschsprung disease (HSCR) with differential contributions of its rare and common, coding and noncoding mutations to the multifactorial nature of this pathology. In the present study, we have performed a comprehensive study of our HSCR series evaluating the involvement of both <it>RET </it>rare variants (RVs) and common variants (CVs) in the context of the disease.</p> <p>Methods</p> <p><it>RET </it>mutational screening was performed by dHPLC and direct sequencing for the identification of RVs. In addition Taqman technology was applied for the genotyping of 3 <it>RET </it>CVs previously associated to HSCR, including a variant lying in an enhancer domain within <it>RET </it>intron 1 (rs2435357). Statistical analyses were performed using the SPSS v.17.0 to analyze the distribution of the variants.</p> <p>Results</p> <p>Our results confirm the strongest association to HSCR for the "enhancer" variant, and demonstrate a significantly higher impact of it in male <it>versus </it>female patients. Integration of the <it>RET </it>RVs and CVs analysis showed that in 91.66% of cases with both kinds of mutational events, the enhancer allele is in <it>trans </it>with the allele bearing the <it>RET </it>RV.</p> <p>Conclusions</p> <p>A gender effect exists on both the transmission and distribution of rare coding and common HSCR causing mutations. In addition, these <it>RET </it>CVs and RVs seem to act in a synergistic way leading to HSCR phenotype.</p