Association of <i>NOS3</i> and <i>HIF</i>1<i>α</i> gene polymorphisms with the susceptibility of broiler chickens to develop hypoxic pulmonary hypertension

Abstract

A genetic association between single nucleotide polymorphisms (SNPs) and pulmonary hypertension syndrome (PHS) was established in a commercial population of broiler chickens. The associated SNPs were found in the NOS 3 and HIF 1 α genes (LOD > 6; p < 0.001). The SNPs in the NOS 3 gene interfere with its trans -activation and transcriptional activation activities under natural hypobaric hypoxia conditions and are located in a consensus sequence that is called the hypoxia response element (HRE). SNPs located in the HIF 1 α gene could act as alternative cryptic splicing sites in intron six, which may stimulate non-sense mediated early decay (NMD) of the primary transcript. A fragment of intron 3 of the EDN 1 gene was also evaluated, but the polymorphisms found were not associated with PHS ( lod < 6; p > 0.001). However, further studies on the regulatory transcription sequences of EDN 1 are recommended. The findings of this study indicate that intronic sequences should be included when searching for polymorphisms that produce physiological changes. Introns have transcriptional regulatory sequences or post-transcriptional control signals, which are known as cis- and trans -activation regulatory elements and are able to alter the physiological processes of hypoxia adaptation when modified. Based on these findings, it can be concluded that the inheritance pattern of PHS is autosomal overdominant and has deleterious effects that are characterized by higher penetrance in heterozygous than in homozygous animals, which prevent broiler chickens from being able to adapt to high altitudes.