METHODOLOGY ARTICLE Open Access Increasing gene discovery

Full list of author information is available at the end of the articleBackground Blood is a valuable resource to probe an animal’s physiological and pathological status as well as to obtain repeated samples before harvest, for example, monitoring the dynamic change of gene expression in response to disease, treatment, or aging, for which the onset of gene expression response is not known. However, transcriptomic analysis of blood samples is a challenge since blood is composed of heterogeneous cell types including red blood cells (99%), platelets (1%) and white blood cells (<1%; e.g., neutrophils, monocytes, basophils, lymphocytes and eosinophils) [1,2]. In human blood, HBA and HBB are the most abundant transcripts (~52-76%) [3,4]. The high level of globin transcripts in blood was reported to be the most limiting factor for accurate and sensitive detection of gene expression, especially for the less abundant transcripts [3-5]. This issue is a great concern for sequence-based approaches, in which the globin transcript