Homeobox (HOX) gene has been discovered by Dr. Calvim Blackman in the year 1921 from a fruit fly, which has explained the segmental replacement of legs in antennae location. It has been indicated by different scientists that HOX gene usually preserve a major relationship, which is also known as collinearity. Each of the HOX cluster is comprised of 11 genes, which has been organized in a proper linear fashion that is parallel to the expression along with different axes of the body. From the perspective of the human body, the function of HOX gene is related to transcription of different factors, which are regulated according to the series of downstream gene pathways.
HOX gene also plays a major role in the human body, in regards of the female reproductive system. It has been evaluated that HOX gene is widely regulated by estrogen in female reproductive tract embryogenesis. From this perspective, the collinearity of HOX genes is widely preserved during the development of Mullerian duct. An extremely low amount of data has been presented about the process of endometriosis because of HOX gene. It has been evaluated that endometriosis usually underwent malignant transformation to the endometrioid and ovarian cancers because of HOX gene involvement. On the contrary, it has been also observed that Mullerian ducts are originated from the coelomic cavity of epithelium in embryo where the differentiation of different uterine tube, fallopian tubes, oviducts, cervix, and uterine corpus has been regulated by HOXA9, A10, and A11 genes. Similarly, HOXA10 cluster has also played a major role in the implantation of embryo.During endometriosis, the expression in regards of HOXA10 has not exhibited mid-luteal rise, which has been witnessed during normal endometrium that might contribute the infertility among women through endometriosis.
HOXB4 is considered as one of the four HOX group 4 paralogs in regards of Antennapedia (ANTP) homeobox superfamily genes. This gene is located on chromosome 17 in the human body. Along with that, this gene encodes a nuclear protein that functions as a transcription factor implicated in cellular differentiation and development. Among mice, HOXB4 is widely expressed during the process of embryogenesis in two germ layers (neural tube epithelium and mesoderm). In the adult mice, HOXB4 is usually expressed in kidneys, lungs, and testes. In humans, HOXB4 has been studied lengthily in the hematopoietic stem (HS) and progenitor cells in vivo and in vitro. In vitro, all such genes were found to stimulate proliferation and inhibit differentiation in hematopoietic precursors.