**Abstract**

Advances in cytogenetic, molecular genetic, and molecular cytogenetic techniques have provided convincing evidence in favor of a genetic basis for endometriosis and corroborating the higher prevalence of the disease in first-degree relatives of affected women. The regulatory mechanisms involved in the morphological and biochemical differentiation of the uterine endometrium are obviously complex, but consistent somatic genetic alterations have been identified. A higher percentage of aberrant metaphases showing aneuploidy, dicentric chromosomes, endomitosis, and chromosomal spraying have been detected in several trials. These results were further amplified by multicolored fluorescent in situ hybridization (FISH) analysis demonstrating the presence of alterations, where at least chromosomes 1, 16, 17, and 22 show structural aberrations containing genes that could play a role in the development and/or progression of endometriosis. Overall, the non-random distribution along with the subchromosomal location of the genetic alterations strongly supports the idea that these anomalies are relevant and are associated with the endometriotic process.

**Keywords:** molecular genetic, endometriosis, chromosome, hybridization

### **1. Introduction**

Endometriosis is a systemic, multisymptomatic, and disabling condition for women. Even when endometriosis originates from pelvic implantation, it can spread to other bodily surfaces outside of it.

These endometriosis cells do not shed and migrate like endometrial cells. They remain in situ, causing hemorrhage and an inflammatory response during each hormonal cycle, conditioning the different symptoms and complications in each affected organ.

Although the pathophysiological mechanism has been well studied, the cause of endometriosis remains uncertain. This fact has motivated the development of multiple and diverse theories that have tried to explain this pathology. The biggest problem is that they have been exclusionary theories, so they have not been able to define a cause that fits different scenarios.

It is under this concept and with the advent of new techniques of genetic and molecular study that new theories have been developed based on genetic changes and molecular alterations, which, being inclusive, provide a better vision of the origin of endometriosis and of the way it manages to develop much more effective therapeutic strategies.

In this chapter, we will discuss some aspects of the molecular genetic approach, with relevant findings on the definition and pathogenesis of endometriosis
