Which are the causes of BPES - Blepharophimosis Ptosis Epicanthus Inversus Syndrome?

BPES (Blepharophimosis Ptosis Epicanthus Inversus Syndrome) is a rare genetic disorder that affects the development of the eyelids and other facial features. It is characterized by a combination of four main features: blepharophimosis, ptosis, epicanthus inversus, and telecanthus.

Blepharophimosis refers to the narrowing of the eyelid fissure, which is the opening between the upper and lower eyelids. This results in a reduced width of the eye opening, giving the eyes a slanted appearance. The eyelids may also have a droopy or hooded appearance, known as ptosis. Ptosis can vary in severity, ranging from mild to severe, and can affect one or both eyes.

Epicanthus inversus is another characteristic feature of BPES. It refers to the presence of a fold of skin that covers the inner corner of the eye, giving the appearance of a "folded" or "upside-down" eyelid. This feature can further contribute to the slanted appearance of the eyes.

Telecanthus is the term used to describe an increased distance between the inner corners of the eyes. This can give the eyes a widely spaced appearance.

The exact causes of BPES are primarily genetic. The syndrome is typically inherited in an autosomal dominant manner, which means that an affected individual has a 50% chance of passing the condition on to each of their children. The majority of cases are caused by mutations in two genes: FOXL2 and BMP4.

FOXL2 gene mutations are the most common cause of BPES. The FOXL2 gene provides instructions for producing a protein that is involved in the development of various tissues, including the eyelids and ovaries. Mutations in this gene disrupt the normal development of these tissues, leading to the characteristic features of BPES.

BMP4 gene mutations are less common but can also cause BPES. The BMP4 gene is involved in the regulation of embryonic development, including the formation of facial structures. Mutations in this gene can disrupt the normal development of the eyelids and other facial features, resulting in BPES.

It is important to note that not all individuals with BPES have a family history of the condition. In some cases, the syndrome may occur sporadically due to new mutations in the FOXL2 or BMP4 genes.

While the genetic causes of BPES are well-established, the specific mechanisms by which these gene mutations lead to the characteristic features of the syndrome are still being studied. Researchers continue to investigate the underlying biological processes involved in the development of BPES in order to gain a better understanding of the disorder and potentially develop targeted treatments in the future.