Endometriosis is a condition that affects an estimated 1 in 10 women worldwide. Despite how common the condition is, however, it’s still poorly understood. On the surface, endometriosis can sound like a fairly straightforward disease, but in reality, it is incredibly complex.

What Is Endometriosis?

The endometrium, or endometrial tissue, normally lines the inside of the uterus, and it is shed during a menstrual period. Endometriosis occurs when tissue similar to the endometrium grows in locations outside the uterus. Endometriosis can involve the uterus, ovaries, fallopian tubes, and other organs in the abdomen and pelvis.

Common symptoms of endometriosis include:

• Pelvic pain
• Abdominal pain
• Dysmenorrhea (painful menstrual cycles)
• Dyspareunia (pain during sexual intercourse)
• Bloating
• Fertility problems
• Abdominal adhesions (scar tissue that forms on internal organs)

A confirmed diagnosis of endometriosis can only be made with laparoscopy. During this minimally invasive surgical procedure, a surgeon inserts a laparoscope — a slender tube with a light and camera — to explore a person’s pelvis and abdomen.

Treatments for endometriosis can include:

• Surgery to remove abnormal tissue and adhesions
• Hormonal birth control to lower estrogen levels and control ovulation
• In severe cases, hysterectomy, a surgery where the uterus is removed

What Makes a Disease Hereditary?

Hereditary diseases are diseases that are caused, at least in part, by genetic changes inherited from one or both parents. Some hereditary diseases can be traced to specific genetic mutations that cause a disease, such as spinal muscular atrophy (SMA), which is caused by an inherited mutation of what’s called the SMN1 gene.

Other diseases, such as breast cancer, can occur without any family history, but having inherited mutations of the BRCA1 and BRCA2 genes can significantly increase a person’s risk of developing certain types of cancer.

Some diseases have not been linked to specific genes but can run in families, such as type 2 diabetes and heart disease. Many diseases, including heart disease, have both genetic and environmental risk factors.

Is Endometriosis Hereditary?

Endometriosis can be hereditary. More specifically, a family history of endometriosis increases your odds of developing the condition. Several studies have shown that endometriosis appears more often in clusters of related individuals. Some research suggests that about 51 percent of endometriosis cases are at least partially due to genetics.

According to one study, having a first-degree family member (parent, child, or sibling) with endometriosis can make you 7 to 10 times more likely to develop the disease. A person’s risk of developing endometriosis is also higher for people with second- and third-degree relatives with the condition, including aunts, nieces, cousins, grandparents, and grandchildren.

However, genetic factors alone do not determine whether or not an individual will develop endometriosis. Environmental factors also play a role.

What Causes Endometriosis?

The causes of endometriosis are poorly understood, but it is believed that both genetic and environmental factors contribute to its development. Examples of environmental factors include exposure to chemicals, such as dioxins, and increased exposure to estrogen produced by the body.

Exactly how genes and environment work together to set the stage for endometriosis is unclear, but recent research has shed light on some possible explanations.

Genetics and Endometriosis

While the underlying causes of endometriosis clearly have a genetic component, it is unclear exactly which genes are involved. Researchers have identified dozens of potential genes and gene variants (mutations) that may contribute to the development of endometriosis.

Many different biological mechanisms are involved in the development of endometriosis, and many different proteins and genes are part of those mechanisms. Any of the genes and proteins involved are potentially susceptible to mutations that could contribute to the condition.

Not all gene mutations are inherited — some are acquired during a person’s lifetime. Acquired genetic mutations can occur due to normal aging, certain viral infections, and environmental exposures, including radiation and toxicants (human-made toxins). Only mutations that are present in eggs and sperm can be passed to offspring.

While genetic mutations are an important part of heredity, there is more to the story of how genetic changes are passed from one generation to the next.

Epigenetics and Endometriosis

Recent research has identified potential epigenetic factors associated with endometriosis. Epigenetic changes are another type of inherited genetic change. Epigenetic changes to DNA do not alter the DNA sequence, but they change which parts of a cell’s DNA are available to make proteins.

Several different mechanisms produce epigenetic changes in DNA by either increasing or decreasing which genes are made into protein. Essentially, epigenetic changes can turn individual genes “off” and “on.”

Epigenetic changes can occur in response to environmental factors such as stress, disease, or malnutrition. These changes can occur at any point in a person’s life, including while in the womb before birth. Some research suggests that certain epigenetic marks can also be passed down to the next generation.

What Does This Mean for Me?

Understanding that endometriosis can be hereditary is important if you or a relative has the condition. Let your doctor know if you have a family history of endometriosis. This can help them in diagnosing potential symptoms of endometriosis, identifying causes of infertility, and selecting types of hormonal contraceptives (birth control).

Talk With Others Who Understand

MyEndometriosisTeam is the social network for people with endometriosis and their loved ones. On MyEndometriosisTeam, more than 127,000 members come together to ask questions, give advice, and share their stories with others who understand life with endometriosis.

Are you or someone you care for living with endometriosis? Share your experience in the comments below, or start a conversation by posting on your Activities page.