A recent study conducted by a team of researchers from the University of British Columbia and Johns Hopkins Medicine discovered set of genetic mutations in tissue samples collected from 24 women, who had been diagnosed with benign endometriosis, a condition in which abnormal growth of endometrial cells growth outside the wound. The findings could potentially help researchers in the development of molecular tests to differentiate between non-aggressive or clinically “indolent” and aggressive forms of endometriosis.
Endometriosis in the endometrium, lining of the uterus, forms and grows on the outside of the uterus. The condition affects about 10 percent of women prior to the menopause onset and half of those with infertility problems and abdominal pain. Gynecologist John Sampson, a Johns Hopkins graduate, invented the term “endometriosis” and suggested the theory endometriosis derived from when normal endometrial tissue flowed out of the fallopian tubes directly into the abdominal cavity during the menstrual cycle.
The new study challenges that theory. The unusual set of mutations discovered in the tissue samples purposes that while the origins of endometriosis are embedded in normal endometrial cells, their fate was altered by acquired mutations.
The researchers say the reasons are not exactly clear yet, but the identified mutations have some connects to the similar genetic mutations discovered in various forms of cancer. Even though abnormal tissue growth in endometriosis frequently spreads all throughout the abdominal cavity, it seldom becomes malignant, except when the ovaries are involved, which is only a few cases.
The researchers sequenced a part of the genome called exome that consists of both endometriosis tissue and normal tissue collected from the 24 women during laparoscopic biopsies, containing “some with more than one abnormal endometrial growth.” All of the women had been diagnosed with deep infiltrating endometriosis, a form of the condition that causes infertility and pain.
Seventeen of the participants were patients at the Lenox Hill Hospital-Northwell Health in New York City and the other seven were from Japan. The tissue sample collected from the Japanese women was chosen because endometriosis prior to the onset of menopause occurs (13-18 percent) more frequently in women of Asian descent than in Caucasian women (6-10 percent).
The researchers searched for mutations, abnormal alterations in DNA, removed the normal variations in genes that normally occur among all humans. Nineteen of the 24 women had no mutations in their normal tissue, but had one or more in their endometriosis tissue.
The number and type of mutations varied between each woman and endometriosis lesion. The most common mutations that occurred in only five of the women occurred in several types of genes, including PPP2R1A, KRAS, ARID1A and PIK3CA, which are all known for regulating cell invasion, DNA damage repair and cell growth.
The mutations found in these genes have been linked with clear cell carcinoma, one of the deadliest forms of ovarian cancer.
The study was published in the New England Journal of Medicine on May 11, 2017.