Final answer:
Turner Syndrome is the disorder associated with an increased risk of endometrial cancer, celiac disease, and structural heart defects. It's characterized by the presence of only one X chromosome in females.
Step-by-step explanation:
The disorder of sexual development that is associated with an increased risk of endometrial cancer, celiac disease, and structural heart defects is Turner Syndrome. Turner Syndrome is a chromosomal disorder where a female is born with only one X chromosome (45,X instead of 46,XX or 46,XY). This can lead to various developmental and medical issues including heart defects, absence of menstrual cycle, and an increased risk for certain autoimmune disorders like celiac disease. Endometrial cancer risk is elevated due to the unopposed estrogen exposure that can occur in individuals who don't have regular menstrual cycles due to ovarian failure, which is also common in Turner Syndrome. A vegan diet does not directly increase the risk of Turner Syndrome but may relate to other health concerns like deficiencies in iron or vitamin B12.