Crohn’s disease belongs to a group of conditions known as inflammatory bowel diseases or IBD. Crohn’s disease is an inflammatory bowel disease that causes chronic inflammation of the gastrointestinal tract. It can affect any part of the GI tract from the mouth to the anus and can affect the entire thickness of the bowel wall. Inflammation of the intestine can "skip," or leave normal areas in between patches of diseased intestine. 

The most common symptoms of Crohn's disease include abdominal pain, tiredness, increased bowel movements, nausea, bloating, fevers, joint pain, loss of appetite, and weight loss.

Crohn's disease may lead to one or more of the following complications - Bowel obstruction, Ulcers, Fistulas, Anal fissures, Malnutrition, Colon cancer, Skin disorders, and Blood clots. Other body organs may also experience problems as a consequence of Crohn's disease. Low iron levels (anaemia), osteoporosis, arthritis, and gallbladder or liver disease are a few of these issues.

References:

1. https://www.crohnscolitisfoundation.org/what-is-crohns-disease/overview