Lynch Syndrome (Hereditary Nonpolyposis Colorectal Carcinoma; HNPCC) By Minhhuyen Nguyen, MD, Fox Chase Cancer Center, Temple University Reviewed / Revised Mar 2021 | Modified Sep 2022 View Patient Education Symptoms and Signs Diagnosis Treatment Key Points More Information Lynch syndrome is an autosomal dominant disorder responsible for 2 to 3% of cases of colorectal cancer.