How to approach understanding complex trait genetics – inflammatory bowel disease as a model complex trait

摘要

Monogenic disorders are individually rare, run in families based on classic modes of inheritance termed Mendelian inheritance (autosomal dominant or recessive, X-linked), and are caused by variation within a single gene. The involved variants are rare and typically disrupt protein-coding genes thereby causing disease. Monogenic traits are however rare. Many -- if not most -- traits are associated with a familial risk, without demonstrating a typical Mendelian inheritance pattern. The lack of a Mendelian inheritance pattern however does not exclude a genetic origin. These common traits are classified as complex – or multifactorial – traits, caused by variation within multiple genes (polygenic) and environmental factors.