Inclusion Criteria:  Males and females, Aged>15 Evidence of enteric dysmotility with documented abnormality on objective testing which may include high resolution esophageal manometry, gastric emptying scintigraphy, SmartPill Wireless Motility Capsule, Sitz marker studies, antroduodenal manometry or anorectal manometry. English proficiency and literacy sufficient to sign consent form and fill out questionnaires. Previous Mayo paraneoplastic panel testing. Referring gastroenterologist has recommended intravenous immunoglobulin (IVIg) therapy.  Exclusion Criteria:  Non-autoimmune causes of enteric dysmotility (diabetes, adrenal insufficiency, Parkinson's, thyroid, electrolytes, drugs, malignancy).  Pregnancy as documented in EPIC with serum or urine Human chorionic gonadotropin (hCG) testing  If participants believe that they are pregnant, they will need to notify a study physician who will order a serum or urine hCG test for pregnancy within EPIC and remove them from the study if the test results come back positive. Previous treatment with IVIg.