Gastrointestinal & Hepatology syndromes.

Gene/chromosome: UGT1A1, chromosome 2; Inheritance: Usually autosomal recessive; Triad: Mild intermittent unconjugated hyperbilirubinemia, jaundice during fasting, normal liver enzymes; Associated: No increased malignancy risk; Investigation: Isolated unconjugated bilirubin elevation with normal LFTs

Gene/chromosome: UGT1A1, chromosome 2; Inheritance: Autosomal recessive; Triad: Severe neonatal unconjugated hyperbilirubinemia, kernicterus, absent bilirubin conjugation; Associated: Neurologic injury; Investigation: Markedly elevated unconjugated bilirubin, absent response to phenobarbital

Gene/chromosome: UGT1A1, chromosome 2; Inheritance: Autosomal recessive; Triad: Moderate unconjugated hyperbilirubinemia, jaundice, partial enzyme activity; Associated: Kernicterus uncommon; Investigation: Bilirubin reduction with phenobarbital

Gene/chromosome: ABCC2, chromosome 10; Inheritance: Autosomal recessive; Triad: Conjugated hyperbilirubinemia, recurrent jaundice, otherwise normal liver function; Associated: Black liver pigmentation; Investigation: Urinary coproporphyrin I predominance

Gene/chromosome: SLCO1B1 and SLCO1B3, chromosome 12; Inheritance: Autosomal recessive; Triad: Conjugated hyperbilirubinemia, intermittent jaundice, normal liver histology; Associated: No characteristic malignancy; Investigation: Increased total urinary coproporphyrins with predominance of coproporphyrin I

Gene/chromosome: ATP7B, chromosome 13; Inheritance: Autosomal recessive; Triad: Hepatic disease, neuropsychiatric symptoms, Kayser-Fleischer rings; Associated: Hemolytic anemia, cirrhosis; Investigation: Low ceruloplasmin, increased urinary copper, slit-lamp examination

Gene/chromosome: HFE, chromosome 6; Inheritance: Usually autosomal recessive; Triad: Cirrhosis, diabetes, skin pigmentation; Associated: Hepatocellular carcinoma, cardiomyopathy, hypogonadism; Investigation: Increased transferrin saturation and ferritin, HFE testing

Gene/chromosome: SERPINA1, chromosome 14; Inheritance: Codominant; Triad: Emphysema, liver disease, panniculitis; Associated: Hepatocellular carcinoma, COPD; Investigation: Low alpha-1 antitrypsin level, PAS-positive diastase-resistant hepatocyte globules

Gene/chromosome: Sporadic gastrinoma or MEN1-associated; Inheritance: Sporadic or autosomal dominant in MEN1; Triad: Recurrent peptic ulcers, diarrhea, hypergastrinemia; Associated: MEN1, pancreatic/duodenal NET; Investigation: Fasting serum gastrin with gastric pH, secretin stimulation test

Gene/chromosome: Tropheryma whipplei infection; Inheritance: Not inherited; Triad: Diarrhea, weight loss, arthralgia; Associated: Neurologic and cardiac involvement; Investigation: PAS-positive macrophages in small-bowel biopsy, PCR

Gene/chromosome: HLA-DQ2/DQ8 association; Inheritance: Multifactorial; Triad: Chronic diarrhea, malabsorption, iron-deficiency anemia; Associated: Dermatitis herpetiformis, enteropathy-associated T-cell lymphoma; Investigation: Anti-tTG IgA with total IgA, duodenal biopsy

Gene/chromosome: STK11, chromosome 19; Inheritance: Autosomal dominant; Triad: Hamartomatous polyps, mucocutaneous pigmentation, intussusception; Associated: Pancreatic, breast, ovarian, gastrointestinal cancers; Investigation: STK11 testing, endoscopy

Gene/chromosome: APC, chromosome 5; Inheritance: Autosomal dominant; Triad: Numerous colorectal adenomas, early colorectal cancer, family history; Associated: Desmoid tumors, osteomas, duodenal cancer; Investigation: Colonoscopy, APC testing

Gene/chromosome: MLH1, MSH2, MSH6, PMS2, EPCAM; Inheritance: Autosomal dominant; Triad: Early colorectal cancer, endometrial cancer, family history; Associated: Colorectal, endometrial, ovarian, gastric, urinary tract cancers; Investigation: Tumor mismatch-repair immunohistochemistry or MSI testing

Gene/chromosome: APC, chromosome 5; Inheritance: Autosomal dominant; Triad: Colonic polyposis, osteomas, dental abnormalities; Associated: Colorectal carcinoma, desmoid tumors; Investigation: Colonoscopy, APC testing

Gene/chromosome: CDH1, chromosome 16; Inheritance: Autosomal dominant; Triad: Diffuse gastric cancer, signet-ring histology, family history; Associated: Lobular breast carcinoma; Investigation: CDH1 testing, upper GI surveillance

Gene/chromosome: No single gene; Inheritance: Acquired; Triad: Abdominal pain, hepatomegaly, ascites; Associated: Myeloproliferative neoplasms, thrombophilia; Investigation: Doppler ultrasound showing hepatic venous outflow obstruction

Gene/chromosome: PKHD1 association in some cases; Inheritance: Often autosomal recessive when associated with ARPKD; Triad: Intrahepatic bile duct dilatation, recurrent cholangitis, hepatolithiasis; Associated: Congenital hepatic fibrosis, portal hypertension; Investigation: MRCP showing saccular intrahepatic bile duct dilatation