Gastrointestinal Disorders

4 conditions|3 ABGC-listed

Overview

GI genetics includes hepatobiliary conditions, metal metabolism disorders, and disorders of intestinal innervation.

Gastrointestinal genetic disorders

This section covers conditions affecting the GI tract, liver, and metal metabolism. Know the classic presentations: Hirschsprung (no meconium, absent ganglion cells), Wilson (liver + neuro + Kayser-Fleischer rings), Alagille (cholestasis + heart + butterfly vertebrae), and hemochromatosis (iron overload, "bronze diabetes"). Wilson and hemochromatosis are treatable if caught early.

Alagille syndrome

ABGC

An infant with cholestatic jaundice has a characteristic triangular face, butterfly vertebrae on X-ray, and posterior embryotoxon on eye exam. Echocardiogram reveals peripheral pulmonary stenosis.

Hereditary hemochromatosis

ABGC

A 50-year-old man presents with fatigue, joint pain, and elevated liver enzymes. He has bronze-colored skin and diabetes. Transferrin saturation is 75% and ferritin is 2000 ng/mL.

Hirschsprung disease

A newborn fails to pass meconium in the first 48 hours and develops abdominal distension. Contrast enema shows a transition zone in the rectosigmoid. Rectal biopsy confirms absent ganglion cells.

Wilson disease

ABGC

A 15-year-old presents with tremor and dysarthria. Slit-lamp exam reveals Kayser-Fleischer rings. Liver enzymes are mildly elevated. Ceruloplasmin is low and 24-hour urine copper is elevated.

Summary Table

Disorder	Gene	Inheritance	Cardinal Features
Hirschsprung	RET, others	Complex	Absent ganglion cells, no meconium passage
Wilson	ATP7B	AR	Liver + neuro, KF rings, low ceruloplasmin
Alagille	JAG1	AD	Bile duct paucity, butterfly vertebrae, cardiac
Hemochromatosis	HFE	AR	Iron overload, bronze diabetes, cirrhosis

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