2438 An Unusual Cause of Jaundice: A Rare Diagnosis of Crigler-Najjar Type 2

Abstract

INTRODUCTION: Crigler Najjar is an uncommon genetic disorder that results in elevated unconjugated bilirubin due to its impaired conjugation and excretion within the liver. Here we report a case of this unusual disorder in a relatively asymptomatic patient. CASE DESCRIPTION/METHODS: A 21-year-old woman with no significant past medical history presented with 1 year of intermittent jaundice, 20 pound unintentional weight loss, and decreased appetite. The patient reported recent travel to Cuba, but denied any known sick contacts. She also denied any pruritis, abdominal pain, nausea, or diarrhea. Her family history was notable for pancreatic adenocarcinoma. Social history was unremarkable. On physical exam, the patient was ill appearing with moderate scleral icterus and jaundice. Lab work demonstrated isolated unconjugated hyperbilirubinemia (Total Bilirubin: 7.5, conjugated: 0.4, unconjugated: 7.1). Right upper quadrant ultrasound and CT abdomen and pelvis were unrevealing as to the etiology of the patient's hyerbilirubinemia. Extensive testing for a variety of infectious, hereditary, hematological, and rheumatologic disorders were all negative as well. Further advanced genetic testing revealed a heterozygous UGT1A1 gene mutation, ultimately diagnosing the patient with Crigler-Najjar type 2 (CN2). Her symptoms resolved spontaneously without any intervention. DISCUSSION: CN2 is due to a partial deficiency of the enzyme uridine diphosphate-glucuronyl transferase (UGT1A1). Unlike the homozygous form of the disease where there is a total deficiency of the enzyme, usually resulting in death at an early age, the heterozygous form (type 2) is typically more benign in its course. While patients are relatively asymptomatic, they can develop hyperbilirubinemia in stressful situations, after surgery, or with certain medications. It is important to consider CN2 in patients with intermittent unconjugated hyperbilirubinemia. This is especially true in young women, such as this patient, as it can affect neonates during pregnancy. Unfortunately, due to the low prevalence of this, it is often a diagnostic challenge for clinicians.