Colour says it all

A 14-year-old girl presented with persistent conjugated hyperbilirubinemia (Serum Bilirubin – 99.18 μmol/L (total), 63.27 μmol/L (conjugated)) with normal serum transaminases (Aspartate aminotransferase – 17 U/L and Alanine aminotransferase – 16 U/L) and a normal systemic examination. Her full blood count, coagulation profile, thyroid function test, renal function test and serologies for viral hepatitis and chronic liver disease were normal. Ultrasound abdomen showed mild hepatomegaly (liver span – 15.8 cm) with normal echotexture and outline. A liver biopsy was completed, which showed jet black coloured tissue (Fig. 1). Identify the condition – (Answer on page 468)