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Dubin-Johnson syndrome
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Homem de 42 anos, sem antecedentes médicos relevantes, apresenta-se com icterícia ligeira persistente, fadiga e sem sinais de doença hepática crónica. Nos testes laboratoriais não se verificaram quaisquer alterações aos valores de referência, com exceção de hiperbilirubinémia (bilirrubina total 7,76 mg/dL, bilirrubina conjugada 5,50 mg/dL), aumento no cobre urinário (2,44 mol/24 horas) e aumento da coproporfirina I urinária (86% da excreção total de coproporfirinas na urina). O estudo genético detetou a presença da mutação NM_000392.5:c.1483A>G no gene ABCC2 em heterozigotia. Neste contexto, assumiu-se o diagnóstico de Síndrome de Dubin-Johnson.
O síndrome de Dubin-Johnson é uma patologia hepatobiliar rara, autossómica recessiva, caracterizada por hiperbilirubinémia conjugada, cuja origem está na ausência de uma proteína MRP2 funcional. Uma vez que as suas manifestações clínicas são pouco exuberantes e comuns a outras hiperbilirrubinémias hereditárias, o SDJ é uma entidade sobejamente subdiagnosticada. Contudo, estabelecer um diagnóstico correto é essencial para evitar a realização de procedimentos invasivos e gastos desnecessários.
Com o estudo deste caso, pretende-se desenvolver uma revisão detalhada do síndrome de Dubin-Jonhson, com particular destaque no diagnóstico. Com esta revisão pretendemos justificar o diagnóstico de SDJ mesmo com um teste genético não conclusivo e com achados atípicos como a elevada cuprúria.
A 42-year-old man with no relevant past medical history presents chronic mild icterus, fatigue, and no signs of chronic liver disease. Laboratory tests were remarkable for normal liver tests except hyperbilirubinemia (total bilirubin 7.76 mg/dL, direct bilirubin 5.50 mg/dL), increased urinary copper (2.44 mol/24 hours), and increased urinary coproporphyrin I (86% of the total urinary coproporphyrin output). Genetic analysis found the mutation NM_000392.5:c.1483A>G on MRP2 gene, in heterozygous state. Clinical diagnosis of Dubin-Johnson syndrome (DJS) was assumed. DJS is a rare autosomal recessive liver disease characterized by chronic conjugated hyperbilirubinemia, caused by the absence of hepatic functional MRP2 protein. Due to its mild symptoms that overlap with other hereditary hyperbilirubinemias, DJS is highly underdiagnosed. However, establishing DJS diagnosis is crucial to reassure the patient and avoid unnecessary invasive and costly diagnostic procedures. We present a comprehensive review of DJS, with special focus on its diagnosis. With this review we aim to justify the diagnosis of DJS for the presented patient, regardless of the genetic test and confounders such as high cupruria.
A 42-year-old man with no relevant past medical history presents chronic mild icterus, fatigue, and no signs of chronic liver disease. Laboratory tests were remarkable for normal liver tests except hyperbilirubinemia (total bilirubin 7.76 mg/dL, direct bilirubin 5.50 mg/dL), increased urinary copper (2.44 mol/24 hours), and increased urinary coproporphyrin I (86% of the total urinary coproporphyrin output). Genetic analysis found the mutation NM_000392.5:c.1483A>G on MRP2 gene, in heterozygous state. Clinical diagnosis of Dubin-Johnson syndrome (DJS) was assumed. DJS is a rare autosomal recessive liver disease characterized by chronic conjugated hyperbilirubinemia, caused by the absence of hepatic functional MRP2 protein. Due to its mild symptoms that overlap with other hereditary hyperbilirubinemias, DJS is highly underdiagnosed. However, establishing DJS diagnosis is crucial to reassure the patient and avoid unnecessary invasive and costly diagnostic procedures. We present a comprehensive review of DJS, with special focus on its diagnosis. With this review we aim to justify the diagnosis of DJS for the presented patient, regardless of the genetic test and confounders such as high cupruria.
Descrição
Trabalho Final do Curso de Mestrado Integrado em Medicina, Faculdade de Medicina, Universidade de Lisboa, 2021
Palavras-chave
Síndrome Dubin-Jonhson Hiperbilirubinémia conjugada Proteína MRP2/cMOAT Gastroenterologia