Heterozygous mutations of ATP8B1, ABCB11 and ABCB4 cause mild forms of Progressive Familial Intrahepatic Cholestasis in a pediatric cohort / Mutaciones en heterocigosis en ATP8B1, ACB11 y ABCB4 como causa de formas leves de Colestasis Intrahepática Progresiva Familiar en una cohorte pediátrica

Introduction: Heterozygous defects in genes implicated in Progressive Familial Intrahepatic Cholestasis have been described in milder forms of cholestatic diseases. Our aim is to describe clinical, laboratory and imaging characteristics as well as treatment and outcome of a cohort of pediatric patients with heterozygous mutations in ATP8B1, ABCB11 or ABCB4. Patients and methods: We present a retrospective descriptive study including pediatric patients with at least one heterozygosis defect in ATP8B1, ABCB11 or ABCB4 diagnosed after a cholestatic episode. Clinical, diagnostic and outcome data were collected including gene analysis (panel of PFIC NextGeneDx®). Results: 7 patients showed a heterozygous mutation: 3 patients in ABCB4, 1 in ABCB11, 2 in ABCB4 and ABCB11 and 1 in ATP8B1. The median onset age was 5.5 years with a median time of follow-up of 6 years. The initial presentation was pruritus followed by asymptomatic hypertransaminasemia and persistent cholestasis. Two patients had family history of gallbladder stones and mild hepatitis. All showed elevated transaminases and bile acids, high gamma glutamyl-transferase (GGT) in 3 and conjugated bilirubin in 2 patients. Liver biopsy showed inflammatory infiltrate or mild fibrosis with normal immunohistochemistry. All patients were treated with ursodeoxycholic acid, two patients requiring the addition of resincholestyramine. During follow-up, 3 patients suffered limited relapses of pruritus. No disease progression was observed. Conclusion: Heterozygous mutations in genes coding proteins of the hepatocellular transport system can cause cholestatic diseases with great phenotypic variability. The presence of repeated episodes of hypertransaminasemia or cholestasis after a trigger should force us to rule out the presence of these heterozygous mutations in genes involved in CIFP.(AU)

Introducción: Se han descrito defectos en los genes implicados en las colestasis intrahepáticas familiares progresivas (CIFP) causantes de colestasis más leves. El objetivo es estudiar las manifestaciones clínicas, analíticas y de imagen así como la evolución y respuesta al tratamiento de los portadores en heterocigosis de mutaciones en ATP8B1, ABCB11 y ABCB4. Pacientes y métodos: Estudio descriptivo retrospectivo de pacientes con al menos una mutación en heterocigosis en los genes ATP8B1, ABCB11 o ABCB4 diagnosticados tras un episodio de colestasis. Se recogieron variables demográficas y datos clínicos, diagnósticos, incluyendo estudio genético (panel de CIFP NextGeneDx®), tratamiento y evolución. Resultados: 7 pacientes presentaron al menos una mutación en heterocigosis: 3 en ABCB4, 1 en ABCB11, 2 en ABCB4 y ABCB11 y 1 en ATP8B1. La edad media de inicio fue de 5.5 años con un tiempo medio de evolución de 6 años. La clínica inicial fue prurito seguida de hipertransaminasemia asintomática y colestasis persistente. Dos pacientes tenían antecedentes familiares de litiasis biliar y hepatitis leve. Todos mostraron transaminasas y ácidos biliares elevados, 3 gamma-glutamiltransferasa (GGT) y 2 bilirrubina directa. La biopsia hepática mostró infiltrado inflamatorio o fibrosis leve, inmunohistoquímica normal. Fueron tratados con ácido ursodeoxicólico añadiéndose colestiramina en 2. Durante el seguimiento 3 presentaron episodios autolimitados de prurito. No se observó progresión de la enfermedad. Conclusiones: Mutaciones en heterocigosis en los genes implicados en el sistema de transporte hepatocelular pueden ocasionar cuadros de colestasis con gran variabilidad fenotípica. Episodios repetidos de hipertransaminasemia o colestasis tras un desencadenante deben hacernos sospechar mutaciones en los genes implicados en las CIFP.(AU)

Heterozygous mutations of ATP8B1, ABCB11 and ABCB4 cause mild forms of Progressive Familial Intrahepatic Cholestasis in a pediatric cohort.

INTRODUCTION: Heterozygous defects in genes implicated in Progressive Familial Intrahepatic Cholestasis have been described in milder forms of cholestatic diseases. Our aim is to describe clinical, laboratory and imaging characteristics as well as treatment and outcome of a cohort of pediatric patients with heterozygous mutations in ATP8B1, ABCB11 or ABCB4. PATIENTS AND METHODS: We present a retrospective descriptive study including pediatric patients with at least one heterozygosis defect in ATP8B1, ABCB11 or ABCB4 diagnosed after a cholestatic episode. Clinical, diagnostic and outcome data were collected including gene analysis (panel of PFIC NextGeneDx®). RESULTS: 7 patients showed a heterozygous mutation: 3 patients in ABCB4, 1 in ABCB11, 2 in ABCB4 and ABCB11 and 1 in ATP8B1. The median onset age was 5.5 years with a median time of follow-up of 6 years. The initial presentation was pruritus followed by asymptomatic hypertransaminasemia and persistent cholestasis. Two patients had family history of gallbladder stones and mild hepatitis. All showed elevated transaminases and bile acids, high gamma glutamyl-transferase (GGT) in 3 and conjugated bilirubin in 2 patients. Liver biopsy showed inflammatory infiltrate or mild fibrosis with normal immunohistochemistry. All patients were treated with ursodeoxycholic acid, two patients requiring the addition of resincholestyramine. During follow-up, 3 patients suffered limited relapses of pruritus. No disease progression was observed. CONCLUSION: Heterozygous mutations in genes coding proteins of the hepatocellular transport system can cause cholestatic diseases with great phenotypic variability. The presence of repeated episodes of hypertransaminasemia or cholestasis after a trigger should force us to rule out the presence of these heterozygous mutations in genes involved in CIFP.