Unusual Cystic Fibrosis Transmembrane Conductance Regulator Mutations and Liver Disease: A Case Series and Review of the Literature.

Cystic fibrosis (CF) is caused by a mutation in the CF transmembrane conductance regulator (CFTR) gene, deranging the activity of chloride channels on the epithelial cell surface. Herein we describe end-stage liver disease in 3 infants with rare CFTR gene mutations; 2 of them were heterozygous. Case 1 was a premature male infant with negative CF screening at birth who developed a small bowel obstruction in the neonatal period requiring an ileostomy, with subsequent cholestatic liver disease and portal hypertension. In addition, he was noted to have frequent respiratory infections prompting a sweat test, which was positive. Genetic testing revealed that he was heterozygous for P.1177F. He then underwent a successful liver transplant. Case 2 was a female infant who developed progressive cholestasis with poor weight gain and was found to have neonatal hepatitis on liver biopsy. A sweat test was negative and genetic testing revealed she was heterozygous for CFTR and PEX26 gene mutations. She subsequently developed pneumatosis involving the cecum that was treated conservatively, followed by a successful liver transplant. Case 3 was a male infant who developed progressive liver disease, with liver biopsy showing neonatal hepatitis. He was extensively investigated but had a negative sweat test on repeated studies. Genetic testing revealed that the patient was heterozygous P.K186N-variant in the AKRID1 gene and homozygous P.R75Q-variant in the CFTR gene. Unfortunately, he succumbed to an acute upper gastrointestinal hemorrhage. Rare and unusual CFTR mutations, even in the heterozygous form, may be a feature in otherwise undiagnosed end-stage liver disease of infancy.