The Diagnostic Saga of a Rare Congenital Bile Acid Synthesis Disorder: A Case Report

Abstract

Congenital bile acid synthesis disorder type 1 is an extremely rare disease with around 100 cases identified worldwide. Diagnosis remains challenging for pediatricians in view of the non-specific, variable clinical presentations of cholestasis, fat malabsorption, and liver cirrhosis. Early diagnosis and therapy with cholic acid are crucial to reverse the hepatopathy and prevent fatal outcomes. This paper sheds light on the diagnostic challenges of congenital bile acid synthesis disorder type 1 in a patient with an unusual presentation and a previously unreported mutation in the HSD3B7 gene. Moreover, this report aims to increase awareness of this treatable disorder among pediatricians. A 4-year-old child presented to our Medical Center with splenomegaly, fever, multiple lymphadenopathies, and mild cholestasis without hepatomegaly. History was remarkable for recurrent infections since the age of 3 years. Differential diagnosis included viral infections, malignancies, and inherited metabolic disorders. After an extensive negative work-up, genetic testing by next-generation sequencing identified a previously unreported homozygous disease-causing variant in the HSD3B7 gene, confirming the diagnosis of congenital bile acid synthesis disorder type 1. Suggestive abnormal urinary bile acids metabolites were also identified. Bile acid replacement therapy was initiated with reversal of cholestasis. This case highlights an unusual phenotypic presentation and the diagnostic challenges of an extremely rare disorder of bile acid synthesis. An increased awareness among pediatricians and the use of next-generation sequencing as a first-tier test in the setting of non-specific clinical presentations may shortcut the list of extensive investigations, allowing an early diagnosis of such treatable disorders, thus improving the patients' outcomes.

Keywords: HSD3B7 gene; bile acid synthesis disorder; case report; cholic acid; exome sequencing.

Figure 1.

Bile acids synthesis pathway: 3-5-hydroxy-C27-steroid oxidoreductase enzyme deficiency.

Figure 2.

Computed tomography scan of abdomen and pelvis, coronal view: splenomegaly with normal liver size.

Figure 3.

Liver elastography (Fibroscan): severe fibrosis, F3 score.