Historically, diagnosis of progressive familial intrahepatic cholestasis (PFIC) has been based on a combination of clinical and laboratory or biochemical approaches. More recently, however, genetic testing has become the gold standard.2 In fact, genetic testing is the only reliable way to distinguish between PFIC1 and PFIC2.3
Genetic testing involves DNA sequencing of the 27 coding exons and their splice junctions. A resequencing chip that is dedicated to look for genetic syndromes of cholestasis has been developed and may facilitate diagnosis.1
Given that no phenotypic features can exclude PFIC1 or PFIC2 in a patient with normal GGT PFIC, immunohistochemistry with BSEP staining followed by genetic analysis is recommended. In patients with negative BSEP staining, one should ﬁrst test for ABCB11, whereas in patients with normal BSEP staining, ATB8B1 mutation should be looked for.1
Mirum is proud to sponsor free genetic testing through Travere Therapeutics to help with early diagnosis.