Alagille syndrome (AGS) is an autosomal dominant disorder caused by mutations in 
Jagged1 (JAG1), a ligand in the evolutionarily conserved Notch signaling 
pathway. Previous studies have demonstrated that a wide spectrum of JAG1 
mutations result in AGS. These include total gene deletions, protein truncating, 
splicing and missense mutations which are distributed across the coding region 
of the gene. Here we present results of JAG1 mutation screening by SSCP and FISH 
in 105 patients with AGS. For these studies, new primers were designed for 12 
exons. Mutations were identified in 63/105 patients (60%). The spectrum of the 
JAG1 mutations presented here is consistent with previously reported results. 
Eighty three percent (52/63) of the mutations were protein truncating, 11% 
(7/63) were missense, 2% (1/63) were splice site, and 5% (3/63) were total gene 
deletions demonstrable by FISH. Six of the missense mutations are novel. As has 
been reported previously, there is no apparent relationship between genotype and 
clinical phenotype.