Mutations in JAGGED1 gene are predominantly sporadic in Alagille syndrome.
OBJECTIVE
Mutations in the JAGGED1 gene are responsible for the Alagille syndrome, an autosomal dominant disorder characterized by neonatal jaundice, intrahepatic cholestasis, and developmental disorders affecting the liver, heart, vertebrae, eyes, and face. We screened a large group of patients for mutations in JAGGED1 and studied transmission of the mutations.


METHODS
The coding sequence of the JAGGED1 gene was searched by single-strand conformation polymorphism and sequence analysis for mutations in 109 unrelated patients with the Alagille syndrome and their family if available.


RESULTS
Sixty-nine patients (63%) had intragenic mutations, including 14 nonsense mutations, 31 frameshifts, 11 splice site mutations, and 13 missense mutations. We identified 59 different types of mutation of which 54 were previously undescribed; 8 were observed more than once. Mutations were de novo in 40 of 57 probands.


CONCLUSIONS
Most of the observed mutations other than the missense mutations in JAGGED1 are expected to give rise to truncated and unanchored proteins. All mutations mapped to the extracellular domain of the protein, and there appeared to be regional hot spots, although no clustering was observed. Thus, the sequencing of 7 exons of JAGGED1 would detect 51% of the mutations. Transmission analysis showed a high frequency of sporadic cases (70%).
Crosnier
C
C
INSERM Unité 347 affiliée au Centre National de la Recherche Scientifique, Département de Pédiatrie, Hôpital de Bicêtre, Le Kremlin-Bicêtre, France.
Driancourt
C
C
Raynaud
N
N
Dhorne-Pollet
S
S
Pollet
N
N
Bernard
O
O
Hadchouel
M
M
Meunier-Rotival
M
M
D016738:Alagille Syndrome / Q000235:genetics*; D002135:Calcium-Binding Proteins; D004252:DNA Mutational Analysis; D005260:Female; D005787:Gene Frequency; D005820:Genetic Testing; D005838:Genotype; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D000072100:Jagged-1 Protein; D008297:Male; D008565:Membrane Proteins; D009154:Mutation; D010641:Phenotype; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D018807:Polymorphism, Single-Stranded Conformational; D011506:Proteins / Q000235:genetics*; D000072099:Serrate-Jagged Proteins
D002135:Calcium-Binding Proteins; D036341:Intercellular Signaling Peptides and Proteins; C000606273:JAG1 protein, human; D000072100:Jagged-1 Protein; D008565:Membrane Proteins; D011506:Proteins; D000072099:Serrate-Jagged Proteins