Consequences of JAG1 mutations.
BACKGROUND
Alagille syndrome (AGS) is a multi-system, autosomal dominant disorder with highly variable expressivity, caused by mutations within the Jagged1 (JAG1) gene.


METHODS
We studied 53 mutation positive relatives of 34 AGS probands to ascertain the frequency of clinical findings in JAG1 mutation carriers.


RESULTS
Eleven of 53 (21%) mutation positive relatives had clinical features that would have led to a diagnosis of AGS. Seventeen of the 53 (32%) relatives had mild features of AGS, revealed only after targeted evaluation following the diagnosis of a proband in their family. Twenty five of the 53 (47%) mutation positive relatives did not meet clinical criteria, and two of these individuals had no features consistent with AGS at all. The frequency of cardiac and liver disease was notably lower in the relatives than in the probands, characterising the milder end of the phenotypic spectrum. The characteristic facies of AGS was the feature with the highest penetrance, occurring almost universally in mutation positive probands and relatives.


CONCLUSIONS
This study has implications for genetic counselling of families with AGS and JAG1 mutations.
Kamath
B M
BM
Division of Gastroenterology, The Children's Hospital of Philadelphia, The University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.
Bason
L
L
Piccoli
D A
DA
Krantz
I D
ID
Spinner
N B
NB
D000293:Adolescent; D000328:Adult; D000368:Aged; D016738:Alagille Syndrome / Q000175:diagnosis* / Q000235:genetics*; D002135:Calcium-Binding Proteins; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D000072100:Jagged-1 Protein; D008297:Male; D008565:Membrane Proteins; D008875:Middle Aged; D009154:Mutation; 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