FIG. 3.
Mutation of the NPXY1 motif causes fetal hepatomegaly and perinatal death. The majority of fetuses with inactivated NPXY1 motifs survive through pregnancy up to term but then die shortly before or immediately after birth. At E18.5 (shown here) fetuses with mutated NPXY1 motifs (B and D) are mildly disproportionate, with a foreshortened neck and caudal body region and an enlarged abdomen, compared to wild-type littermates (A and C). Upon dissection, the fetuses feature a drastically enlarged liver (compare panels C and D) but no further macroscopic abnormalities. Sagittal sections indicate that already at E16.5 the liver is markedly enlarged (arrows), partially displacing the gut in the caudal abdominal cavity. (E) Wild type. (F) NPXY1 mutation. (Note that positions of stomach in panels E and F [arrowheads] indicate comparable paramedian planes of sectioning.) No major abnormalities of other organs are evident.