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Table 1 Mutations affecting amnion formation

From: Amnion formation in the mouse embryo: the single amniochorionic fold model

Gene Gene Product Phenotype Onset Phenotype Lethality Reference
Amn Type I transmembrane protein Amnion absent while extraembryonic structures like chorion, yolk sac blood islands, and allantois develop normally E 6.5 - Prestreak, no amniotic fold E 9.5 [33, 48, 49]
Bmp1/Procollagen C-proteinase Growth factor/protease Amnion present but lacks the fold covering the loops of the gut in the umbilical ring region E 11.5 Perinatal [6]
Bmp2 Growth factor Amnion has a delayed fusion or fails to fuse; heart is formed within the exocoelomic cavity as a result of lack of amnion fusion E 7.0 - Late streak, large exocoelomic cavity E8.5 to E9.5 [34]
Ds (Ds mutation) Not known Semidominant mutation associated with early amnion rupture or amniotic band sequence (ABS) E 18.5 Viable [58, 59]
Evi1 Transcription factor with zinc finger motifs Amnion filled with fluid; unbalanced amniotic ectoderm and mesoderm E 7.5 - Neural plate, amnion and chorion segregated E10.5 [60]
Fibronectin High molecular-weight glycoprotein Undersized amnion; amniotic cavity with pressure deficit E 7.5 - Neural plate, amnion and chorion segregated E9.5 to E10.5 [4]
FoxF1 Winged helix transcription
Factor
Undersized amnion tightens and restricts embryo growth; ectopic VCAM and receptor α1-integrin expression in amniotic mesoderm E 7.5 - Neural plate, amnion and chorion segregated E9.5 to E10.5 [44]
Ldb1 LIM domain-binding protein Undersized amnion leading to constricted embryonic-extraembryonic junction E 7.5 - Neural plate, amnion and chorion segregated E9.5 to E10 [61]
Paxillin Focal adhesion molecule Undersized amnion; amniotic cavity with pressure deficit E 7.5 - Neural plate, amnion and chorion segregated E8.5 to E9 [62]
Smad5 Bmp signaling intermediate Delayed fusion of the amnion; Thickenings containing ectopic haematopoietic, endothelial and PGC-like cells E 7.0 - Late streak/early bud, amnion fusion E9.5 to E10.5 [31, 32, 50]
*Flk1 VEGF Receptor In chimeras, Flk1 null cells fail to form blood islands and accumulate in amnion E 7.5 - Neural plate, chorion and ectoplacental cone fuse E9.5 [63]
*Gastrulation mutants not applicable No mesoderm and amniochorionic fold forms, and consequently no amnion E 6.5 - Prestreak, no amniotic fold E7.5 [64]
  1. * The observed amnion defects are considered secondary.