Table 4

Mutant nameGene mutatedFunction of proteinPossible mechanism of NTD
Schematic
representations of ectopic spinal neural tube
Rate of
occurrence
of spina bifida
Phenotype and reference

Fibroblast growth factor receptor 1
(knockout producing chimeras)
Fgfr1Growth factor receptorUnknown (NTDs occur only in chimaeras)E10.5, 29.5% have spina bifida and 15% have ectopic neural tubeSpina bifida, second NT; NT in NT & kinky tail [94]

Tumour necrosis factor receptor associated factor 4
(knockout)
Traf4Intracellular signaling adaptorUnknownNo ectopic neural tube40% homozygous nulls have spina bifidaSpina bifida [95]

Shp2
(knockout producing chimeras)
Shp2Tyrosine phosphatase
(dephosphorylates proteins)
Unknown (NTDs occur only in chimaeras)E10.5, 36% of high content chimeras have second neural tube and 59% have spina bifida
Spina bifida, second NT [96]

Axial defects
(spontaneous mutant; gene not identified)
NDNDNDNo ectopic neural tube
10% penetrance in CD1
Spina bifida [97]

Glial cells missing-1
(knockout)
Gcm1Transcription factor
Ectopic expression causes NTDs by unknown mechanism25.8% transgenics have spina bifida; 100% transgenics have ectopic neural tubeSpina bifida; multiple NT [98]

Vacuolated lens
(spontaneous mutant)
ND
ND
Suggested failure in apposition and fusion?50% of homozygous nulls show spina bifida at 12 dpcSpina bifida [99]

PAK4
(knockout)
PAK4Cytoskeletal organizationTarget for Rho GTPase Cdc42
NoneDouble neural tube with one notochord
No spina bifida
[100]

EphA2
(knockout)
EphA2Adhesion and fusion?Receptor tyrosine kinase
NoneKinky tail with double neural tube
No spina bifida
[101]

WASP
(knockout)
WASPCytoskeletal organizationFormation of cell-surface projections (filopodia) required for cell movement and actin-based motility
NoneWavy neural tube
No spina bifida
[102]

Vinculin
(knockout)
(E10 Lethal)
VinculinCytoskeletal organizationMajor constituent of cell junctions (cell matrix & cell-cell)None
Wavy neural tube
No spina bifida
[103]