Table 4

Mutant nameGene mutatedFunction of proteinPossible mechanism of NTD
representations of ectopic spinal neural tube
Rate of
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
Traf4Intracellular signaling adaptorUnknownNo ectopic neural tube40% homozygous nulls have spina bifidaSpina bifida [95]

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

PAK4Cytoskeletal organizationTarget for Rho GTPase Cdc42
NoneDouble neural tube with one notochord
No spina bifida

EphA2Adhesion and fusion?Receptor tyrosine kinase
NoneKinky tail with double neural tube
No spina bifida

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

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