In previous studies, we showed that the homozygous Zic1 null mutation (Zic1-/-) results in cerebellar malformation with severe ataxia and that holoprosencephaly and spina bifida occur in homozygotes for Zic2 knockdown mutation (Zic2kd/kd).
The study focused on the associated brain malformations, including neuronal migration defects, which predominated in individuals with ZIC2 mutations, and neural tube defects, which were frequently associated with ZIC2 (rachischisis) and TGIF mutations.
Because the Zic2 knockdown mouse is the first mutant with HPE and spina bifida to survive to the perinatal period, the mouse will promote analyses of not only the neurulation but also the pathogenesis of human HPE.
In previous studies, we showed that the homozygous Zic1 null mutation (Zic1-/-) results in cerebellar malformation with severe ataxia and that holoprosencephaly and spina bifida occur in homozygotes for Zic2 knockdown mutation (Zic2kd/kd).
Here we present a case study of a use of the distributed analytical environment integrating four complementary specialized resources, namely the Lynx platform, VISTA RViewer, the Developmental Brain Disorders Database (DBDB), and the RaptorX server, for the identification of high-confidence candidate genes contributing to pathogenesis of spina bifida.
Protein tyrosine kinase 7 (Ptk7) was shown to cause a very severe form of NTDs called craniorachischisis in a mouse model and genetically interacts with a core PCP member Vangl2 where double heterozygotes suffer from spina bifida.
We identified five novel missense variants in VANGL1, p.Ser83Leu, p.Phe153Ser, p.Arg181Gln, p.Leu202Phe and p.Ala404Ser, occurring in sporadic and familial cases of spinal dysraphisms.
The combined TSER,3'UTR (2/2,+/+) genotype showed a more than 4-fold increased risk for SB within this specific ethnic group (OR = 4.7 [1.1-19.8], p = 0.04).
Transmission disequilibrium of SNP alleles in cystathionine-beta-synthase, dihydrofolate reductase, methylenetetrahydrofolate reductase, and thymidylate synthetase confers an increased susceptibility to SB.
With respect to spina bifida, we observed ORs with 95% confidence intervals that did not include 1.0 for the following SNPs (heterozygous or homozygous) relative to the reference genotype: BHMT (rs3733890) OR = 1.8 (1.1-3.1), CBS (rs2851391) OR = 2.0 (1.2-3.1); CBS (rs234713) OR = 2.9 (1.3-6.7); MTHFD1 (rs2236224) OR = 1.7 (1.1-2.7); MTHFD1 (hcv11462908) OR = 0.2 (0-0.9); MTHFD2 (rs702465) OR = 0.6 (0.4-0.9); MTHFD2 (rs7571842) OR = 0.6 (0.4-0.9); MTHFR (rs1801133) OR = 2.0 (1.2-3.1); MTRR (rs162036) OR = 3.0 (1.5-5.9); MTRR (rs10380) OR = 3.4 (1.6-7.1); MTRR (rs1801394) OR = 0.7 (0.5-0.9); MTRR (rs9332) OR = 2.7 (1.3-5.3); TYMS (rs2847149) OR = 2.2 (1.4-3.5); TYMS (rs1001761) OR = 2.4 (1.5-3.8); and TYMS (rs502396) OR = 2.1 (1.3-3.3).
In brain tissue, levels of PAX3 were significantly reduced in both encephalocele and spina bifida subtypes; the expression levels of cleaved caspase 3(17 kD) of encephalocele cases and cleaved caspase 8(47/45 kD) in spina bifida cases were higher than in controls; no difference was found in the expression of p53 or caspase 9 between NTDs and controls.