ALDH1A2 (RALDH2) genetic variation in human congenital heart disease.
BACKGROUND
Signaling by the vitamin A-derived morphogen retinoic acid (RA) is required at multiple steps of cardiac development. Since conversion of retinaldehyde to RA by retinaldehyde dehydrogenase type II (ALDH1A2, a.k.a RALDH2) is critical for cardiac development, we screened patients with congenital heart disease (CHDs) for genetic variation at the ALDH1A2 locus.


METHODS
One-hundred and thirty-three CHD patients were screened for genetic variation at the ALDH1A2 locus through bi-directional sequencing. In addition, six SNPs (rs2704188, rs1441815, rs3784259, rs1530293, rs1899430) at the same locus were studied using a TDT-based association approach in 101 CHD trios. Observed mutations were modeled through molecular mechanics (MM) simulations using the AMBER 9 package, Sander and Pmemd programs. Sequence conservation of observed mutations was evaluated through phylogenetic tree construction from ungapped alignments containing ALDH8 s, ALDH1Ls, ALDH1 s and ALDH2 s. Trees were generated by the Neighbor Joining method. Variations potentially affecting splicing mechanisms were cloned and functional assays were designed to test splicing alterations using the pSPL3 splicing assay.


RESULTS
We describe in Tetralogy of Fallot (TOF) the mutations Ala151Ser and Ile157Thr that change non-polar to polar residues at exon 4. Exon 4 encodes part of the highly-conserved tetramerization domain, a structural motif required for ALDH oligomerization. Molecular mechanics simulation studies of the two mutations indicate that they hinder tetramerization. We determined that the SNP rs16939660, previously associated with spina bifida and observed in patients with TOF, does not affect splicing. Moreover, association studies performed with classical models and with the transmission disequilibrium test (TDT) design using single marker genotype, or haplotype information do not show differences between cases and controls.


CONCLUSIONS
In summary, our screen indicates that ALDH1A2 genetic variation is present in TOF patients, suggesting a possible causal role for this gene in rare cases of human CHD, but does not support the hypothesis that variation at the ALDH1A2 locus is a significant modifier of the risk for CHD in humans.
Pavan
Marilene
M
InCor - HC FMUSP, São Paulo, Brasil. mari.pavan@gmail.com
Ruiz
Viviane F
VF
Silva
Fábio A
FA
Sobreira
Tiago J
TJ
Cravo
Roberta M
RM
Vasconcelos
Michelle
M
Marques
Lívia P
LP
Mesquita
Sonia M F
SM
Krieger
José E
JE
Lopes
Antônio A B
AA
Oliveira
Paulo S
PS
Pereira
Alexandre C
AC
Xavier-Neto
José
J
D000080924:Aldehyde Dehydrogenase 1 Family; D002460:Cell Line; D002884:Chromosomes, Human, Pair 15; D005091:Exons; D020022:Genetic Predisposition to Disease; D014644:Genetic Variation; D055106:Genome-Wide Association Study; D006330:Heart Defects, Congenital / Q000235:genetics*; D006801:Humans; D015810:Linkage Disequilibrium; D009154:Mutation; D016133:Polymerase Chain Reaction; D020641:Polymorphism, Single Nucleotide; D017510:Protein Folding; D050697:Retinal Dehydrogenase / Q000235:genetics; D013771:Tetralogy of Fallot / Q000235:genetics
D000080924:Aldehyde Dehydrogenase 1 Family; C545372:ALDH1A2 protein, human; D050697:Retinal Dehydrogenase