Aldh1a2 mutations in Tetralogy of Fallot: evolutionary conservation of affected amino acids. A) The T to C transition at nucleotide 470 changes an ATT cistron into ACT, leading to the substitution of an Isoleucine at position 157 by a Threonine. The p.Ile157Thr was traced back to a maternal allele. B: The G to T transversion at nucleotide 451 changes a GCA cistron into TCA, leading to the substitution of an Alanine at position 151 by a Serine. The p.Ala151Ser mutation was traced back to a paternal allele. Interestingly, one paternal allele and one maternal allele both display an A to G transition at nucleotide 453, producing the p.Ala151Ala silent mutation (rs16939660). C) An alignment representing vertebrate Aldh1a1-3 (all-trans and 9-cis retinaldehyde dehydrogenases), the closely related ALDH2 s and ALDH1B1 s, as well as Aldh1Ls (Tetrahydrofolate Dehydrogenases) and ALDH8 s (9-cis retinaldehyde dehydrogenases) as outgroups. The alignment indicates that Ala151 (dark shading) is highly conserved in all ALDHs represented, while Ile157 is conserved in all vertebrate ALDH1As (light shading). Numbers displayed in the phylogenetic tree represent bootstrap support for the nodes represented.