Supplementary Figure 11: Pattern of loss of MMP21 from vertebrate genomes may correlate with absence of nodal cilia-generated asymmetry.
From: MMP21 is mutated in human heterotaxy and is required for normal left-right asymmetry in vertebrates
On the basis of the absence of evidence for an intact MMP21 ORF in the cetartiodactyl, bird and reptile clades and the previous suggestion that in chick and pig left-right asymmetry is generated not by leftward fluid flow but rather by rotational cell movements, we hypothesize that the presence of MMP21 correlates with the presence of cilia-driven and/or cilia-sensing nodal flow. The vertebrate phylogenetic tree is reproduced from the UCSC Genome Browser page “Vertebrate Multiz Alignment & Conservation (100 Species)," hg19 assembly.
