Table 1.

An overview of left-right patterning genes

				Mutant names and phenotypes
Gene	Species	Product/role	Stage/localization	Cilia phenotypes	Left-right phenotypes	PCP phenotypes	References
Nodal	Chick, mouse, frog, fish	TGFβ-family signaling molecule	Post-gastrulation, left-sided	Not known	Heterotaxia	Not known	(Collignon et al., 1996; Levin et al., 1995; Lohr et al., 1997; Rebagliati et al., 1998)
V-ATPase	Frog	Proton pump	Four cell, right-sided	Reduction in number and length of cilia	Heterotaxia	Not known	(Adams et al., 2006)
H/K-ATPase	Chick, frog, rabbit	Potassium/proton exchanger	Four cell, right-sided	Not known	Heterotaxia	Not known	(Hibino et al., 2006; Levin et al., 2002)
Left-right dynein (Lrd; Dnahc11)	Human, mouse, fish	Microtubule-based motor protein. Selectively segregates chromatids in mouse cells	Non-ciliated ES cells and blastocysts (mRNA); ciliated cells in adult mice, including node monocilia; Kupffer's vesicle in fish	Immotile cilia	50% situs inversus, 50% situs solitus	Not known	(Armakolas and Klar, 2007; Okada et al., 1999; Supp et al., 1997)
Inversin (Inv; Invs)	Human, mouse, frog	Inhibits canonical Wnt signaling	RNA in two-cell mouse embryo; localization includes basal bodies, cilia membranes, microtubules	No obvious morphologic al changes in cilia, slightly slower beating	Inv mouse mutants exhibit 100% situs inversus	Inv mutant mice exhibit hair pattern defects; in Xenopus, required for convergent extension	(Morgan et al., 1998; Simons et al., 2005)
Polaris (Ift88)	Mouse, fish	Intraflagellar transport	Cilia and basal bodies, centrosome	No central cilium in ventral node cells of mouse	Heterotaxia	In mice, misoriented cochlear stereociliary bundles	(Bisgrove et al., 2005; Murcia et al., 2000; Robert et al., 2007)
Nephrocystin 3 (Nphp3)	Human, mouse	Inhibits canonical Wnt signaling	Primary cilia, basal bodies, centrosomes	Longer renal monocilia	Situs inversus	Defects in convergent extension in Xenopus	(Bergmann et al., 2008)
BBS genes	Human, mouse	Intracellular trafficking, basal body and cilia formation and function	Centrosomes, centrioles, basal bodies, cilia	Shorter, fewer cilia	Heterotaxia	Misoriented cochlear stereociliary bundles, neural tube defects. Interacts genetically with Vangl2	(Ansley et al., 2003; Kim et al., 2004; Ross et al., 2005; Tobin and Beales, 2007; Yen et al., 2006)
Seahorse (Irrc6)	Fish	Inhibits canonical Wnt signaling	Cytoplasmic puncta in ciliated tissues	None	Heterotaxia	Defects in convergent extension in zebrafish gastrulation	(Kishimoto et al., 2008)

This overview is limited to the genes and proteins discussed in this article.

BBS, Bardet-Biedl syndrome.