A TCTN2 mutation defines a novel Meckel Gruber syndrome locus

Meckel Gruber syndrome (MKS) is an autosomal recessive multisystem disorder that represents a severe form of ciliopathy in humans and is characterized by significant genetic heterogeneity. In this article, we describe the identification of a novel MKS locus MKS8 that we map to TCTN2, in a multiplex consanguineous family. TCTN2 is a paralog of the recently identified Tectonic 1, which has been shown to modulate sonic Hedgehog signaling. Expression analysis at different developmental stages of the murine ortholog revealed a spatial and temporal pattern consistent with the MKS phenotype observed in our patient. The exclusion of this and the other seven MKS genes in our collection of consanguineous Arab MKS families confirms the existence of two additional MKS loci.