Treacher Collins syndrome

Treacher Collins syndrome (TCS) is a rare congenital birth disorder characterized by severe craniofacial defects. Autosomal dominant TCS1 and TCS2 are caused by mutations in the TCOF1 and POLR1D genes, respectively. Autosomal recessive TCS3 is caused by mutations in the POLR1C gene. The majority of TCS cases are caused by a mutation in TCOF1 gene which encodes a putative nucleolar phosphoprotein known as treacle. It has suggested that treacle is involved in the production of ribosomal RNA within cells. POLR1C and POLR1D encode subunits present in RNA polymerase I and III. Both of these polymerases are involved in ribosomal RNA transcription.