COACH syndromeCerebellar vermis hypo/aplasia, Oligophrenia, congenital Ataxia, ocular Coloboma, and Hepatic fibrosis syndrome. A disorder (OMIM:216360) characterised by mental retardation, ataxia due to cerebellar hypoplasia, hepatic fibrosis and often, coloboma and renal cysts.
Patients demonstrate molar tooth sign, a midbrain-hindbrain malformation classically associated with Joubert syndrome.
Caused by defects of:
• CC2D2A, which encodes a protein required for ciliogenesis and sonic hedgehog/SHH signalling;
• RPGRIP1L, which encodes a protein that may be involved in apoptosis, craniofacial development, patterning of limbs and formation of the left-right axis; and
• TMEM67, which encodes meckelin, a key ciliary protein.