Definition A disorder (OMIM:216360) characterised by the acronym COACH:
• Cerebellar vermis hypo/aplasia
• congenital Ataxia
• ocular Coloboma
• Hepatic fibrosis
Clinical findings Mental retardation, ataxia due to cerebellar hypoplasia, hepatic fibrosis and often, coloboma and renal cysts.
Imaging Patients demonstrate the molar tooth sign, a midbrain-hindbrain malformation classically associated with Joubert syndrome.
Molecular pathology Defects of
• CC2D2A, which encodes a protein required for ciliogenesis and sonic hedgehog/SHH signaling,
• RPGRIP1L, which encodes a protein that may be involved in apoptosis, craniofacial development, patterning of limbs, and formation of the left-right axis,
• TMEM67, which encodes meckelin, a major ciliary protein
all cause COACH syndrome
Synonym Joubert syndrome with congenital hepatic fibrosis