Question: What is (are) COACH syndrome ?
Answer: COACH syndrome is a condition that mainly affects the brain and liver. Most individuals with COACH syndrome have mental retardation, liver problems (fibrosis), and difficulty with movement (ataxia). Some may also have an abnormality of the eye (called a coloboma) or abnormal eye movements (such as nystagmus). This condition is inherited in an autosomal recessive manner; 70% of cases are thought to be caused by mutations in the TMEM67 gene. COACH syndrome is considered a rare form of another condition, Joubert syndrome.
Source: GARD

Question: What are the symptoms of COACH syndrome ?
Answer: What are the signs and symptoms of COACH syndrome? The Human Phenotype Ontology provides the following list of signs and symptoms for COACH syndrome. If the information is available, the table below includes how often the symptom is seen in people with this condition. You can use the MedlinePlus Medical Dictionary to look up the definitions for these medical terms. Signs and Symptoms Approximate number of patients (when available) Aplasia/Hypoplasia of the cerebellum 90% Apnea 90% Biliary tract abnormality 90% Cognitive impairment 90% Congenital hepatic fibrosis 90% Elevated hepatic transaminases 90% Hepatomegaly 90% Incoordination 90% Muscular hypotonia 90% Oculomotor apraxia 90% Chorioretinal coloboma 50% Feeding difficulties in infancy 50% Gait disturbance 50% Hyperreflexia 50% Iris coloboma 50% Long face 50% Narrow forehead 50% Nephropathy 50% Nystagmus 50% Optic nerve coloboma 50% Visual impairment 50% Abnormality of neuronal migration 7.5% Abnormality of the hypothalamus-pituitary axis 7.5% Abnormality of the oral cavity 7.5% Anteverted nares 7.5% Aplasia/Hypoplasia of the corpus callosum 7.5% Chronic hepatic failure 7.5% Cirrhosis 7.5% Encephalocele 7.5% Hernia of the abdominal wall 7.5% Highly arched eyebrow 7.5% Hydrocephalus 7.5% Low-set, posteriorly rotated ears 7.5% Macrocephaly 7.5% Multicystic kidney dysplasia 7.5% Neoplasm of the liver 7.5% Oral cleft 7.5% Portal hypertension 7.5% Postaxial hand polydactyly 7.5% Prominent nasal bridge 7.5% Ptosis 7.5% Renal insufficiency 7.5% Scoliosis 7.5% Seizures 7.5% Splenomegaly 7.5% Strabismus 7.5% Tremor 7.5% Ataxia - Autosomal recessive inheritance - Cerebellar vermis hypoplasia - Coloboma - Growth delay - Hepatic fibrosis - Heterogeneous - Hypertelorism - Infantile onset - Intellectual disability, moderate - Molar tooth sign on MRI - Multiple small medullary renal cysts - Nephronophthisis - Occipital encephalocele - Round face - Spasticity - Wide mouth - The Human Phenotype Ontology (HPO) has collected information on how often a sign or symptom occurs in a condition. Much of this information comes from Orphanet, a European rare disease database. The frequency of a sign or symptom is usually listed as a rough estimate of the percentage of patients who have that feature. The frequency may also be listed as a fraction. The first number of the fraction is how many people had the symptom, and the second number is the total number of people who were examined in one study. For example, a frequency of 25/25 means that in a study of 25 people all patients were found to have that symptom. Because these frequencies are based on a specific study, the fractions may be different if another group of patients are examined. Sometimes, no information on frequency is available. In these cases, the sign or symptom may be rare or common.
Source: GARD

Question: How to diagnose COACH syndrome ?
Answer: How is COACH syndrome diagnosed? While there are no official guidelines, a diagnosis of COACH syndrome can be made when an individual is found to have both a particular malformation of the brain called cerebellar vermis hypoplasia (also referred to as the "molar tooth sign" due to the characteristic look of this malformation on brain imaging) and liver disease (specifically fibrosis).
Source: GARD