COACH Syndrome

COACH syndrome, also known as Joubert syndrome with hepatic defect,[1] is a rare autosomal recessive genetic disease. The name is an acronym of the defining signs: cerebellar vermis aplasia, oligophrenia, congenital ataxia, coloboma and hepatic fibrosis. The condition is associated with moderate intellectual disability.[2] It falls under the category of a Joubart Syndrome-related disorder (JSRD)

Causes of COACH Syndrome #

• COACH syndrome is a genetic disease, which means that it is caused by one or more genes not working correctly.

• Disease causing variants in the following gene(s) are known to cause this disease: TMEM67, RPGRIP1L, CC2D2A, INPP5E

Symptoms of COACH Syndrome #

• Signs of COACH syndrome tend to present from birth to early childhood.

• Facial abnormalities are a common symptom, with some characteristics being broadness of the forehead, ptosis of either one or both eyes and misalignment of the eyes.

• Other cases also report a carp shaped mouth, flattened face and nose and hypertelorism.

• Patients are often within the lower percentiles for height and weight growth.

• Hypotonia is a possible sign of COACH syndrome.

• Infants with COACH syndrome may experience very categorical hyperventilation and complications with respiration, such as irregular breathing.

• It has been reported that as patients surpass infancy, these respiratory issues may disappear

Diagnosis of COACH Syndrome #

• The diagnosis of COACH syndrome is based on the presence of all five categories; cerebellar vermis hypoplasia, oligophrenia, congenital ataxia, coloboma, and hepatic fibrosis.

• Detection of the hypoplasia of the cerebellar vermis is achieved through a cranial magnetic resonance imaging (MRI) scan.

• The presence of the ‘molar tooth sign’ (MTS) on the MRI scan, a mid- brain hind- brain malformation, confirms this condition and is a key indicator of COACH syndrome.

• The MTS’s distinguished shape is attributed to the lengthened superior cerebellar peduncles and deepened interpeduncular fossa.

• To diagnose ataxia, both neurological assessment and physical examination are required.

• This can include MRI scans, study of behavior and motor skills in infancy and analysis of family history and genetics.

• In the case of congenital ataxia, patients are born with the condition and thus diagnosis is more difficult, therefore diagnosis of ataxia alone is not sufficient to indicate COACH syndrome, and must be used in conjunction with other symptoms.

• Oligophrenia, more commonly known as intellectual disability, is diagnosed using personalized testing to measure intelligence and physical examination for anomalies and facial dysmorphia.

• Hepatic fibrosis has a range of diagnostic techniques, including invasive and non- invasive.

• Liver biopsy examination is an invasive technique, which uses liver tissue extracted from the patient to identify the degree and severity of the fibrosis, and may also provide insight on tumor growth.

Treatment of COACH Syndrome #

• Management includes monitoring patients’ neurological activity, development patterns and renal and hepatic function annually.

• Programs for special education and occupational therapy for speech and motor impairment can improve symptoms of intellectual disability and quality of life for patients.

• Families and patients are offered ongoing psychological support and specialized care is provided to aid societal integration.

• In some cases, antiepileptic drugs or neuroleptics are prescribed to reduce anger and behavioral difficulties and improve mood.

• Some children with hypotonia and other motor skill complications may need a nasogastric feeding tube in order to ensure adequate nutrients are received and breathing is undisrupted.

• Ophthalmological surgery may be used to treat coloboma and ptosis of the eye to improve vision and appearance.

• A common technique to treat coloboma is intraocular lens (IOL) implantation, whereby a lens is surgically inserted and adhered to the iris to improve vision and appearance.

• In some severe cases, in conjunction with the IOL implantation, an artificial iris may be inserted into the lens capsule to treat this condition.

• To treat ptosis, upper eyelid blepharoplasty is used for both cosmetic and functional reasons.

• Excess muscle and fat is removed, and the lid is raised in this procedure, and it is considered a minor procedure.