Inheritance from both parents will result in the disease
Age range at onset:
Neonatal or infancy
Specialists you may see:
Those severely affected by LTBL will develop symptoms soon after birth, including hypotonia, dystonia, spasticity and seizures. Development of mental and movement abilities is often delayed. High levels of lactate can cause an abnormal heartbeat and severe breathing problems. Some also experience liver failure.
Mildly affected children develop symptoms after the age of 6 months. Psychomotor regression, spasticity and extreme irritability are common, and some also experience seizures. After the age of 2, some mental and movement abilities are regained and the condition begins to improve. Those with more severe forms of LTBL may not improve and symptoms may become life-threatening.
Mutations in the EARS2 gene cause LTBL. The EARS2 gene creates an enzyme which contributes to protein production in the mitochondria. When the EARS2 gene is mutated, the amount of this enzyme is reduced, disrupting protein production. It is believed that this has an impact on production of energy within the mitochondria, but it is unclear how this specifically affects the brain.