From MedlinePlus Genetics
Some people with CLN6 disease do not show signs or symptoms of the condition until adulthood, typically after age 30. These individuals can have epilepsy, ataxia, dysarthria, and a progressive loss of intellectual function. CLN6 disease usually does not cause vision loss in affected adults. Adults with this condition do not often survive more than 10 years after diagnosis.

CLN6 disease is one of a group of disorders known as neuronal ceroid lipofuscinoses (NCLs), which may also be collectively referred to as Batten disease. All these disorders affect the nervous system and typically cause worsening problems with vision, movement, and thinking ability. The different NCLs are distinguished by their genetic cause. Each disease type is given the designation "CLN," meaning ceroid lipofuscinosis, neuronal, and then a number to indicate its subtype.

Most children with CLN6 disease initially experience the loss of previously acquired skills (developmental regression). Affected individuals can also develop recurrent seizures (epilepsy), difficulty coordinating movements (ataxia), muscle twitches (myoclonus), impaired speech (dysarthria), and vision loss. The movement problems worsen over time until affected children cannot walk, stand, or sit without assistance. Intellectual function also declines over time. Most children with CLN6 disease do not survive into adulthood.

CLN6 disease is an inherited disorder that primarily affects the nervous system. The signs and symptoms of this condition typically begin between early and late childhood, but sometimes they can appear in adulthood.  https://medlineplus.gov/genetics/condition/cln6-disease