From MedlinePlus Genetics
CLN4 disease is a condition that primarily affects the nervous system, causing problems with movement and intellectual function that worsen over time. The signs and symptoms of CLN4 disease typically appear around age 30, but they can develop anytime between adolescence and late adulthood.

People with CLN4 disease often develop seizures and uncontrollable muscle jerks (myoclonic epilepsy), a decline in intellectual function (dementia), problems with coordination and balance (ataxia), tremors or other involuntary movements (motor tics), and speech difficulties (dysarthria). The signs and symptoms of CLN4 disease worsen over time, and affected individuals usually survive about 15 years after the disorder begins.

CLN4 disease is one of a group of disorders known as neuronal ceroid lipofuscinoses (NCLs), which may also be collectively referred to as Batten disease. (The adult forms of NCLs, which includes CLN4 disease, are sometimes known as Kufs disease.) All the NCLs 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.  https://medlineplus.gov/genetics/condition/cln4-disease