Neuronal ceroid lipofuscinosis 5 (CLN5-NCL) is a rare condition that affects the nervous system. Signs and symptoms of the condition generally develop between ages 4.5 and 7 years, although later onset cases have been reported. Affected people may experience loss of muscle coordination (ataxia), seizures that do not respond to medications, muscle twitches (myoclonus), visual impairment, and cognitive/motor decline. It occurs predominantly in the Finnish population. CLN5-NCL is caused by changes (mutations) in the CLN5 gene and is inherited in an autosomal recessive manner. Treatment options are limited to therapies that can help relieve some of the symptoms.