In a 25 March 2021 interview, Marrero said that initial symptoms are often nonspecific, making a diagnosis challenging. He listed symptoms such as "behavioral changes, sleep disturbances, unexplained pain, visual hallucinations, coordination problems, unexplained hair loss, involuntary muscle twitching, formication (a sensation that feels like small insects crawling under the skin), ataxia, and brain atrophy". In April the NBPH website listed symptoms such as memory problems, muscle spasms, balance issues, difficulty walking or falls, blurred vision or visual hallucinations, unexplained or significant weight loss, behaviour changes and pain in the upper or lower limbs. In interviews conducted by the media, patients and their families described symptoms such as rapidly progressing dementia, unexplained and significant weight loss, myoclonus, aphasia, changes in behaviour, sleep disturbances, unexplained pain, visual hallucinations, co-ordination problems and severe muscle and brain atrophy, progressing over a period of 18 to 36 months. The majority experience multi-day insomnia even with "sleep medication". Memory loss and aphasia are seen. In some<unk> s, Capgras delusion and echolalia have been reported. Myoclonus persists "even in the late stages of the disease" and even "when patients are unconscious". Akinetic mutism were observed in late-stage patients, where they no longer have the ability to speak or move. The<unk>  York Times reported symptoms of "extreme fatigue, involuntary jerking movements, memory lapses and hallucinations" on 4 June 2021.
New Brunswick neurological syndrome of unknown cause
Acorea, microphthalmia and cataract syndrome
Autosomal dominant nocturnal frontal lobe epilepsy
Acute cerebellar ataxia of childhood
Northern epilepsy syndrome
Spinal muscular atrophy with progressive myoclonic epilepsy
Benign neonatal sleep myoclonus
Catel–Manzke syndrome