Global developmental delay is observed in children with NUBPL complex I deficiency. The disease typically affects a part of the brain called the cerebellum and cerebellar atrophy is often observed in brain MRIs but this may not show up until the child is older. Common symptoms are ataxia (such as inability to sit up, crawl, or walk unsupported), dysarthria (slowed and/or slurred speech), nystagmus (repetitive and rapid eye movements), tremor (such as in reaching for objects), and spasticity. Depending on the types of NUBPL mutations found, hypotonia (decreased muscle tone, such as the child feeling limp in your arms) is also observed.
NUBPL