Eight individuals with rare heterozygous missense FRMD5 variants who present with neurodevelopmental disorders were initially reported. All probands exhibit developmental delay including motor delay. All probands present with intellectual disability, except one proband who is too young to be diagnosed. Seven probands have ataxia. They all exhibit abnormalities of eye movement. Among them, four have nystagmus, whereas three have opsoclonus. One has strabismus, and one intermittent esotropia. Nystagmus and opsoclonus are abnormal involuntary eye movements, whereas strabismus is an abnormal conjugate eye movement. Six individuals have seizures or abnormal EEGs. Some individuals have refractory seizures. Three of the eight individuals have abnormal brain MRIs.
FRMD5