Patient 6 is a male who is currently 2 years 7 months old. He was observed to have severe hypotonia in his infancy and developmental delay. He was incapable of lifting his head at the age of 5 months but could sit independently at 9 months; however, he exhibited a regression in development and was unable to walk independently. He also did not show any non-verbal communication skills and was unable to imitate or babble. Poor eye contact, head shaking, hand clapping and hand wringing were observed at the age of 1 year and 6 months. The patient displayed purposeful hand usage. He also presented recurrent, febrile or non-febrile, generalized tonic-clonic seizures at the age of 9 months. Topiramate, VPA and LEV were used but none of them showed a positive effect; this treatment was withdrawn at the age of 2 years. At present, the patient's daily seizures have been characterized as myoclonic. EEG findings obtained at the age of 10 months revealed spike-slow waves with bilateral-central-frontal involvement. MRI scans taken at the age of 15 months showed developmental malformation of the corpus callosum ().
Patient 4 was a boy aged 7 years and 8 months. He achieved the gross motor developmental milestones somewhat delay, with rising head at 1 year old, sitting alone at 1 year and 2 months, and walking at 1.5 years. Lack of speech was another problem, that he still cannot speak a single word so far (7 years and 8 months). He was always immersed in his own world, showed little interest to the others, and lacked eye-contact. Febrile seizures attacked at 1 year, which turned into afebrile seizures at 2 years old. Partial seizures occurred 1~ 2 times per month, lasted few minutes to more than half an hour. The epilepsy was fever-sensitive. VPA was used at 2.5 years of age, and no seizures occurred after 4 years of age. EEG at 2.5 years displayed (multi-) spike and slow waves at right occipital region, with slow rhythm on the background. MRI at 3 years of age was normal. A novel mutation, c.403-1G > T, of MEF2C was identified, which arose de novo.