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.
Patient 3 is a 23-month-old girl who presented with RTT-like features. Feeding difficulties caused concern at 3 months of age. No epilepsy was observed, though she had medical history of febrile convulsions at 9 months old. There was significant delay in her developmental milestones, without obvious retrogression. She could sit alone at 1 year old, and walk at 23 months of age, with abnormal gaits. Unmeaningful language began at 12 months. She also presented with poor eye contact, stereotypic actions, breathing disturbance, and sleeping abnormalities. She suffered from recurrent respiratory infections frequently after 15 months of age. MRI revealed hypomyelination at 1 year and 10 months of age. A novel nonsense mutation, c.334G > T, p.Glu112*, in MEF2C was identified.