Patient 2 is a 2.5 years old girl presented with RTT-like ID. she displayed profound psychomotor retardation, with controlling head at 5 months, sitting alone at 8 months. She remained unable to walk independently and still had no speech at 2.5 years old. She developed stereotypic hand movements and bruxism at 2 years of age. No seizure was reported, but there was epileptiform discharge on EEG at age of 2 years. Brain MRI revealed high T1 and T2 signal at posterior horn of bilateral ventricle. A nonsense mutation, c.565C > T, p.Arg189*, of MEF2C was discovered, a known disease causing mutation ().
Patient 4 is a female who is currently 2 years 10 months old. Developmental delay was observed with regard to lifting of her head only at the age of 7 months and the ability to sit independently only at the age of 1 year; she also did not have the ability to walk independently and did not display any non-verbal communication skills. Although she could say the words “baba” or “mama” at the age of 2 years, she displayed a regression in development and only showed signs of unconscious articulation subsequently. Poor eye contact, head shaking, hand clapping, hand wringing, and bruxism were observed at the age of 1 year 3 months. Purposeful hand use was presented and retained. She experienced recurrent, febrile or non-febrile, generalized tonic-clonic seizures at the age of 11 months. Dystonic seizure occurred at 14 months. LEV was administered at the age of 16 months and the patient achieved seizure-free status at the age of 2.5 years. Her EEG (15 months and 2.5 years) and MRI (3 year) findings revealed normal findings ().