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.
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 ().