Long-term follow-up of a patient with type 2 Timothy syndrome and the partial efficacy of mexiletine.

We report a detailed case of type 2 TS due to a p.(Gly402Ser) mutation in exon 8 of the CACNA1C gene. The patient shows a marked prolongation of repolarization with a mean QTc of 540 ms. He shows no structural heart disease, syndactyly, or cranio-facial abnormalities. However, he shows developmental delays, without autism, and dental abnormalities. The cardiac phenotype is very severe, with a resuscitated cardiac arrest at 2.5 years of age, followed by 26 appropriate shocks during nine years of follow-up. Adding mexiletine to nadolol resulted in a reduction of the QTc and a slight decrease in the number of appropriate shocks.