2.1. Subjects

The family in this study had 3 generations from which blood samples for DNA preparations were collected: grandmother (I-2), mother (II-2), and two children (III-2 and III-3). The II-2 was a single mother; therefore, we could not obtain blood for DNA from the father. The index case (III-2) had a third-degree AV block and had undergone cardiac surgery for epicardial pacemaker implantation at the age of 18 months. She was diagnosed with autism according to the DSM-IV at the age of 6 years. The other two siblings had no heart defects but one had learning disability (III-1, no DNA) and the other was autistic (III-3) (Figure 1). Extracted DNA samples from III-2 and III-3 were controlled for their quality by measuring DNA concentration using Nanodrop ND1000 and measuring fragmentation of DNA by agarose gel electrophoresis. These 2 samples were prepared for whole exome sequencing. DNA samples from other family members (I-2, II-2) were prepared for segregation analysis. Written informed consent was obtained from adult family members themselves and for all children and all procedures were approved by the Institutional Review Board (MURA2012/02/SN1) of the Faculty of Medicine Ramathibodi Hospital, Mahidol University, and EC48/364-006-3 of the Faculty of Medicine, Prince of Songkla University.

Electrocardiography of index case (III-2) shows third-degree atrioventricular block, atrial rate 100/min, ventricular rate 49/min, and ventricular pacing spikes before some QRS complexes.