KCNJ2 and Andersen-Tawil syndrome: In the family affected by ATS, molecular genetic screening revealed the heterozygous point mutation c.434A > G in exon 2 of the KCNJ2 gene leading to an amino acid substitution of tyrosine to cysteine at position 145 (p.Y145C) in the expressed ion channel protein Kir2.1.