Figure 2

Identification of a novel mutation, L187P, in KCNQ1 in LQTS family QW1648. (A). A partial pedigree structure for the large Utah family is shown. The family had over 300 members. For ease of illustration only a portion of the pedigree is shown. Affected males and females are indicated by filled squares and circles, respectively. Normal individuals are shown as empty symbols. Individuals with uncertain LQTS diagnosis are shown with gray symbols. Deceased individuals are shown using slashes. The identification numbers for family members and QTc are shown below symbols. (B). DNA sequence analysis revealed a heterozygous T→C transition at nucleotide 560 of KCNQ1, which results in a substitution of amino acid residue leucine by a proline residue (L187P). The sequence for a normal family member is shown on the top and the sequence for an affected family member is shown below. (C). SSCP analysis showed co-segregation of the mutation L187P with the LQTS phenotype in the family. All phenotypically affected members had two bands, and the non-affected individuals had only one band.