Figure 2. Electropherograms of the mutations detected in Protocadherin-21 (PCDH21). Panel A illustrates the index c.338delG mutation in family 1; the wild-type (WT) sequence is displayed on the top row. The middle row shows the proband in family 1 (IV-2) with a homozygous (HM) c.338delG change, illustrated with a dash for the missing nucleotide when aligned with the wildtype sequence. The bottom row displays an unaffected parent of family 1 (III-3) with the c.338delG change in the heterozygous state (Het): the latter section of the heterozygous electropherogram shows two superimposed sequences due to the synchronous addition of nucleotides due to two distinct DNA templates derived from the wild type and the shorter mutant alleles of the heterozygote. Panel B illustrates the second mutation that was identified in PCDH21, in family 2. The top row displays the control individual with the wildtype (WT) allele; while the bottom row displays the affected proband (II-1) with a homozygous (HM) c.1463delG variant.