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. 2015 Mar 16;125(4):1703–1707. doi: 10.1172/JCI64415

Figure 2. LOH mapping of the IWC-II locus and identification of a de novo mutation in KRT1.

Figure 2

(A) Genotyping of LCM revertant tissue DNA shows heterozygous genotypes from 12pter to 48-Mb base pairs, while from 48-Mb base pairs to 12qter, genotypes are homozygous, indicating LOH. Genotype intensity remains stable over this interval of LOH (logR ratio), and copy number remains at 2, supporting a copy-neutral mechanism. LOH intervals from 5 revertant spots are shown, with breakpoints occurring between 44.3- and 49.1-Mb base pairs. KRT1 lies at 53.1-Mb base pairs. (B) A de novo single-base (G) insertion in KRT1 exon 9 is present in the index case but neither parent; this mutation is transmitted to affected offspring (data not shown). TA cloned sequence is shown for clarity. (C) This mutation results in a C-terminal frameshift replacing the last 22 amino acids of the C-terminus of KRT1 with a novel 30–amino acid peptide (p.622V>CfsX30) (shown in red below the corresponding normal KRT1 tail).