(A) A scheme of the genomic structure of TPO.According to GenBank accession no. D32046.10 Exon 0 (dashed box) corresponds to exon 1 of Chang et al.14In this reference, the initiation codon is located in exon 2. TheTPO genome was divided and amplified by nested PCR. Each PCR segment spans as described below: segment 1, from nucleotide (nt) 1240 to nt 1600; segment 2, from nt 3100 to nt 3696; segment 3, from nt 3626 to nt 4066; segment 4, from nt 5959 to nt 6440; segment 5, from nt 6390 to nt 6778; segment 6 from nt 6682 to nt 7071; and segment 7, from nt 6954 to nt 7545. (B) Hetero-duplex formation by amplified segment 2 PCR products. Hetero-duplex bands are indicated by an arrow. Lane 1, PCR products from a healthy volunteer alone as a control; lane 2, mixture of PCR products from FT-2 and control; and lane 3, PCR products from FT-2 alone. (C) Hetero-duplex analysis of segment 2 of all family members, except for FT-1. All of the ET-affected members display the hetero-duplex bands (FT-2, 3, 4, and 6). However, none of the healthy family members showed hetero-duplex formation in segment 2 (FT-5, 7, and 8). (D) Identification of the mutation in the segment 2 ofTPO gene. The upper panel shows the DNA sequence of wild-type allele, and the lower panel shows the mutant allele.