Comparison of exon 12–skipping in various tissues from wild-type, patient, and patient's sister (heterozygote). (A) Genomic DNA was isolated from reticulocytes and the exon/intron boundary of exon 12/intron 12, and was amplified by PCR. PCR products were subjected to digestion with BsiW I endonuclease and then analyzed on a 1% agarose gel. (B) RNA was isolated from mononuclear cells, granulocytes, platelets, and reticulocytes, and total cDNA was synthesized. The exon 9 to 13 region of DMT1 cDNA was amplified by PCR and the PCR products were separated on a 1% agarose gel. Lanes 1, 5, and 9 are from mononuclear cells; lanes 2, 6, and 10 are from granulocytes; lanes 3, 7, and 11 are from platelets; lanes 4, 8, and 12 are from reticulocytes.