Allelic expression of IMPACT. (A) SNAS assay for allelic expression of IMPACT. The cDNAs from brain, liver, and adrenal gland from the informative 1155 C/T heterozygote fetus and two adult blood samples were subjected to the SNAS assay (labeled as RT+ in lanes 3, 5, 8, 10, 13,16, 19). The SNAS assay products from the genomic DNA are labeled as D (lanes 2, 7, 12,15, 18), whereas those from mock reverse-transcribed samples are shown as the negative control (labeled as RT− in lanes4, 6, 9, 11, 14,17, 20). A control of brain cDNA from a C/C subject is shown in lane 21 (designated as C). Lanes 1 and22 contain a 10-base ladder marker. The positions of the extended product and primer for each allele are indicated. (B) Allelic expression of IMPACT by PCR-RFLP. The cDNAs from the 3104 G/T heterozygous fetus (fetus no. 13466, lane 9) were amplified by primers 119 and 220, and then labeled by primer 219 (see Methods). Digestion with ApoI revealed the two parental alleles (G and T, 140 bp and 92 bp, respectively). Lanes 1–7are cDNAs from the indicated fetal tissues. Lane 8 is cDNA from the maternal endometrium. Genomic DNAs from the informative fetus (lane 9) and a G/G homozygote (lane 10) are shown as controls.