HPLC chromatograms of the single nucleotide primer extension product to distinguish the 2 alleles in exon 14 to 15 RT-PCRs. The presence of 2 peaks in the DNA-PCR (C and G at codon 1241 and C and A at codon 1269, respectively) indicate that this is an informative marker in females. The analysis of the DNA-PCR product that showed 2 alleles (2 peaks) and the RT-PCR product that showed the presence of only 1 allele (1 peak) indicate a monoallelic expression.