Expression of normal and mutated STEAP3/TSAP6 alleles in lymphocytic cell lines from the father and the 3 affected children. Lymphocytic cell lines were cultured in the presence of emetin for 24 hours before being harvested, to prevent nonsense-mediated mRNA decay of the mutated mRNA. Electrophoregrams show that the ratio of the C (normal) to the A (mutated) allele is higher in the unaffected father than in his 3 affected offspring. Quantification of this expression ratio normalized for the C to A ratio in the mutated genomic DNA was performed using the “peak picker” software. Sequencing replicates from 3 independent RT-PCR were used to calculate the allelic ratios. The allelic ratios were 1.72 ± 0.05 in the father and 1.19 ± 0.03, 1.14 ± 0.027, 1.27 ± 0.032 in the affected children (mean ± SD). The difference between the father and each of his children was highly significant (P < .001, Student t test).