Molecular analysis of the human orosomucoid gene ORM1*Q0(koln) responsiblefor incompatibility in a German paternity case

In a German paternity test, an alleged father was excluded only by reverse homozygosity of ORM1 phenotypes (mother ORM1 S, child ORM1 S and alleged fa ther ORM1 Fl) out of the 28 classical and DNA markers investigated. Without the ORM1 system the biostatistical probability of paternity was calculated to exceed 99.9999%. The intensity of the immunoprinted bands of the ORM1 p rotein for the child and alleged father after isoelectric focusing appeared to be reduced to about half. To identify a possible null allele, gene-spec ific amplification followed by single-strand conformation polymorphism and sequencing analyses were carried out. Deletion of one of the two copies of a 4 bp direct repeat sequence (GTCT) in exon 4 of the consensus sequence of ORM1*F1 was observed in the child and alleged father. Thus, the sharing of a rare mutant gene, ORM1*Q0(koln), increased the probability of paternity.