Discussion and Conclusions
We have presented evidence for a BP susceptibility locus near the centromere of chromosome 18. This susceptibility locus has been confirmed independently by Stine et al. (Am. J. Hum. Genet., 1995;57:1384). The evidence for linkage derives from kindreds in which fathers transmit illness to children. This susceptibility locus is valid only for a minority of BP kindreds, as only ~30% of BP kindreds are classified as paternal. This parent-of-origin effect is consistent with imprinting.
We have confirmed a second BP susceptibility locus on chr 21q22.3 (Straub et al., Nat. Genet. 1994;8:291). This locus seems to be more common among kindreds with maternal transmission of illness.