There are two gene sequences for human apolipoprotein CI (apo CI) on chromosome 19, one of which is 4 kb from the gene for apo E.

@article{Davison1986ThereAT,
  title={There are two gene sequences for human apolipoprotein CI (apo CI) on chromosome 19, one of which is 4 kb from the gene for apo E.},
  author={Patrick J Davison and Paul Norton and Steven C. Wallis and Leicester Gill and Martyn Cook and R. Williamson and Steve E Humphries},
  journal={Biochemical and biophysical research communications},
  year={1986},
  volume={136 3},
  pages={876-84}
}
A cDNA probe corresponding to the mRNA sequence for apolipoprotein E (apo E) was used to screen two independently-constructed human genomic libraries. Two recombinants (lambda E-2, and lambda E2-1), isolated using the apo E cDNA probe, also contain part or all of the apo CI gene. Hybridisation studies using both apo E and apo CI cDNA probes show that these two genes are in the same orientation and separated by 4 kb.