PON1 was detected only from the paternal allele in human-mouse monochromosomal hybrids. Since PON1
expression was undetectable in human lymphoblasts direct evidence of imprinting was not obtained (Okita
C et al, 2003).
Since no additional data have been published on PON1 imprinting (2008) and since it is a widely
studied gene, it is no longer included in the list of provisionally imprinted genes.