A missense mutation (R183H) followed by a single base-pair deletion resulting in a frameshift after I187. This frameshift likely results in nonsense-mediated decay, but if a stable protein product is produced from this allele it would include 147 random amino acids following the frameshift before a stop codon. Thus, only the N-terminal 187 amino acids of the 458 amino acid Orc4 protein would be wild type, and the resulting protein would likely be nonfunctional.