The purpose of this study was to compare genomic sequences of oocysts derived from sporadic human cryptosporidiosis cases in Canada to the published genomic sequence of Cryptosporidium hominis at select gene loci distributed over several chromosomes. A total of 46 loci on 7 chromosomes were analyzed. Sequence polymorphisms were found at 50 positions on 22 loci in 20 different contigs. While some of these polymorphisms included synonymous single nucleotide polymorphisms (SNPs), many were non-synonymous (NS) and the largest variations included a locus with a 120bp deletion on chromosome (Chr) 7 and a locus with a 90bp insertion on Chr 3. Of the sequence variations found, 39 resulted in amino acid substitutions in the predicted protein sequences with the large insertion coding for a glutamine(Q)-rich pentameric repeat region. The results from this study showed that approximately half the loci sequenced were variant from the reported genomic sequence of the TU502 isolate from Uganda.
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