The L-gulono-gamma-lactone oxidase gene (GULO) which is a candidate for vitamin C deficiency in pigs maps to chromosome 14

Vitamin C deficient pigs, when fed a diet lacking L-ascorbic acid (AscA), m anifest deformity of the legs, multiple fractures, osteoporosis, growth ret ardation and haemorrhagic tendencies. This trait was shown by others to be controlled by a single autosomal recessive allele designated as od (osteoge nic disorder). The inability of AscA biosynthesis in primates and guinea pi gs that exhibit similar symptoms, when they are not supplemented with AscA in the food, was traced to the lack of L-gulono-gamma-lactone oxidase, whic h catalyzes the terminal step in the biosynthesis of AscA, The non-function al GULOP was mapped to human chromosome 8p21 that corresponds to an evoluti onarily conserved segment on either porcine chromosome 4 (SSC4) or 14 (SSC1 4). We investigated linkage between OB and SSC4- and 14-specific microsatel lite loci in order to map the OD locus. Twenty-seven informative meioses in families from one sire and three dams revealed linkage of od with microsat ellites SW857 and S0089, located in the subcentromeric region of SSC14. We isolated part of the GULO gene of the pig by screening a porcine genomic li brary using a pig GULO cDNA as a probe, and mapped it to SSC14q14 by fluore scence in situ hybridization (FISH), Thus, the porcine GULO gene is both a good physiological and positional candidate gene for vitamin C deficiency i n pigs.