Untersuchungen zu familiären und rassespezifischen ...

can also cause a deficiency of R-protein or IF. However, lack of IF is mostly due to
exocrine pancreatic insufficiency in dogs and not due to gastric disorders (Batt et al.,
1989). Selective cobalamin malabsorption caused by primary receptor defects is
also described. The human Imerslund-Gräsbeck-Syndrome can also occur in dogs
(Fyfe et al., 1991).
Little is known about the causes and pathogenesis of the lundehund-
gastroenteropathy yet. Therefore, a primary receptor defect cannot be excluded as
the cause for the cobalamin malabsorption in the lundehund.
Cobalamin malabsorption can be caused by defects in one of the elements in the
absorption pathway. One form of cobalamin malabsorption was described in the
Giant Schnauzer (Fyfe et al., 2004). CUBN could be excluded for this defect, but it
was mapped near the AMN-gene (Xu et al., 1999; He et al., 2003). A 33 bp (c.1113-
1145del) deletion was found in the AMN cDNA (NC_006590.1) of a kindred of
affected Giant Schnauzers. In a family of Australian Shepherds with subnormal
cobalamin serum levels a G>A transition (c.3G>A) was found in the AMN cDNA
(NC_006590.1) sequence. This mutation showed complete co-segregation with the
affection status of the dogs. So there are two mutations in the AMN gene coding for a
subunit of the cubam receptor that can cause cobalamin malabsorption in dogs (He
et al., 2005).
The aim of this study was to examine whether mutations of the AMN gene are
associated with the GE in Norwegian lundehunds.