Genetic analysis of a Japanese family with normotriglyceridemic abetalipoproteinemia indicates a lack of linkage to the apolipoprotein B gene.

Normotriglyceridemic abetalipoproteinemia is a rare familial disorder characterized by an isolated deficiency of apoB-100. We have previously reported a patient with this disease, who had normal apoB-48 but no apoB-100. To elucidate the genetic abnormalities in this family, we studied the linkage of apoB gene using three genetic markers.
The proband and her affected brother showed completely different apoB gene alleles, suggesting that the apoB gene itself is not related to this disorder in this family.
By contrast, an American case had a point substitution in the apoB gene generating an in-frame stop codon.
These results indicate that this disorder can be caused by defect (s) of either an apoB gene or other genes.. 
