“No crime is so great as daring to excel.” — Winston Churchill

A little detective work traced the problem to default date format
conversions and floating-point format conversions in the very useful
Excel program package. The date conversions affect at least 30 gene
names; the floating-point conversions affect at least 2,000 if Riken
identifiers are included. These conversions are irreversible; the original gene names cannot be recovered.

Yet another reason not to use Excel as your “database”.