[Genome] question about UCSC 'Human ESTs Including Unspliced' track

[xu_jianzhen]

Dear Genome Help,
  I've a question about UCSC 'Human ESTs Including Unspliced' track.The methods of this track said,"To generate this track, human ESTs from GenBank were aligned against the genome using blat. Note that the maximum intron length allowed by blat is 750,000 bases, which may eliminate some ESTs with very long introns that might otherwise align".However,to my knowledge of biology,i do not think there are too much such long pre-mRNA that is more than 750kb, so my question is when I find a unspliced EST more than 200kb,does it mean this is a false positive?
 
 
Thank you all!
 
 
 
Xu Jerry
GIBH,CAS