Mismatch of genomic and transcript positions

[lacek]

I am trying to use transcript positions provided by UTA to convert cDNA positions to genomic positions.
I got a wrong result when working on the transcript NM_006331.7 where genomic and transcript positions are inconsistent.

By executing the query:

SELECT ord, tx_start_i, tx_end_i, alt_start_i, alt_end_i
FROM tx_exon_aln_v
WHERE tx_ac = 'NM_006331.7'
AND alt_aln_method = 'splign'
AND alt_ac = 'NC_000012.11'
ORDER BY ord;

The following results are returned:

ord	tx_start_i	tx_end_i	alt_start_i	alt_end_i
0	0	311	7079943	7080253
1	311	413	7083500	7083602
2	413	555	7083713	7083855
3	555	614	7084251	7084310
4	614	764	7084390	7084540
5	764	1072	7084857	7085165

In the first exon, tx_end_i - tx_start_i = 311bp but alt_end_i - alt_start_i = 310bp. I wonder if there is something wrong with the data. Or am I just querying improperly?