Dear Shawn,
The paper you cite is from 1992, in the pre-genomic era. Many proteins have the initial Methionine removed
after translation.
In the early days, many proteins were numbered without the Met. That may account for the off-by-one situation
you observe. As OMIM is reporting on the 1992 paper, it echoes the nomenclature from the paper. The rsID
There is an early variant the hemoglobin gene from that period that is famous for this situation. It is easy to see
at the 5'-end of the HBB gene, where the start codon is nearby.
In OMIM, you see
Hemoglobin Tyne
and if you read the entry, it refers to "codon 5." In the Browser, you see that it is the proline #6 if you count
the MET, and would be #5 in the literature of the time (1994). See it highlighted in the Browser:
best regards,
--b0b kuhn
Robert Kuhn, PhD
Associate Director UCSC Genome Browser (retired)
dba Robert Kuhn Consulting