I couldn't get the pipe to return the nucleotide sequence when using the gene database, although this would correctly identify the gene. I've corrected the command using the GI number as you suggested and this returns the correct result, thanks for the help!
Is there a way to use the gene database to return the fasta sequence? I have tried:
$ esearch -db gene query "LOC100136426" | efetch -format fasta
This didn't return the fasta sequence