Details behind the European Patent Office’s (EPO) decision in May 2004 to revoke Myriad Genetic’s 2001 BRCA1 gene patent have been made public. The main claim related to a method of diagnosing a predisposition to human breast/ovarian cancer by analysing mutations in the BRCA1 gene. The gene was defined broadly by reference to a specific amino-acid sequence and variant sequences "with at least 95% identity to that sequence". The Opposition Division of the EPO rejected the claims of the granted patent on the grounds that there was inadequate basis in the application as originally filed for inserting the feature "with at least 95% identity" into claim 1 of the granted patent. Several sets of amended claims filed by Myriad were then considered in turn by the EPO.

Myriad first tried to avoid the limitation of the claims to a specific BRCA1 sequence by removing the sequence from the claims, arguing that the term ‘BRCA1 gene’ was clear in itself and that the sequence of the gene was not necessary to carry out the invention. This was rejected by the EPO on the grounds that the sequence was an essential technical feature of the claim and also that its removal would illegally extend the scope of the patent. Myriad then tried to amend the claims to refer to the specific BRCA1 gene sequence and also to several specific mutations that are characteristic of breast and ovarian cancers.

The priority date of the claims then became a key issue, because a sequence of the BRCA1 gene and details of all three mutations claimed by Myriad were published in the interval between the filing of Myriad’s earliest US priority application and their European patent application.   Myriad’s original patent filing in 1994 contained several errors in the DNA sequence of the BRCA1 gene. In 1995, the company had submitted a revised sequence, correcting the errors but it turned out that the new sequences had already been published.  Myriad has until 21 January 2005 to file an appeal.

This shows the strict approach that the EPO takes regarding claim amendments and priority for gene sequences.   It’s just an example of the need to be incredibly stringent in filing gene applicaitons.

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