In the sentence extracted from biomedical literature, identify all the disease entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="disease"> to denote a disease.

### Input Text: This expanded population - based study confirms that the BRCA1 185delAG mutation and the BRCA2 6174delT mutation constitute the two most frequent mutation alleles predisposing to hereditary breast cancer among the Ashkenazim , and suggests a relatively lower penetrance for the 6174delT mutation in BRCA2
### Output Text:
This expanded population - based study confirms that the BRCA1 185delAG mutation and the BRCA2 6174delT mutation constitute the two most frequent mutation alleles predisposing to <span class="disease">hereditary breast cancer</span> among the Ashkenazim , and suggests a relatively lower penetrance for the 6174delT mutation in BRCA2 