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: Autosomal dominant myotonia congenita is an inherited disorder of skeletal muscle caused by mutations in a voltage - gated Cl - channel gene ( CLCN1 , 7q35 ) .
### Output Text:
<span class="disease">Autosomal dominant myotonia congenita</span> is an <span class="disease">inherited disorder of skeletal muscle</span> caused by mutations in a voltage - gated Cl - channel gene ( CLCN1 , 7q35 ) . 