Genes from DisGeNet not mapping in network analyser

I’m performing a network analysis using DisGeNet and I’m finding that some genes aren’t mapping to known diseases (ie G6PC2 with any diabetes) and when I input them on their own (TIMM44, CEBPA, and G6PC2, all related with diabetic outcomes) they are not mapping to the database at all. Have I input something wrong here?

I’m wondering if, in the case of large networks, there’s a way to trim down the outcomes to only include specific MeSH Diseases Classes (ie, omit respiratory tract diseases if I’m only interested in metabolic diseases).

Thank you!