Display genetic variations, bibliographic information according to a disease introduced (Federated query)

Endpoints: 
Query: 
select* where{ {SERVICE <$endpoint-1$> { ?s<http://www.w3.org/1999/02/22-rdf-syntax-ns#type><http://bio2rdf.org/pharmgkb_vocabulary:disease-haplotype-Association> . ?s<http://bio2rdf.org/pharmgkb_vocabulary:disease>?disease . ?disease<http://purl.org/dc/terms/title>?disease_name . ?s<http://bio2rdf.org/pharmgkb_vocabulary:article>?article . ?disease_name bif:contains "'??disease'" . } } OPTIONAL{ {SERVICE <$endpoint-2$> { ?article<http://purl.org/dc/terms/title><http://bio2rdf.org/pubmed_vocabulary:PubMedRecord> . ?Pubmed<http://purl.org/dc/terms/title>?article_title . } } } } limit ??number
Statement: 
Display genetic variations, bibliographic information accoding to a disease introduced $disease$ (e.g., neutropenia, stomach neoplasms, ovarian neoplasms or drug toxicity ).
A limit of results per page $number$ (e.g.100)