query: sparql?query=#mtDNA Haplogroups
  SELECT ?item ?itemLabel ?p156 ?p156Label
  WHERE 
  {
    ?item wdt:P31 wd:Q1356230.
    OPTIONAL { ?item wdt:P156 ?p156 } #followed by
    
    SERVICE wikibase:label { bd:serviceParam wikibase:language "en". }
  }&format=json