Here are some sample queries, separated by lines of = signs.
The queries are in SPARQL.

=====================
SELECT
  ?syndrome ?name
WHERE
{
   syi:Alopecia syo:featureOf ?syndrome.
   ?syndrome syo:name ?name.
}

=====================
SELECT
    ?o ?name
WHERE
{
    syi:Hypotonia syo:featureOf ?o.  
    syi:SparseHair syo:featureOf ?o.
       ?o syo:name ?name.
}

====================

SELECT distinct
  ?if_patient_has ?it_might_be
WHERE
{
    # input
  syi:Hypotonia syo:featureOf ?syndrome.
  syi:MentalRetardation syo:featureOf ?syndrome.

    # part that doesn't change

  ?syndrome syo:name ?it_might_be.
    ?if_patient_has syo:featureOf    ?syndrome.
}
ORDER BY ?if_patient_has

=====================

SELECT distinct
  ?category ?if_patient_has ?it_might_be
WHERE
{
    # input
  ?s syo:featureOf ?syndrome.
     FILTER (regex(str(?s), "(?i)retard"))
  ?t syo:featureOf ?syndrome.
     FILTER (regex(str(?t), "(?i)hypotonia"))
  ?u syo:featureOf ?syndrome.
     FILTER (regex(str(?u), "(?i)clino"))

    # part that doesn't change

  ?syndrome syo:name ?it_might_be.
    ?if_patient_has syo:featureOf    ?syndrome.
  ?if_patient_has syo:inCategory ?category

}
ORDER BY ?category
====================

SELECT distinct
  ?category ?if_patient_has ?it_might_be
WHERE
{
    # input
  syi:Hypospadias syo:featureOf ?syndrome.
  ?s syo:featureOf ?syndrome.
     FILTER (regex(str(?s), "(?i)enceph"))

    # part that doesn't change

  ?syndrome syo:name ?it_might_be.
    ?if_patient_has syo:featureOf    ?syndrome.
  ?if_patient_has syo:inCategory ?category

}
ORDER BY ?category

=================
SELECT distinct
  ?category ?if_patient_has ?it_might_be
WHERE
{
    # input
  syi:Hypotonia syo:featureOf ?syndrome.
  ?s syo:featureOf ?syndrome.
     FILTER (regex(str(?s), "(?i)clinod"))

    # part that doesn't change

  ?syndrome syo:name ?it_might_be.
    ?if_patient_has syo:featureOf    ?syndrome.
  ?if_patient_has syo:inCategory ?category

}
ORDER BY ?it_might_be