49,XXXXX syndrome http://purl.bioontology.org/ontology/MESH/C535319 http://purl.bioontology.org/ontology/SNOMEDCT/43248007 http://purl.obolibrary.org/obo/NCIT_C89802 49, XXXXX syndrome A rare sex chromosome abnormality in which a female child has 3 extra X chromosomes. XXXXX syndrome chromosome XXXXX syndrome penta X syndrome penta-X syndrome pentasomy X syndrome chromosomal gain syndrome 49,XXXXX allosomal chromosomal syndrome