chromosomal disease Down syndrome Downs syndrome disease_ontology MTHICD9_2006:758.0 Down's syndrome - trisomy 21 MESH:D004314 NCI:C2993 DOID:14250 OMIM:190685 ICD10CM:Q90.9 trisomy 21 syndrome G Trisomy NCI2004_11_17:C2993 Complete trisomy 21 syndrome GARD:10247 UMLS_CUI:C0013080 A chromosomal disease that is characterized by flat-looking facial features and weak muscle tone (hypotonia) in infancy and is caused by trisomy of all or a critical portion of chromosome 21 and is associated with intellectual disability. CSP2005:1254-8068 OMIM mapping confirmed by DO. [SN]. Down's syndrome ICD10CM:Q90 ICD9CM:758.0 SNOMEDCT_US_2018_03_01:41040004