underdiagnosis

noun

un·​der·​di·​ag·​no·​sis -ˌdī-ig-ˈnō-səs, -əg- 

plural underdiagnoses -ˌsēz 

: failure to recognize or correctly diagnose a disease or condition especially in a significant proportion of patients

… a growing body of research that demonstrates an underdiagnosis of heart disease in women, as well as a lack of understanding about gender variations in symptoms of heart disease …

—Florida Today (Brevard County, Florida)