45,X/46,XY mixed gonadal dysgenesis (MONDO_0015779, a Monarch Disease Ontology id) (45,X/46,XY MGD) is a disorder of sex development (DSD) associated with a numerical sex chromosome abnormality resulting from Y-chromosome mosaicism and leading to abnormal gonadal development. Also known as: 45,X/46,XY MGD, 45,X/46,XY disorder of Sex development, 45,X/46,XY gonadal dysgenesis, 45,X0/46,XY MGD, 45,X0/46,XY mixed gonadal dysgenesis, Mixed gonadal dysgenesis, XY/X0.