| Diagnosis | Omim Number | Sample Count |
| OBESITY | 601665 | 58 |
| ORNITHINE TRANSCARBAMYLASE DEFICIENCY, HYPERAMMONEMIA DUE TO; OTC | 311250 | 96 |
| OROFACIAL CLEFT 1; OFC1 | 119530 | 17 |
| OSTEOCHONDRODYSPLASIA, RHIZOMELIC WITH CALLOSAL AGENESIS, THROMBOCYTOPENIA, HYDROCEPHALUS, AND HYPERTENSION | 166990 | 2 |
| OSTEOGENESIS IMPERFECTA, TYPE I; OI1 | 166200 | 11 |
| OSTEOGENESIS IMPERFECTA, TYPE II; OI2 | 166210 | 3 |
| OSTEOGENESIS IMPERFECTA, TYPE IV; OI4 | 166220 | 81 |
| OSTEOGENESIS IMPERFECTA: GENETICS UNCERTAIN; LETHAL | | 4 |
| OSTEOGENESIS IMPERFECTA: GENETICS UNCERTAIN; NON-LETHAL | | 7 |
| OSTEOGENIC SARCOMA | 259500 | 1 |
| OSTEOPETROSIS WITH RENAL TUBULAR ACIDOSIS | 259730 | 12 |
| OTHER DYSTONIA | | 6 |
| OTHER DYSTONIA SYNDROME | | 15 |
| OTOPALATODIGITAL SYNDROME, TYPE 1; OPD1 | 311300 | 1 |
| OXALOSIS TYPES I OR II, GLYCOLIC OR GLYCERIC ACIDURIA - 259900 OR 260000 | 259900 | 3 |
| OXALOSIS TYPES I OR II, GLYCOLIC OR GLYCERIC ACIDURIA - 259900 OR 260000 | 260000 | 3 |