| Diagnosis | Omim Number | Sample Count |
| TAY-SACHS DISEASE, AB VARIANT | 272750 | 2 |
| TAY-SACHS DISEASE; TSD | 272800 | 31 |
| TELANGIECTASIA, HEREDITARY HEMORRHAGIC, OF RENDU, OSLER, AND WEBER; HHT | 187300 | 25 |
| TETRALOGY OF FALLOT | 187500 | 8 |
| TETRASOMY 18P | | 1 |
| THANATOPHORIC DYSPLASIA WITH KLEEBLATTSCHAEDEL | 187601 | 3 |
| THANATOPHORIC DYSPLASIA; TD | 187600 | 15 |
| THANATOPHORIC DYSPLASIA; UNKNOWN TYPE | | 2 |
| THROMBOCYTOPENIA | 188000 | 1 |
| TOURETTE SYNDROME | 137580 | 3047 |
| TRANSIENT ISCHEMIC ATTACK | 601367 | 183 |
| TRICARBOXYLIC ACID CYCLE, DEFECT OF | 275370 | 1 |
| TRICHORHINOPHALANGEAL SYNDROME, TYPE I; TRPS1 | 190350 | 1 |
| TRICHORHINOPHALANGEAL SYNDROME, TYPE II; TRPS2 (LANGER-GIEDION SYNDROME; LGS) | 150230 | 1 |
| TRICHOTHIODYSTROPHY 3, PHOTOSENSITIVE; TTD3 | | 5 |
| TRICHOTHIODYSTROPHY, NONPHOTOSENSITIVE 1; TTDN1 | 234050 | 3 |
| TRICHOTHIODYSTROPHY; TTD ICHTHYOSIFORM ERYTHRODERMA WITH HAIR ABNORMALITY AND MENTAL AND GROWTH RETARDATION, INCLUDED | 601675 | 15 |
| TRIFUNCTIONAL PROTEIN DEFICIENCY | 609015 | 2 |
| TRIOSEPHOSPHATE ISOMERASE DEFICIENCY; TPID | | 1 |
| TRISOMY 21 | 190685 | 62 |
| TUBEROUS SCLEROSIS 1; TSC1 | 191100 | 30 |
| TUBEROUS SCLEROSIS 2; TSC2 | | 60 |
| TUMORAL CALCINOSIS, HYPERPHOSPHATEMIC, FAMILIAL; HFTC | 211900 | 3 |
| TURCOT SYNDROME | 276300 | 2 |
| TURNER SYNDROME | | 29 |
| TYROSINE TRANSAMINASE DEFICIENCY | 276600 | 1 |
| TYROSINEMIA, TYPE I | 276700 | 1 |