| Diagnosis | Omim Number | Sample Count |
| GALACTOKINASE DEFICIENCY | 230200 | 3 |
| GALACTOSEMIA | 230400 | 45 |
| GALACTOSIALIDOSIS; GSL | 256540 | 10 |
| GAND SYNDROME; GAND | | 1 |
| GANGLIOSIDOSIS, GENERALIZED GM1, TYPE I | 230500 | 7 |
| GANGLIOSIDOSIS, GENERALIZED GM1, TYPE II, OR JUVENILE TYPE | 230600 | 1 |
| GAUCHER DISEASE, TYPE I | 230800 | 10 |
| GAUCHER DISEASE, TYPE II | 230900 | 9 |
| GAUCHER DISEASE, TYPE III | 231000 | 5 |
| GELEOPHYSIC DYSPLASIA 1; GPHYSD1 | 231050 | 1 |
| GIANT PLATELET SYNDROME | 231200 | 4 |
| GILLES DE LA TOURETTE SYNDROME; GTS | 137580 | 62 |
| GLAUCOMA, PRIMARY OPEN ANGLE; POAG | 137760 | 51 |
| GLOMUS TUMORS, MULTIPLE | 138000 | 1 |
| GLUCOCORTICOID RESISTANCE, GENERALIZED; GCCR | | 2 |
| GLUCOSE-6-PHOSPHATE DEHYDROGENASE; G6PD | 305900 | 20 |
| GLUT1 DEFICIENCY SYNDROME 1; GLUT1DS1 | | 18 |
| GLUTARICACIDEMIA I | 231670 | 10 |
| GLUTARICACIDURIA IIA | 231680 | 1 |
| GLYCOGEN STORAGE DISEASE I | 232200 | 12 |
| GLYCOGEN STORAGE DISEASE IB | 232220 | 1 |
| GLYCOGEN STORAGE DISEASE II | 232300 | 79 |
| GLYCOGEN STORAGE DISEASE III | 232400 | 9 |
| GLYCOGEN STORAGE DISEASE IV | 232500 | 4 |
| GLYCOGEN STORAGE DISEASE V | 232600 | 4 |
| GLYCOGEN STORAGE DISEASE VI | 232700 | 1 |
| GLYCOGEN STORAGE DISEASE VII | 232800 | 6 |
| GLYCOGEN STORAGE DISEASE VIII (IX, INCLUDED) | 306000 | 14 |
| GONADAL DYSGENESIS | | 1 |
| GOUT | 138900 | 1 |
| GREIG CEPHALOPOLYSYNDACTYLY SYNDROME; GCPS | 175700 | 2 |
| GROWTH CONTROL, Y-CHROMOSOME INFLUENCED; GCY | 475000 | 2 |
| GROWTH HORMONE INSENSITIVITY SYNDROME | 262500 | 1 |
| GYRATE ATROPHY OF CHOROID AND RETINA; GACR | 258870 | 10 |