| Syndrome |
Gene |
Chromosome |
Location |
Category |
OBESITY HYPERPHAGIA AND DEVELOPMENTAL DELAY | OBHD | 9 | q21.33 | Autism spectrum |
| | Ochoa syndrome | HPSE2 | 10 | q23-24 | Cerebral palsy | |
| Ocular albinism type 1 | GPR143 | 23 | p22.2 | Photophobia - sensitivity to light | |
| Oculocutaneous albinism - autosomal recessive | LRMDA | 10 | q22.2 | Photophobia - sensitivity to light | |
| Oculocutaneous albinism type 1 | MCR1 | 16 | q24.3 | Photophobia - sensitivity to light | |
| Oculocutaneous albinism type 1 | TYR | 11 | q14.3 | Photophobia - sensitivity to light | |
| Oculocutaneous albinism type 2 | OCA2 | 15 | q12 | Photophobia - sensitivity to light | |
| Oculocutaneous albinism type 3 | TYRP1 | 9 | p23 | Photophobia - sensitivity to light | |
| Oculocutaneous albinism type 4 | SLC45A2 | 5 | p13.2 | Photophobia - sensitivity to light | |
| Oculocutaneous albinism type 6 | SLC24A5 | 15 | q21.1 | Photophobia - sensitivity to light | |
| Oculodentodigital dysplasia | GJA1 | 6 | q22.31 | Microcephaly | |
| Oculofaciocardiodental (OFCD) syndrome | BCOR | 23 | p11.4 | Cataracts | |
| Oculopharyngeal muscular dystrophy | PABPN1 | 14 | q11.2 | Muscular dystrophies | |
| OGDEN SYNDROME | OGDNS | 23 | q28 | Autism spectrum | |
| OKUR-CHUNG NEURODEVELOPMENTAL SYNDROME | OCNDS | 20 | p13 | Autism spectrum | |
| Omenn syndrome | CARD11 | 7 | p22.2 | Alopecia | |
| Omenn syndrome | DCLRE1C | 10 | p13 | Alopecia | |
| Omenn syndrome | IL7R | 5 | p13.2 | Alopecia | |
| Omenn syndrome | LIG4 | 13 | q33.3 | Alopecia | |
| Omenn syndrome | RAG1 | 11 | p12 | Alopecia | |
| Omenn syndrome | RAG2 | 11 | p12 | Alopecia | |
| Ophthalmo-acromelic syndrome | SMOC1 | 14 | q24.2 | Cleft lip / cleft palate | |
| OPIOID RECEPTOR MU-1 | OPRM1 | 6 | q25.2 | Autism spectrum | |
| Opitz G/BBB syndrome | MID1 | 23 | p22 | Cleft lip / cleft palate | |
| Opitz G/BBB syndrome | SPECC1L | 22 | q11.23 | Cleft lip / cleft palate | |
| Optic atrophy type 01 | OPA1-one | 3 | q29 | Ataxia spectrum | |
| Optic atrophy with ataxia mental retardation and seizures type 10 | RTN4IP1 | 6 | q21 | Ataxia spectrum | |
| Oral-facial-digital syndrome | OFD1 | 23 | p22 | Cleft lip / cleft palate | |
| Ornithine translocase deficiency | SLC25A15 | 13 | q14.11 | Ataxia spectrum | |
| Orthostatic intolerance syndrome | SLC6A2 | 16 | q12.2 | Tachycardia (>100 beats/minute) | |
| Osteodysplastic primordial dwarfism type II | PCNT | 21 | q22.3 | Microcephaly | |
| OSTEOGENESIS IMPERFECTA TYPE XV | OI15 | 12 | q13.12 | Autism spectrum | |
| OTU DOMAIN-CONTAINING PROTEIN 7A | OTUD7A | 15 | q13.3 | Autism spectrum | |