| | N acetyltransferase deficiency |
| | N-acetyl glutamate synthetase deficiency |
| | N-acetyl-alpha-D-galactosaminidase |
| | N-acetyl-glucosamine-6-sulfate sulfatase deficiency |
| | NADH CoQ reductase, deficiency of |
| | NADH cytochrome B5 reductase deficiency |
| | Nakajo Nishimura syndrome |
| | Nanism due to growth hormone combined deficiency |
| | Nanism due to growth hormone isolated deficiency with X linked hypogammaglobulinemia |
| | Nanism due to growth hormone resistance |
| | Narrow oral fissure short stature cone shaped epiphyses |
| | Nasodigitoacoustic syndrome |
| | Nasopalpebral lipoma coloboma syndrome |
| | Nasopharyngeal teratoma Dandy Walker diaphragmatic hernia |
| | Natal teeth intestinal pseudoobstruction patent ductus |
| | Necrotizing encephalopathy, infantile subacute |
| | Negative rheumatoid factor polyarthritis |
| | Nemaline Myopathy, Amish Type |
| | Neonatal transient jaundice |
| | Nephroblastomatosis, fetal ascites, macrosomia and Wilm's tumor |
| | Nephrogenic diabetes insipidus |
| | Nephronophthisis familial adult spastic quadriparesis |
| | Nephropathy deafness hyperparathyroidism |
| | Nephropathy familial with hyperuricemia |
| | Nephropathy, familial with gout |
| | Nephrosis deafness urinary tract digital malformation |
| | Nephrosis neuronal dysmigration syndrome |
| | Nephrotic syndrome ocular anomalies |
| | Nephrotic syndrome, idiopathic, steroid-resistant |
| | Nesidioblastosis of pancreas |
| | Netherton syndrome ichthyosis |
| | Neuhauser Daly Magnelli syndrome |
| | Neuhauser Eichner Opitz syndrome |
| | Neural tube defect, folate-sensitive |
| | Neural tube defects X linked |
| | Neuraminidase beta-galactosidase deficiency |
| | Neuritis with brachial predilection |
| | Neuroaxonal dystrophy renal tubular acidosis |
| | Neuroaxonal dystrophy, late infantile |
| | Neuroectodermal endocrine syndrome |
| | Neuroectodermal tumors primitive |
| | Neuroendocrine carcinoma of the cervix |
| | Neurofaciodigitorenal syndrome |
| | Neurofibromatosis, Type IV, of Riccardi |
| | Neurofibromatosis, familial intestinal |
| | Neurofibromatosis-Noonan syndrome |
| | Neuroleptic malignant syndrome |
| | Neuronal interstitial dysplasia |
| | Neuronal intestinal pseudoobstruction |
| | Neuronal intranuclear hyaline inclusion disease |
| | Neuronal intranuclear inclusion disease |
| | Neuropathy ataxia and retinis pigmentosa |
| | Neuropathy congenital sensory neurotrophic keratitis |
| | Neuropathy hereditary with liability to pressure palsies |
| | Neuropathy motor sensory type 2 deafness mental retardation |
| | Neuropathy sensory spastic paraplegia |
| | Neuropathy, hereditary motor and sensory, LOM type |
| | Neuropathy, hereditary sensory, type I |
| | Neuropathy, hereditary sensory, type II |
| | Neutral lipid storage myopathy |
| | Neutropenia monocytopenia deafness |
| | Neutropenia, severe chronic |
| | Nevi flammei, familial multiple |
| | Nevoid basal cell carcinoma syndrome |
| | Nevus of ota retinitis pigmentosa |
| | Nevus sebaceus of Jadassohn |
| | Nicolaides Baraitser syndrome |
| | Niemann-Pick disease type C |
| | Niemann-Pick disease type D |
| | Night blindness skeletal anomalies unusual facies |
| | Night blindness, congenital stationary |
| | Nijmegen Breakage Syndrome |
| | Nivelon Nivelon Mabille syndrome |
| | Noble Bass Sherman syndrome |
| | Non functioning pancreatic endocrine tumor |
| | Non-lissencephalic cortical dysplasia |
| | Non-small cell lung cancer |
| | Nonallergic atopic dermatitis |
| | Noninsulin-dependent diabetes mellitus with deafness |
| | Nonketotic hyperglycinemia |
| | Nonmedullary thyroid carcinoma, with cell oxyphilia |
| | Nonsyndromic hereditary hearing impairment |
| | Norman Roberts lissencephaly syndrome |
| | Normokalemic periodic paralysis |
| |