| | L-transposition and ccTGA |
| | Lachiewicz Sibley syndrome |
| | Lacrimo-auriculo-dento-digital syndrome |
| | Lactate dehydrogenase deficiency |
| | Lactate dehydrogenase deficiency type A |
| | Lactate dehydrogenase deficiency type B |
| | Lactate dehydrogenase deficiency type C |
| | Lactic acidosis congenital infantile |
| | Ladda Zonana Ramer syndrome |
| | Lagophthalmia cleft lip palate |
| | Lambdoid synostosis familial |
| | Lambert-Eaton Myasthenic Syndrome (Lambert-Eaton paraneoplastic cerebellar degeneration) |
| | Lamellar recessive ichthyosis |
| | Landouzy-Dejerine muscular dystrophy |
| | Langer Nishino Yamaguchi syndrome |
| | Langerhans cell granulomatosis |
| | Langerhans cell histiocytosis |
| | Laplane Fontaine Lagardere syndrome |
| | Large B cell diffuse lymphoma |
| | Larsen like osseous dysplasia dwarfism |
| | Larsen like syndrome lethal type |
| | Larsen syndrome craniosynostosis |
| | Larsen syndrome, dominant type |
| | Larsen syndrome, recessive type |
| | Laryngeal abductor paralysis mental retardation |
| | Laryngeal web congenital heart disease short stature |
| | Laryngomalacia dominant congenital |
| | Lassueur-Graham-Little syndrome |
| | Late onset dominant cone dystrophy |
| | Laterality defects dominant |
| | Lattice corneal dystrophy type 2 |
| | Launois-Bensaude adenolipomatosis |
| | Laurence Prosser Rocker syndrome |
| | Laurence-Moon-Bardet-Biedl syndrome |
| | Laxova Brown Hogan syndrome |
| | Leao Ribeiro Da Silva syndrome |
| | Lecithin cholesterol acyltransferase deficiency |
| | Left ventricle-aorta tunnel |
| | Leg absence deformity cataract |
| | Legg-Calve-Perthes syndrome |
| | Legionellosis, syn: Legionnaires' disease |
| | Leichtman Wood Rohn syndrome |
| | Leifer Lai Buyse syndrome |
| | Leigh syndrome, French Canadian type |
| | Leiomyomatosis of oesophagus cataract hematuria |
| | Leisti Hollister Rimoin syndrome |
| | Lentiginosis in context of NF |
| | Lenz Majewski hyperostotic dwarfism |
| | Lenz microphthalmia syndrome |
| | Leptomeningeal capillary - venous angiomatosis |
| | Lethal chondrodysplasia Moerman type |
| | Lethal chondrodysplasia Seller type |
| | Lethal congenital contracture syndrome |
| | Leukemia, B-Cell, chronic |
| | Leukemia, T-Cell, chronic |
| | Leukocyte adhesion deficiency syndrome |
| | Leukocyte adhesion deficiency type 2 |
| | Leukocytoclastic angiitis |
| | Leukodystrophy reunion type |
| | Leukodystrophy, Sudanophilic |
| | Leukodystrophy, globoid cell |
| | Leukodystrophy, metachromatic |
| | Leukodystrophy, psuedometachromatic |
| | Leukoencephalopathy palmoplantar keratoderma |
| | Leukomelanoderma mental retardation hypotrichosis |
| | Levic Stefanovic Nikolic syndrome |
| | Lewandowski Kikolich syndrome |
| | Lichen planus follicularis |
| | Lichen sclerosis et atrophicus |
| | Limb deficiencies distal micrognathia |
| | Limb scalp and skull defects |
| | Limb transversal defect cardiac anomaly |
| | Limb-girdle muscular dystrophy |
| | Linear hamartoma syndrome |
| | Lipidosis with triglycerid storage disease |
| | Lipoamide dehydrogenase deficiency |
| | Lipodystrophy Rieger anomaly diabetes |
| | Lipoid congenital adrenal hyperplasia |
| | Lipoid proteinosis of Urbach and Wiethe |
| | Lipomatosis central non-encapsulated |
| | Lipomatosis familial benign cervical |
| | Lipomucopolysaccharidosis |
| | Lisker Garcia Ramos syndrome |
| | Lison Kornbrut Feinstein syndrome |
| | Lissencephaly immunodeficiency |
| | Lissencephaly syndrome type 1 |
| | Lissencephaly syndrome type 2 |
| | Localized epiphyseal dysplasia |
| | Lockwood Feingold syndrome |
| | Loffredo Cennamo Cecio syndrome |
| | Loin pain hematuria syndrome |
| | Loose anagen hair syndrome |
| | Lopes Marques de Faria syndrome |
| | Low birth weight dwarfism dysgammaglobulinemia |
| | Lowe oculocerebrorenal syndrome |
| | Lower limb anomaly ureteral obstruction |
| | Lower limb deficiency hypospadias |
| | Lubani Al Saleh Teebi syndrome |
| | Lumbar malsegmentation short stature |
| | Lung agenesis heart defect thumb anomalies |
| | Lung herniation congenital defect of sternem |
| | Lupus anticoagulant, familial |
| | Luteinizing hormone releasing hormone, deficiency of with ataxia |
| | Lutz Richner Landolt syndrome |
| | Lutz-Lewandowsky epidermodysplasia verruciformis |
| | LyP (lymphomatoid papulosis) |
| | Lymphadenopathy, angioimmunoblastic with dysproteinemia |
| | Lymphangiectasies lymphoedema type Hennekam type |
| | Lymphangiomatosis, pulmonary |
| | Lymphedema hereditary type 1 |
| | Lymphedema hereditary type 2 |
| | Lymphedema-Distichiasis syndrome |
| | Lymphocytes reduced or absent |
| | Lymphocytic infiltrate of Jessner |
| | Lymphoma, gastric non Hodgkins type |
| | Lymphoma, large-cell, immunoblastic |
| | Lymphoma, small cleaved-cell, diffuse |
| | Lymphoma, small cleaved-cell, follicular |
| | Lymphomatoid granulomatosis |
| | Lymphomatoid papulosis (LyP) |
| | Lynch Lee Murday syndrome |
| | Lysine alpha-ketoglutarate reductase deficiency |
| | Lysinuric protein intolerance |
| | Lysosomal alpha-D-mannosidase deficiency |
| | Lysosomal beta-mannosidase deficiency |
| | Lysosomal glycogen storage disease with normal acid maltase activity |
| |