LADD Syndrome is a rare genetic disorder characterized by abnormalities affecting the lacrimal and salivary glands and ducts, ears, teeth and fingers and toes.

Lafora Disease is a rare genetic disorder characterized by the presence of Lafora bodies, within neurons and the cells of the heart, liver, muscle, and skin.

Lambert-Eaton Myasthenic Syndrome is a rare autoimmune disorder which affects calcium delivery to the nerve-muscle junctions.

Lamellar Ichthyosis is a rare inherited skin disorder.

Landau-Kleffner Syndrome is a childhood disorder characterized by the loss of the ability to understand and use spoken language.

Langerhans cell histiocytosis (LCH) is a rare disorder in which abnormal, clonally proliferating (rapidly dividing identical cells originating from a single precursor) cells called Langerhans-ty...

A Large or Giant Congenital Melanocytic Nevus (plural: Nevi) is a pigmented lesion, substantial in size, either present at birth or very shortly after birth (within 2 years). These rare large birt...

Large granular lymphocyte leukemia (LGLL) is a rare form of leukemia affecting the white blood cells called “lymphocytes”. Leukemia is a term referring to cancer in the blood, causin...

Lateral Medullary Syndrome is a rare disorder characterized by difficulty swallowing or speaking due to dead tissue.

Lateral Meningocele Syndrome is a rare disorder characterized by multiple lateral meningoceles (meninges protrude from a spinal opening).

Leber Hereditary Optic Neuropathy (LHON) is a rare, maternally inherited mitochondrial disease that causes rapid, painless loss of central vision. It primarily affects the retinal ganglion cells...

Leber's Congenital Amaurosis is a rare inherited eye disorder.

Ledderhose’s disease, also called plantar fibromatosis, is a rare, benign disorder characterized by the abnormal growth within the connective tissue that supports the bottom of t...

Legg-Calve-Perthes Syndrome is a degenerative disease of the hip joint.

Leigh Syndrome is a rare genetic disorder caused by mutations in mitochondrial DNA or by deficiencies of an enzyme called pyruvate dehydrogenase.

Leiomyosarcoma is a rare form of cancer arising from muscle tissue.

Lemierre's Syndrome is a rare disorder characterized by oropharyngeal infection, usually caused by Fusobacterium necrophorum.

Lennox–Gastaut Syndrome is a rare form of childhood-onset epilepsy.

Léri-Weill Dyschondrosteosis is a rare disorder which results in dwarfism.

Lewis-Sumner Syndrome is a dysimmune multifocal demyelinating sensorimotor neuropathy.

Leydig cell tumors are rare tumors of the testis derived from the interstitial cells.

Lichen sclerosus (LS) is a chronic, inflammatory, skin and mucosal disease that most commonly affects the anogenital region (vulva, penis and perianal area), although it can appear in skin from ...

Liddle’s syndrome is a rare disease involving higher than normal kidney activity which leads to hypertension, or high blood pressure. A channel in the kidney epithelial layer, EN...

Light chain deposition disease (LCDD) is a rare disorder in which abnormal monoclonal immunoglobulin light chains, a protein component of antibody molecules, accumulate in tissues. The...

Linear Morphea is a variant of localized scleroderma usually occurring along the length of a limb or around the trunk.

Lipodermatosclerosis is a rare skin disorder characterized by smooth, brown, tight and painful skin just above the ankle resulting in chronic venous insufficiency.

Lipodystrophy is a disorder characterized by loss of body fat in particular areas of the body.

Loin Pain Hematuria Syndrome is the combination of flank pain and blood in the urine that is otherwise unexplained.

Long-chain 3-hydroxyacyl-coenzyme A dehydrogenase deficiency is a rare disorder that prevents the body from converting certain fats to energy.

Loose Anagen Hair Syndrome is a rare disorder in which hair falls out easily and is pulled out easily.

Lowe Syndrome is a rare genetic disorder characterized by hydrophthalmia, cataracts, intellectual disabilities, aminoaciduria, reduced renal ammonia production and vitamin D-resistant rickets.

Lujan-Fryns syndrome is a rare genetic disorder which causes mental retardation and physical characteristics similar to those found in Marfan syndrome.

Lyell Syndrome is characterized by an allergic reaction to a medication or illness leading to rashes, blisters, and subsequent ski...

Lymphangioleiomyomatosis is a rare idiopathic disorder.

Lymphangiomatosis is a rare condition where a lymphangioma is present in a widespread or multifocal manner.

Lymphocytic Colitis is a rare disorder characterized by diarrhea.

Lymphomatoid Papulosis is a rare skin disorder suggestive of malignant lymphoma.