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All Communities

  • Macrophagic Myofasciitis

    1 members

    Macrophagic Myofasciitis, is a rare muscle disorder characterized by microscopic lesions found in muscle biopsies.

  • Macular Pucker

    1 members

    Macular Pucker is scar tissue that has formed on the eye's macula/retina.

  • Mal de Debarquement Syndrome

    5 members

    Mal de Debarquement Syndrome is a rare condition usually occurring after a cruise, aircraft flight, or other sustained motion event resulting in a persistent sensation of motion such as rocking, sw...

  • Malignant Hyperthermia

    2 members

    Malignant Hyperthermia is a rare disorder caused by exposure to certain drugs used for general anesthesia.

  • Malignant Nerve Sheath Tumors

    1 members

    Malignant peripheral nerve sheath tumor (MPNST) is a rare cancer type that affects the protective tissue that surrounds the nerves that come out the spinal...

  • Malignant Osteopetrosis

    3 members

    In osteopetrosis, osteoclasts do not function normally. Bone is deposited by osteoblasts, but not remodeled by osteoclasts. The results are dense hard bones that are actually more brittle because t...

  • Malonyl-Coenzyme A Decarboxylase Deficiency

    1 members

    Malonyl-Coenzyme A Decarboxylase Deficiency is a condition that prevents the body from converting some typs of fat to energy.

  • Mantle Cell Lymphoma

    2 members

    Mantle Cell Lymphoma is one of the rarer forms of non-Hodgkin's lymphoma.

  • Maple Syrup Urine Disease


    Maple Syrup Urine Disease is a rare disorder resulting in the buildup of the branched-chain amino acids in the blood and urine.

  • Marden-Walker Syndrome

    8 members

    Marden-Walker Syndrome is a rare disorder characterized by a distinct facial expression, a small or receding jaw, a cleft or high-arched palate, growth delay, bone joints in a fixed position and li...

  • Marfan Syndrome

    6 members

    Marfan Syndrome is a genetic disorder affecting roughly 200,000 Americans caused by mutations in the FBN1 gene.

  • Maroteaux-Lamy Syndrome

    1 members

  • MASA Syndrome

    1 members

    MASA syndrome is a rare neurological disorder characterized by Mental retardation, Aphasia, Shuffling gait, and Adducted thumbs.


  • Mayer-Rokitansky-Küster-Hauser Syndrome

    11 members


    Mayer-Rokitansky-Kuester-Hauser (MRKH) syndrome is a rare condition characterized by the failure of the uterus and the vagina to dev...

  • McKusick-Kaufman Syndrome

    2 members

    McKusick-Kaufman Syndrome is a rare developmental disorder characterized by extra fingers and/or toes, heart defects, and genital abnormalities.

  • Meckel Syndrome

    2 members

    Meckel Syndrome is a rare genetic disorder.

  • MECP2 Duplication Syndrome

    2 members

    MECP2 Duplication Syndrome is a rare brain disorder that causes severe intellectual disability, weak muscle tone, and seizures. It is caused by a duplication of the MECP2 gene.

  • Median Arcuate Ligament Syndrome

    2 members

    The diaphragm is a structure made of muscle and fibrous tissue that separates the chest cavity from the abdominal cavity and aids with breathing. There are a few openings or hiatus in ...

  • Medium-Chain Acyl-CoA Dehydrogenase Deficiency

    2 members

  • Medullary Cystic Kidney Disease

    6 members

    Medullary Cystic Kidney Disease is a rare kidney disorder.

  • Medullary Sponge Kidney

    4 members

    Medullary Sponge Kidney (MSK) is a rare disorder of the kidneys characterized by a cystic dilatation of the collecting tubules in the kidneys. MSK is a congenital disorder developed from bi...

  • Medullary thyroid carcinoma


    Medullary thyroid carcinoma is a rare form of thyroid carcinoma that originates in the parafollicular C cells of the thyroid gland.

  • Megalencephaly Cutis Marmorata Telangiectatica Congenita

    6 members

    Megalencephaly Cutis Marmorata Telangiectatica Congenita is a rare disorder characterized by an enlarged brain.

  • Megaloblastic Anemia


  • Melanoma

    4 members

    Melanoma is a malignant tumor of melanocytes which are found predominantly in skin but also in the bowel and the eye

  • MELAS Syndrome

    2 members

  • Melkersson–Rosenthal Syndrome


    Melkersson–Rosenthal Syndrome is a rare neurological disorder characterized by reoccurring facial paralysis, swelling of the face and lips, and the development of folds and furrows in the tongue.

  • Melnick-Needles Syndrome


    Melnick-Needles Syndrome is a rare genetic disorder of the bones, but also affects the soft body tissue such as the kidneys and the renal tract.

  • Membranoproliferative Glomerulonephritis

    4 members

    Membranoproliferative Glomerulonephritis is a rare progressive glomerulonephritis (type of kidney disease).

  • Mendelian susceptibility to atypical mycobacteria


  • Meningioma

    2 members

    Meningiomas are the most common benign tumors of the brain.

  • Menkes Syndrome

    2 members

    Menkes syndrome is an inborn error of metabolism in which cells in the body cannot absorb enough copper.

  • MEPAN Syndrome

    1 members

    MEPAN Syndrome is an ultra-rare neurodegenerative mitochondrial condition that is caused by mutations to the MECR gene. It results in impaired mitochondrial fatty acid synthesis and causes child...

  • MERRF Syndrome

    1 members

    MERRF Syndrome is a rare disorder that affects the function of the mitochondria.

  • Metachromatic Leukodystrophy

    6 members

    Metachromatic Leukodystrophy is a rare lysosomal storage disease.

  • Metaphyseal Dysplasia

    4 members

    Metaphyseal Dysplasia is s a rare disorder in which the outer part of the shafts of long bones is unusually thin with a tendency to fracture.

  • Methylenetetrahydrofolate Reductase Deficiency

    11 members

    Methylenetetrahydrofolate Reductase Deficiency (MTHFR) is a rare blood disorder and caused by mutations resulting in decreased enzyme activity.

  • Microduplication 22q11.2 Syndrome

    58 members

    Microduplication 22q11.2 syndrome is caused by an extra copy of a small piece of chromosome 22 at location q11.2.

  • Microscopic Polyangiitis

    4 members

    Microscopic Polyangiitis is a rare autoimmune disease. This disease can affect many of the body's organ systems including (but not limited to) the kidneys, nervous system (particularly the peripher...

  • Miller-Dieker Syndrome

    3 members

    Miller-Dieker Syndrome (MDS) is a rare genetic condition, characterized by an abnormally smooth brain (lissencephaly), distinctive facial features, and neurologic abnormalities. MDS is caused by...

  • Minicore Myopathy

    5 members

    Minicore Myopathy is characterized by multiple small areas of disruption in the muscle.

  • Minimal Change Disease

    5 members

    Minimal Change Disease is a disease of the kidney usually affecting children.

  • Mitochondrial Diseases

    28 members

    Mitochondrial Diseases are a group of rare disorders relating to the mitochondria.

  • Mixed Connective Tissue Disease

    40 members

    Mixed connective tissue disease (MCTD) is an autoimmune disorder that manifests symptoms from oth...

  • Moebius Syndrome

    6 members

    Moebius Syndrome is a rare congenital neurological disorder characterized by facial paralysis and the inability to move the eyes from side to side.

  • Molybdenum Cofactor Deficiency

    1 members

    Molybdenum cofactor deficiency is a rare disorder characterized by progressive neurological deterioration. This condition is caused by genetic defects that lead to a reduction in the s...

  • Monomelic Amyotrophy

    4 members

    Monomelic Amyotrophy is a rare lower motor neuron disorder that primarily affects young adult males in India and Japan.

  • Monosomy 21

    3 members

    Monosomy 21 is a rare disorder in which the 21st chromosome is missing from what should be a pair in every cell throughout the body.

  • Monosomy 9p

    1 members

    Monosomy 9p is a rare disorder with the deletion of a portion of chromosome 9.

  • Morgellons

    52 members

    Morgellons is a condition characterized by a range of symptoms including crawling, biting, and stinging sensations on the skin; finding fibers on or under the skin; and persistent rashes or sores.

  • Morquio Syndrome

    3 members

    Morquio Syndrome is a rare mucopolysaccharide storage disorder.

  • mosaic variegated aneuploidy (MVA)

    1 members

    Mosaic variegated aneuploidy (MVA) syndrome is a very rare condition characterized by problems with celldivision (specifically during mitosis) that...

  • Moyamoya Disease

    37 members

  • MPPH Syndrome

    39 members

    MPPH (Magalencephaly, Polymicrogyria, Prodadactyly & Hydromcephalus) Syndrome.

  • Muckle-Wells Syndrome

    108 members

    Muckle-Wells syndrome (MWS) is an hereditary autoinflammatory disease with periodic fevers caused by mutations in the NLRP3 gene. It is considered a cryopyrin-associated syndrome (CAPS)...

  • Mucolipidosis Type 2

    2 members

  • Muenke Syndrome

    2 members

    Muenke Syndrome is a disorder characterized by the premature closure of bones of the skull during development.

  • Multicentric Reticulohistiocytosis

    6 members

    Multicentric Reticulohistiocytosis is a rare disorder characterized by the proliferation of immune cells, causing arthritis and skin nodules.

  • Multifocal Motor Neuropathy with Conduction Block

    9 members

    Multifocal Motor Neuropathy with Conduction Block is a rare disorder causing the destruction of the protective sheath around nerves.

  • Multiple Endocrine Neoplasia Type 1

    7 members

    Multiple endocrine neoplasia type 1 is a disorder in which multiple endocrine glands become overactive at the same time.

  • Multiple Endocrine Neoplasia Type 2A


    Multiple Endocrine Neoplasia Type 2A is a is hereditary syndrome characterized by medullary carcinoma of the thyroid, pheochromocytoma, hyperparathyroidism and occasionally cutaneous lichen amyloid...

  • Multiple Endocrine Neoplasia Type 2B

    3 members

    Multiple endocrine neoplasia, Type 2B is a rare familial cancer syndrome caused by mutations in the RET proto-oncogene.

  • Multiple Epiphyseal Dysplasia

    11 members

    Multiple Epiphyseal Dysplasia is a rare cartilage and bone disorder.

  • Multiple Intestinal Lipomatosis


    Multiple Intestinal Lipomatosis is a rare disorder characterized by benign tumors in the intestinal tract.

  • Multiple Myeloma

    17 members

    Multiple Myeloma is a rare type of cancer of plasma cells. It is also known as bone marrow cancer or as one of the blood cancers.

  • Multiple Pterygium Syndrome

    1 members

    Multiple Pterygium Syndrome is a rare genetic disorder characterized by facial anomalies, short stature, vertebral defects, and webbing of the neck, inside bend of the elbows, back of the knees, ar...

  • Multiple Sclerosis

    26 members

    Multiple sclerosis (MS) is a neurological, autoimmune disorder of the central nervous system.  The immune system is the body’s defense against foreign materials such as viru...

  • Multiple System Atrophy

    12 members

    Multiple System Atrophy is a rare neurodegenerative disease caused by cell loss in the brain imparing the autonomic nervous system and the motor system.

  • Multisystem Proteinopathy (MSP)

    4 members

    Multisystem proteinopathy (MSP) is an inherited degenerative disorder that affects multiple organ systems including the muscle, bone and the nervous system. The phenotypes of MSP encompass inclu...

  • MURCS Association


    MURCS Association is a rare disorder that affects females. MURCS stands for Mullerian, Renal, Cervicothoracic Somite abnormalities.

  • Muscle-Eye-Brain Disease

    2 members

    Congenital musclar dystrophy, severe myopia, brain involvement is "cobblestone" cortex with mental retardation and many other brain deformities.

  • Muscular Dystrophy, Duchenne and Becker Types

    18 members

    Duchenne and Becker Muscular Dystrophy is a genetic condition characterized by progressive muscle weakness and atrophy which primarily affects the skeletal and heart muscles.

  • Myasthenia Gravis

    16 members

    Myasthenia Gravis is an autoimmune disease causing muscle weakness and muscle fatigue in specific muscles, such as eye muscles, or in multiple muscle groups, also known as the generalized form. ...

  • Mycobacterium Avium Complex

    1 members

    Mycobacterium avium complex (MAC) is a group of genetically related bacteria belonging to the genus Mycobacterium. It includes Mycobacterium avium and Mycobacterium intracellulare.

  • Mycobacterium Kansasii Olecranon Bursitis


    Mycobacterium Kansasii Olecranon Bursitis is a condition characterised by pain, swelling and inflammation of the olecranon bursa in the elbow caused by the bacterium mycobacterium kansasii.

  • Mycosis Fungoides

    4 members

    Mycosis Fungoides is a rare form of cutaneous T-cell lymphoma (Non-Hodgkin lymphoma).

  • Myelodysplastic Syndromes

    5 members

    Myelodysplastic syndrome (MDS) is a group of cancers affecting blood cells. The term “myelodysplastic” comes from “myelo,” meaning marrow, and “dysplasia&...

  • Myelofibrosis with Myeloid Metaplasia

    7 members

    There are three main types of cells in blood: red blood cells (RBCs), white blood cells (WBCs), and platelets. RBCs are responsible for the transport of gases such as oxygen and carbon...

  • Myoadenylate Deaminase Deficiency

    2 members

    Myoadenylate Deaminase Deficiency is a recessive genetic metabolic disorder characterized by the failure to deaminate the AMP molecules.

  • Myoclonus-Dystonia

    8 members

    Myoclonus-Dystonia is a rare movement disorder characterized by rapid, brief muscle contractions and/or sustained twisting and repetitive movements that result in abnormal postures.

  • Myotonic Dystrophy Type 1

    3 members

  • Myotubular Myopathy

    4 members

    Myotubular Myopathy is a rare genetic disorder causing low muscle tone in the voluntary muscles.