Megalencephaly - cutis marmorata telangiectatica congenita: A very rare syndrome characterized mainly by an enlarged brain, neurological abnormalities and a blood vessel abnormality that gives the skin a marbled appearance.
Megalencephaly - polymicrogyria - post-axial polydactyly - hydrocephalus: A rare syndrome characterized mainly by brain abnormalities, extra digits and a excess fluid inside the skull.
Megaloblastic (pernicious) anemia is a rare disorder in which the body does not absorb enough vitamin B12 from the digestive tract, resulting in an inadequate amount of red blood cells (RBCs) produced.
Megalocornea mental retardation syndrome: A very rare genetic disorder characterized by reduced muscle tone from birth, mental retardation to varying degrees and eye abnormalities. The type and severity of symptoms is variable.
Megarbane syndrome: A very rare disorder characterized by short stature, loose joints, hernias, facial abnormalities and severe psychomotor retardation.
Mehes syndrome: A very rare syndrome characterized mainly by delayed speech, an asymmetrical face, crossed eyes and ear lobe creases.
Mehta Lewis Patton syndrome (medical condition): A rare birth syndrome characterized by heart disease, droopy eyelids, missing teeth and premature fusion of skull bones.
Meier-Blumberg-Imahorn syndrome: A very rare syndrome characterized mainly by high urine calcium level and eye problems
Meier-Rotschild syndrome: A rare disorder characterized mainly by short stature, small ears and absent kneecaps.
Meige's syndrome is a type of dystonia. It is also known as oral facial dystonia. It is actually a combination of two forms of dystonia, blepharospasm and oromandibular dystonia (OMD).
Meinecke pepper syndrome (medical condition): A very rare syndrome characterized mainly by short arms, facial anomalies and various other abnormalities.
Meinecke syndrome: A very rare syndrome characterized mainly by mental retardation and short broad thumbs.
Melanoma - astrocytoma syndrome: A rare syndrome characterized by the association of a melanoma with a type of brain tumor called an astrocytoma. The exact symptoms may vary depending on the exact location of the brain tumor. More detailed inform
Melanoma of the choroid: A type of eye cancer that occurs in the pigment-producing cells of the choroid which is a layer beneath the retina consisting mainly of blood vessels.
Malignant melanoma that originates in the ciliary body is termed, "ciliary body melanoma." The ciliary body is located immediately behind the iris and in front of the choroid. Therefore, it is hidden behind the iris. It is responsible for making the aqueous fluid that fills the front of the eye. The ciliary body is highly vascular and contains the melanocytes from which melanomas can grow. Compared to iris and choroidal melanoma, ciliary body melanoma is the most difficult to find.
The iris is the colored part of the eye. It is made up of two layers. The outer "stroma" can be blue, hazel, green or brown. The back layer (the iris pigment epithelium) is always brown. Tumors can grow within and behind the iris. Though most iris tumors are cysts or nevi, malignant melanomas can also occur in the iris.
Meleda Disease: A very rare inherited skin disorder primarily involving dry thick skin patches that develop on the palms of hands and soles of feet. The type and severity of symptoms is variable.
Melhem-Fahl syndrome: A very rare syndrome
Melioidosis is an infectious disease caused by a gram-negative bacterium, Burkholderia pseudomallei, found in soil and water. It is of public health importance in endemic areas, particularly in Thailand and northern Australia. It exists in acute and chronic forms. Signs and symptoms may include pain in chest, bones, or joints; cough; skin infections, lung nodules and pneumonia.
B. pseudomallei was previously classed as part of the Pseudomonas genus and until 1992, it was known as Pseudomonas pseudomallei. It is phylogenetically related closely to Burkholderia mallei which causes glanders, an infection primarily of horses, donkeys, and mules. The name melioidosis is derived from the Greek melis (μηλις) meaning "a distemper of asses" with the suffixes -oid meaning "similar to" and -osis meaning "a condition", that is, a condition similar to glanders.
Melkersson-Rosenthal syndrome is a rare neurological disorder characterized by recurring facial paralysis, swelling of the face and lips (usually the upper lip), and the development of folds and furrows in the tongue. Onset is in childhood or early adolescence. After recurrent attacks (ranging from days to years in between), swelling may persist and increase, eventually becoming permanent. The lip may become hard, cracked, and fissured with a reddish-brown discoloration. The cause of Melkersson-Rosenthal syndrome is unknown, but there may be a genetic predisposition. It can be symptomatic of Crohn's disease or sarcoidosis.
This rare genetic syndrome is best described in females, with a small number of severely affected males also reported.
Melorheostosis: A rare bone condition that usually begins in childhood characterized by thickening of the bones (sclerosis) of a limb. Pain is frequent in the involved limb. The affected bone can have the appearance of "dripping candle wax" when visualized with X-ray imaging.
Membranoproliferative glomerulonephritis (GN) type II is a kidney disorder causing decreased kidney function because of inflammation and changes in the tissues of the internal kidney structures.
A disease of the glomerulus manifested clinically by proteinuria, and sometimes by other features of the nephrotic syndrome. It is histologically characterized by deposits in the glomerular capillary wall between the epithelial cell and the basement membrane and a thickening of the membrane. Also characteristic are outward projections of the membrane between the epithelial deposits in the form of "spikes". There is some agreement that the deposits are antigen-antibody complexes.
Myoclonic epilepsy myopathy sensory ataxia (MEMSA) is a disease which starts in childhood to late adulthood. The symptoms include problems in movement coordination, seizures and uncontrollable muscle jerks as well as a degeneration of muscles and brain dysfunctions. The disease itself is caused by a mutation in the DNA of mitochondria, which leads to a lower energy supply in the cells of the body. Treatment of MEMSA is largely supportive, including physiotherapy, speech therapy and seizure management.
Other names: Spinocerebellar ataxia with epilepsy (SCAE)
Sources: Genetics Home Reference (NIH), GeneReviews
Mendelian susceptibility to atypical mycobacteria: A very rare group of disorders where a person without an immune deficiency is susceptible to infection by weak mycobacterial organisms, nontuberculous and environmental mycobacteria e.g. Calmette-Guerin Bacillus (BCG). The severity of the disorder is greatly variable and ranges from a localized recurring non-tuberculous mycobacterial infection to a potentially fatal BCG infection. Most people who are infected with these organisms have no symptoms but a genetic mutation in some people makes them more susceptible.
Ménétrier disease causes the ridges along the inside of the stomach wall—called rugae—to enlarge, forming giant folds in the lining of the stomach. The rugae enlarge because of an overgrowth of surface mucous cells of the stomach. In a normal stomach, rugae release protein-containing mucus. Enlarged rugae release too much mucus, causing a leakage of protein from the blood into the stomach. This shortage of protein in the blood is known as hypoproteinemia. Ménétrier disease also causes a decrease in stomach acid resulting from a reduction in acid-producing parietal cells.
Mengel Konigsmark syndrome (medical condition): A rare disorder characterized by hearing loss and external ear malformations.