Human health and medicine

Megacystis-microcolon-intestinal hypoperistalsis syndrome

MMIHS, or Berdon syndrome, is a rare congenital smooth muscle disorder causing megacystis, microcolon, and absent intestinal peristalsis, usually from autosomal dominant de novo ACTG2 mutations, managed with parenteral nutrition and transplantation.

Megalencephalic leukoencephalopathy with subcortical cysts

Megalencephalic leukoencephalopathy with subcortical cysts (MLC, Van der Knaap disease) is a rare leukodystrophy with infantile macrocephaly, swollen white matter, anterior temporal cysts, and genes MLC1, GLIALCAM, GPRC5B, AQP4.

Megalencephaly-capillary malformation-polymicrogyria syndrome

Megalencephaly-capillary malformation-polymicrogyria syndrome (MCAP, M-CM, OMIM 602501) is a rare PIK3CA-mosaic overgrowth disorder with megalencephaly, polymicrogyria, and cutaneous capillary malformations, sporadic, present at birth.

Megalencephaly-polymicrogyria-postaxial polydactyly-hydrocephalus syndrome

MPPH syndrome, also called megalencephaly-polymicrogyria-polydactyly-hydrocephalus syndrome, is a rare autosomal dominant brain overgrowth disorder caused by AKT3, CCND2, or PIK3R2 gain-of-function variants in the PI3K-AKT-mTOR pathway, with polymicrogyria, hydrocephalus, and postaxial polydactyly.

Megaloappendix

Megaloappendix (ICD-11 DB11.0) is an abnormally long, enlarged vermiform appendix; the largest removed measured 55 cm in a 2011 Qatari case report, versus a 6–9 cm normal average.

Megaloblastic anaemia due to vitamin B12 deficiency

Megaloblastic anaemia due to vitamin B12 deficiency (ICD-11 3A01), also called cobalamin deficiency anaemia or Addison anaemia: impaired DNA synthesis from low B12 causes macrocytic anaemia, elevated MMA and homocysteine, and neurological damage; pernicious anaemia is the leading cause.

Megaloblastic anemia

Megaloblastic anemia, a macrocytic anemia from defective DNA synthesis, usually caused by vitamin B12 or folate deficiency; pernicious anemia is the leading B12 cause, with macro-ovalocytes and hypersegmented neutrophils on smear.

Megalocornea-intellectual disability syndrome

Megalocornea-intellectual disability syndrome, also called MMR or Neuhäuser syndrome (OMIM 249310), is an extremely rare autosomal recessive disorder combining enlarged corneas without glaucoma, hypotonia, intellectual disability, seizures, and facial dysmorphism, with about 40 reported cases and unknown genetic cause.

MEGDEL syndrome

MEGDEL syndrome (MEGDHEL), a rare autosomal recessive SERAC1-related neurometabolic disorder with 3-methylglutaconic aciduria, neonatal hepatopathy, hypotonia, dystonia, spasticity, progressive deafness, and Leigh-like brain changes.

Mehamudgara Rasa

Mehamudgara rasa (Meha Mudgara Rasa, MMR), a classical Ayurvedic herbo-mineral formulation from Bhaishajya Ratanavali for Prameha (diabetes); contains Triphala, Trikatu, guggulu, Lauha bhasma and other ingredients, 500 mg dose, studied via HPTLC and a 94-patient type 2 diabetes trial.

Mehmet Oz

Mehmet Cengiz Oz (born 1960, Cleveland, Ohio) is an American cardiothoracic surgeon, host of The Dr. Oz Show (2009-2022), 2022 Pennsylvania Senate candidate, and 17th CMS Administrator confirmed April 2025.

MEHMO syndrome

MEHMO syndrome (OMIM 300148), also called X-linked intellectual disability-epileptic seizures-hypogenitalism-microcephaly-obesity syndrome, is an ultra-rare X-linked recessive EIF2S3 disorder affecting males, with intellectual disability, epilepsy, hypogonadism, microcephaly, obesity, and diabetes.

Sep 29, 2026

Meibography

Meibography is an infrared imaging technique that photographs the meibomian glands inside the everted eyelids to detect gland loss in meibomian gland dysfunction and dry eye.

Meibomian gland

Meibomian gland (tarsal gland): large modified sebaceous gland in the eyelid tarsal plate, described by Heinrich Meibom in 1666, secreting meibum holocrinely to form the tear film's lipid layer; its dysfunction (MGD) causes most evaporative dry eye.

Meibomian gland dysfunction

Meibomian gland dysfunction (MGD), chronic obstruction or secretion abnormality of the eyelid oil glands, is the leading cause of evaporative dry eye; pooled prevalence about 36%, treated with warm compresses, antimicrobials, and thermal pulsation devices.

Meige disease

Meige disease, also called lymphedema praecox or hereditary lymphedema II, is a hereditary primary lymphedema causing painless swelling of the legs that usually begins at puberty.

Meigs syndrome

Meigs syndrome (Demons-Meigs syndrome): benign ovarian tumor, usually fibroma, with ascites and pleural effusion that resolve after tumor removal; named for Joe Vincent Meigs, 1937.

Meisoindigo

Meisoindigo (甲异靛, N-methylisoindigotin, Dian III) is a synthetic indirubin derivative approved in China in 1992 for chronic myeloid leukemia; dosed 50 mg two to three times daily, it induces apoptosis and differentiation and acts as a PKMYT1 molecular glue.

Melaena

Melaena (melena), ICD-11 ME24.A4 / ICD-10 K92.1, is the passage of black, tarry, foul-smelling stools from digested blood, usually signaling upper GI bleeding above the ligament of Treitz, distinct from iron- or bismuth-stained black stool.

Melagatran

Melagatran: active metabolite of the prodrug ximelagatran (Exanta), AstraZeneca's first oral direct thrombin inhibitor; approved in the EU in 2004 for orthopedic VTE prophylaxis, withdrawn worldwide in February 2006 for hepatotoxicity.

Melancholia

Melancholia, also called melancholic depression or MDD with melancholic features, is a severe depressive syndrome marked by anhedonia, mood nonreactivity, and psychomotor disturbance; historically attributed to black bile, now a DSM-5 specifier with distinct treatment response.

Oct 15, 2026

Melanin-concentrating hormone

Melanin-concentrating hormone (MCH) is a cyclic neuropeptide produced mainly in the hypothalamus that regulates feeding behavior, metabolism, and sleep-wake rhythms, and is a target for obesity drugs.

Melanocyte stimulating hormone secreting cell

Melanocyte stimulating hormone secreting cell, also called melanotrope or melanotroph, is the POMC-expressing endocrine cell of the pituitary intermediate lobe that secretes alpha-MSH and beta-endorphin under dopaminergic control.

Melanocytic nevus

Melanocytic nevus (mole, pigmented nevus): benign skin lesion from local melanocyte proliferation, congenital (about 1% of births) or acquired; BRAF/NRAS driver mutations, very low per-mole melanoma transformation risk, ABCD warning signs.

Melanoma

Melanoma, also called malignant melanoma, is a cancer of melanocytes, the pigment cells of the skin, eye, or mucosa; defined by ABCDE warning signs, BRAF mutations in about 60% of cases, and modern checkpoint-inhibitor and targeted therapy.

Melanoma and neural system tumor syndrome

Melanoma and neural system tumor syndrome (melanoma-astrocytoma syndrome, ORPHA:252206, OMIM 155755) is an extremely rare autosomal dominant CDKN2A (9p21.3) predisposition syndrome combining cutaneous melanoma and neural tumors, typically astrocytoma.

Melanoma associated retinopathy

Melanoma associated retinopathy (MAR), ICD-11 9B71.40, is a rare paraneoplastic retinopathy of metastatic melanoma caused by TRPM1 autoantibodies against retinal ON-bipolar cells, causing night blindness, photopsias, field loss, and an electronegative ERG.