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Dyslexia
Dyslexia is a neurodevelopmental learning disability affecting word reading and spelling, first named by Rudolf Berlin in the 1880s; prevalence estimates range from 5 to 17.5 percent, with phonological processing deficits as the leading marker.
Dyslexia or alexia
Dyslexia or alexia (ICD-11 MB4B.0) is the acquired loss, usually in adulthood after stroke or brain injury, of previously fluent reading and comprehension, distinct from developmental dyslexia; syndromes include pure, surface, phonological, and deep dyslexia.
Dyslipidemia
Dyslipidemia: abnormal blood lipid levels (high cholesterol, high triglycerides, high Lp(a), or low HDL-C), also called hyperlipidemia. Causes are genetic or secondary; treatment is lifestyle plus statins, guided by 2026 ACC/AHA PREVENT-based risk thresholds and LDL-C goals.
Dysmenorrhea
Dysmenorrhea, or painful menstrual periods, affects 50–90% of young women. Primary dysmenorrhea (about 90% of cases) stems from uterine prostaglandins; secondary forms arise from endometriosis, adenomyosis, or other pelvic pathology. NSAIDs and hormonal contraceptives are first-line treatments.
Dysmenorrhoea
Dysmenorrhoea, or dysmenorrhea, is painful menstruation, classified as primary (no pelvic pathology) or secondary (caused by conditions such as endometriosis). Prostaglandin-driven uterine hypercontractility causes the pain; NSAIDs and combined oral contraceptives are first-line treatments.
Dysosteosclerosis
Dysosteosclerosis (DSS, DOS; OMIM 224300) is an ultrarare genetic bone dysplasia with progressive osteosclerosis and platyspondyly, an osteoclast-poor osteopetrosis-like disorder linked to SLC29A3, TNFRSF11A, TCIRG1, LRRK1, and CSF1R, with fewer than 30 reported cases.
Dyspareunia
Dyspareunia is recurrent pain with vaginal intercourse, superficial (introital) or deep, affecting up to 3 of 4 women at some point; causes include vulvodynia, endometriosis, and menopausal atrophy.
Dysphagia
Dysphagia, difficulty swallowing, is classified as oropharyngeal or esophageal. Prevalence 10–20%; linked to stroke pneumonia risk (RR 3.17); assessed by VFSS, FEES, endoscopy, and manometry.
Dysphagia lusoria
Dysphagia lusoria (Bayford syndrome) is difficulty swallowing from esophageal compression by an aberrant right subclavian artery, a congenital aortic arch anomaly in 0.5-2.5% of people, mostly asymptomatic.
Dysphagia screening
Dysphagia screening is a rapid bedside pass/fail procedure, standard in acute stroke care, that identifies patients at risk of swallowing difficulty before any oral intake.
Dysphania ambrosioides
Dysphania ambrosioides, known as epazote or Mexican tea, is an aromatic herb native to the Americas, used as a culinary herb in Mexican and Caribbean cooking and in traditional medicine against intestinal parasites.
Dysphonia
Dysphonia (hoarseness): altered voice quality, pitch, loudness, or effort impairing communication; affects about one-third of people. Causes include laryngitis, reflux, lesions, and laryngeal dystonia; voice therapy is first-line.
Dysphoria
Dysphoria (Greek dysphoria, 'hard to bear') is a mood of generalized discontent, agitation and unease, not a standalone diagnosis. It appears across PMDD, gender dysphoria, mixed bipolar states, and epilepsy, measured with scales such as the UGDS, IDDI, and DRSP.
Dysplasia
Dysplasia: abnormal cells in a tissue or organ, not cancer but sometimes precancerous; graded mild, moderate, or severe. Also means birth-related developmental disorders of skin, brain, cartilage, or bone.
Dysplastic cortical hyperostosis
Dysplastic cortical hyperostosis (ORPHA:646139), also called Kozlowski-Tsuruta type, is an extremely rare autosomal recessive bone dysplasia causing lethal neonatal dwarfism with hydrops and generalized cortical thickening of the skeleton; molecular basis unknown.
Dyspnoea
Dyspnoea (dyspnea, breathlessness, shortness of breath) is the subjective experience of breathing discomfort, distinct from tachypnea or hyperventilation. Common in cardiopulmonary disease, coded ICD-11 MD11.5, measured by MRC, Borg, D-12, and MDP scales.
Dyssegmental dysplasia, Silverman-Handmaker type
Dyssegmental dysplasia, Silverman-Handmaker type (DDSH, MIM 224410), also called lethal Kniest-like syndrome, is a lethal autosomal recessive skeletal dysplasia from HSPG2 (perlecan) null mutations, marked by anisospondyly, micromelia, and neonatal death.
Dyssomnia
Dyssomnia: umbrella term for sleep disorders affecting the amount, quality, or timing of sleep, including insomnia, hypersomnia, narcolepsy, and sleep apnea; a DSM-IV-TR and ICSD category retired in DSM-5 and ICSD-2/3 in favor of sleep-wake disorders.
Dysspondyloenchondromatosis
Dysspondyloenchondromatosis (DSC), enchondromatosis type V, is a rare non-hereditary skeletal disorder combining multiple enchondromas with irregular vertebral malformations (anisospondyly), short stature, scoliosis, and joint deformities.
Dysthymia
Dysthymia, now persistent depressive disorder (PDD), is chronic mild depression lasting two years or more; DSM-5-TR dropped the dysthymia label; US past-year prevalence 1.5%, lifetime 2.5%.
Dysthyroid orbitopathy
Dysthyroid orbitopathy, also called thyroid eye disease or Graves' orbitopathy, is an autoimmune orbital disorder driven by TSHR and IGF-1R antibodies, causing proptosis, diplopia, and sometimes dysthyroid optic neuropathy, treated by glucocorticoids, biologics, and surgery.
Dystonia
Dystonia, also known as dystonic disorders or distonia, is a movement disorder causing repetitive abnormal postures and movements, the third most common movement disorder after Parkinson's disease and essential tremor.
Dystonia 16
Dystonia 16, formally DYT-PRKRA, is a rare autosomal recessive dystonia caused by PRKRA gene variants, beginning in childhood, often in a limb, with prominent laryngeal involvement.
Dystonia 28
Dystonia 28 (DYT28, DYT-KMT2B) is a rare autosomal dominant dystonia caused by heterozygous KMT2B variants or 19q13.12 deletions, starting in childhood with lower-limb dystonia that generalizes, with developmental delay and response to anticholinergics and GPi DBS.
Dystonia-plus
Dystonia-plus is a category of movement disorders in which dystonia occurs with other neurological features such as myoclonus or parkinsonism, without neurodegeneration; its three main syndromes are dopa-responsive dystonia, myoclonus-dystonia, and rapid-onset dystonia-parkinsonism.
Dystroglycan-type cadherin-like
Dystroglycan-type cadherin-like (CADG) domain: a cadherin-homologous extracellular protein domain in metazoan dystroglycan and α/ε-sarcoglycan, yeast Axl2p, and large bacterial proteins; identified in 2002; LGMD2D mutations cluster in the α-sarcoglycan copy.
Dystrophic epidermolysis bullosa pruriginosa
Dystrophic epidermolysis bullosa pruriginosa (DEB-Pr, EBP, OMIM 604129) is a rare COL7A1-driven subtype of dystrophic epidermolysis bullosa marked by intense pruritus, prurigo-like nodules on extensor limbs, nail dystrophy, and delayed adult onset.
Dystrophinopathy
Dystrophinopathy: spectrum of DMD gene disorders including Duchenne muscular dystrophy, Becker muscular dystrophy, and DMD-related dilated cardiomyopathy; X-linked, 1 in 3,600 male births, reading-frame rule with exceptions.
Dysuria
Dysuria is painful or burning urination, usually from lower urinary tract infection, most often cystitis or STI urethritis; also caused by irritants, stones, atrophic vaginitis, interstitial cystitis, and tumors.
Dytiscidae
Dytiscidae, predaceous diving beetles (Leach, 1815), the largest aquatic beetle family with over 4,600 species worldwide; aquatic predatory adults and larvae, air stored under elytra, sister family Hygrobiidae.