25,729 articles
Asymptomatic carrier
Asymptomatic carrier: a person harboring an infectious agent without symptoms who can transmit it. Covers carrier types, Typhoid Mary, and SARS-CoV-2 evidence showing lower but real carrier transmission.
Asystole
Asystole (cardiac standstill, flatline) is the absence of cardiac electrical activity on ECG during cardiac arrest. A nonshockable rhythm with PEA; treated with CPR and early epinephrine, not defibrillation or pacing.
AT regimen (chemotherapy)
The AT regimen is a combination chemotherapy of doxorubicin plus a taxane, docetaxel or paclitaxel, given on the same day, mainly to treat breast cancer.
ATACH-II trial
ATACH-II (Antihypertensive Treatment of Acute Cerebral Hemorrhage II), NCT01176565, was a phase III trial of 1,000 ICH patients testing SBP 110-139 vs 140-179 mm Hg with nicardipine; stopped for futility, no outcome benefit, more renal adverse events.
Atacicept
Atacicept is a wholly human TACI-IgG1 fusion protein that blocks BAFF and APRIL; it failed in lupus, rheumatoid arthritis, and multiple sclerosis trials but met its endpoints in IgA nephropathy.
AtaiBeckley
AtaiBeckley (AtaiBeckley Inc., formerly ATAI Life Sciences) is a New York-based clinical-stage biotech formed in 2025 by the atai–Beckley Psytech merger, developing psychedelic neuroplastogens led by BPL-003 intranasal 5-MeO-DMT for treatment-resistant depression; acquired by Eli Lilly in 2026 for up to $3.8 billion.
Ataluren
Ataluren (PTC124, Translarna), an oxadiazole small molecule meant to read through premature stop codons in nonsense mutations; conditionally approved in the EU in 2014 for nonsense-mutation DMD, never FDA-approved, and its EU authorisation was not renewed in March 2025 after efficacy doubts.
Atamestane
Atamestane (SH-489, 1-methyl-1,4-androstadiene-3,17-dione) is an investigational steroidal aromatase inhibitor developed by Schering AG; BPH trials showed no benefit over placebo and its phase III breast cancer trial matched but did not beat letrozole.
Ataxia
Ataxia is poor muscle control causing clumsy movement, usually from cerebellar damage; it spans hereditary forms (SCAs, Friedreich ataxia, ataxia-telangiectasia), acquired causes, and new drug approvals.
Ataxia-hypogonadism-choroidal dystrophy syndrome
Ataxia-hypogonadism-choroidal dystrophy syndrome, or Boucher-Neuhäuser syndrome (BNS), is a rare autosomal recessive PNPLA6-related neurodegenerative disorder combining cerebellar ataxia, chorioretinal dystrophy, and hypogonadotropic hypogonadism, with onset from 1 to 40 years.
Ataxia-intellectual disability-oculomotor apraxia-cerebellar cysts syndrome
Ataxia-intellectual disability-oculomotor apraxia-cerebellar cysts syndrome, or Poretti-Boltshauser syndrome (ORPHA:370022, OMIM 615960), is a rare autosomal recessive LAMA1-related disorder with nonprogressive cerebellar ataxia, intellectual disability, ocular motor apraxia, high myopia, and cerebellar dysplasia with cysts on MRI.
Ataxia-oculomotor apraxia type 1
Ataxia-oculomotor apraxia type 1 (AOA1, EAOH) is a rare autosomal recessive cerebellar ataxia caused by APTX mutations, with childhood-onset ataxia, oculomotor apraxia, neuropathy, hypoalbuminemia, and hypercholesterolemia.
Ataxia-oculomotor apraxia type 4
Ataxia-oculomotor apraxia type 4 (AOA4), PNKP-related ataxia, is a rare autosomal recessive cerebellar ataxia with dystonia, oculomotor apraxia, and polyneuropathy beginning around age 4, causing wheelchair dependence by the third decade.
Ataxia-pancytopenia syndrome
Ataxia-pancytopenia syndrome (ATXPC, myelocerebellar disorder, OMIM 159550) is a rare autosomal dominant disease caused by germline gain-of-function SAMD9L mutations, combining cerebellar ataxia, cytopenias, and predisposition to MDS and AML with monosomy 7.
Ataxia-telangiectasia
Ataxia-telangiectasia (A-T, Louis-Bar syndrome) is a rare autosomal recessive multisystem disorder caused by biallelic ATM gene variants, marked by progressive cerebellar ataxia, telangiectasia, immunodeficiency, radiosensitivity, and cancer predisposition.
Ataxia-telangiectasia variant
Ataxia-telangiectasia variant is a rare genetic movement disorder caused by ATM gene mutations, resembling ataxia-telangiectasia but with adult onset, slower progression, and an extended lifespan.
Ataxia-telangiectasia-like disorder
Ataxia-telangiectasia-like disorder (ATLD, OMIM 604391): rare autosomal recessive chromosomal instability syndrome with progressive cerebellar ataxia, oculomotor apraxia, and radiosensitivity but no telangiectasia; ATLD1 from MRE11A mutations, ATLD2 from PCNA mutations.
Ataxic breathing
Ataxic breathing (Biot's respiration, respiratory ataxia), ICD-11 MD11.2: a completely irregular breathing pattern with variable rate and depth and unpredictable apneic pauses, usually progressing to apnoea; caused by medullary and lower brainstem lesions, meningitis, raised intracranial pressure, or opioids.
Ataxic cerebral palsy
Ataxic cerebral palsy (ICD-11 8D22, ICD-10 G80.4) is the least common CP subtype, dominated by cerebellar signs: ataxia, hypotonia, dysmetria, dysarthria, nystagmus; about 3.8% of cases, often genetic origin.
Ataxic disorders
Ataxic disorders (ICD-11 8A03) are conditions causing loss of coordination from cerebellar, sensory, or vestibular damage, spanning hereditary ataxias such as Friedreich ataxia and over 40 spinocerebellar ataxias, acquired causes like stroke and alcohol, and sporadic idiopathic forms.
Ataxic gait
Ataxic gait (staggering gait; ICD-10 R26.0, ICD-11 MB44.0) is an unsteady, wide-based, highly variable walking pattern from cerebellar, sensory, vestibular, or functional causes, rated by SARA and related scales.
ATB102, aryl hydrocarbon receptor (AhR) agonist for ulcerative colitis
ATB102 (YUQ-A1007) is Allianthera's oral, gut-enriched aryl hydrocarbon receptor agonist in phase 1 trials for refractory moderate-to-severe ulcerative colitis; Dr. Falk Pharma licensed worldwide rights in July 2025, excluding Greater China.
Atelectasis
Atelectasis, or partial lung collapse, is reversible loss of lung volume from airway obstruction, compression, hypoventilation, or surfactant impairment; common after anesthesia, diagnosed by chest x-ray or CT, treated with lung expansion and cause-directed care.
Atelosteogenesis type I
Boomerang dysplasia (OMIM 112310), a perinatal-lethal FLNB-related skeletal dysplasia with short-limbed dwarfism, joint dislocations, and boomerang-shaped long bones, now subsumed under atelosteogenesis type 1.
Atelosteogenesis type II
Atelosteogenesis type II (AO2, De la Chapelle dysplasia) is a lethal perinatal skeletal dysplasia from SLC26A2 (DTDST) mutations, autosomal recessive, with limb shortening, cleft palate, hitchhiker thumbs, and respiratory failure at birth.
Atelosteogenesis type III
Atelosteogenesis type III (AO3, AOIII) is a rare autosomal dominant skeletal dysplasia from FLNB gain-of-function mutations, with joint dislocations, short limbs, airway malacia, and fewer than 25 reported cases.
Atencion primaria
Atencion primaria (Atención Primaria) is a Spanish peer-reviewed family medicine journal, ISSN 0212-6567/1578-1275, founded 1983, published by Elsevier España for semFYC and indexed in MEDLINE and Scopus.
Atenolol
Atenolol (Tenormin, ICI 66,082) is a beta1-selective beta-blocker approved in the US in 1981 for hypertension, angina, and acute myocardial infarction; renal excretion, 6-7 hour half-life, ISIS-1 mortality benefit.
Atezolizumab
Atezolizumab (Tecentriq, Tecentriq Hybreza, MPDL3280A) is Roche's Fc-engineered anti-PD-L1 IgG1 antibody for NSCLC, SCLC, HCC and urothelial carcinoma, with IV dosing 840-1,680 mg and a 2024 subcutaneous formulation.
Atezolizumab regimen
An atezolizumab regimen is a cancer treatment schedule built around atezolizumab (Tecentriq), an anti-PD-L1 antibody given alone or with chemotherapy, approved in the US since 2016.