Human health and medicine

Focal dermal hypoplasia

Focal dermal hypoplasia (Goltz syndrome, Goltz-Gorlin syndrome) is a rare X-linked dominant PORCN-related multisystem disorder affecting skin, limbs, eyes, and face, seen almost exclusively in females, with about 300 reported cases.

Oct 20, 2026

Focal facial dermal dysplasia

Focal facial dermal dysplasia (FFDD), also called Brauer or Setleis syndrome types, is a rare genetic ectodermal dysplasia with congenital bitemporal or preauricular scar-like facial lesions, four subtypes, TWIST2 and CYP26C1 genes known.

Oct 20, 2026

Focal myoclonus

Focal myoclonus (ICD-11 8A06.2) is sudden involuntary jerking of a muscle or muscle group in a localized body area, of cortical, subcortical, spinal, or peripheral origin, diagnosed by EEG-EMG neurophysiology.

Focal myositis

Focal myositis (focal nodular myositis, inflammatory pseudotumor of skeletal muscle) is a rare, benign, localized inflammation of a single skeletal muscle, usually in the lower limb, presenting as a mass that typically regresses spontaneously; biopsy confirms diagnosis.

Focal segmental glomerulosclerosis

Focal segmental glomerulosclerosis (FSGS), also called segmental glomerulosclerosis or focal sclerosis with hyalinosis, is a podocyte-injury kidney disease causing scarring in parts of some glomeruli; it causes about 20% of childhood and 40% of adult nephrotic syndrome and is classified as primary, genetic, or secondary.

Focal seizure

Focal seizure (focal onset seizure): an epileptic seizure starting in networks limited to one brain hemisphere. Under the ILAE 2025 classification, types are focal preserved consciousness, focal impaired consciousness, and focal-to-bilateral tonic-clonic; consciousness replaces awareness as classifier; affects over 60% of people with epilepsy.

Focetria

Focetria, also called influenza vaccine H1N1v, was a Novartis (later Seqirus) MF59-adjuvanted pandemic H1N1 2009 vaccine from Siena, Italy; EU-authorized 2010, expired 2015, no narcolepsy signal.

Focus reduction neutralization assay

The focus reduction neutralization assay (FRNT), or focus reduction neutralization test, is a serological assay measuring neutralizing antibodies against viruses such as dengue and SARS-CoV-2.

Focused assessment with sonography for trauma

Focused assessment with sonography for trauma (FAST), also called eFAST in extended form, is a rapid bedside ultrasound protocol detecting free fluid, typically blood, in injured patients.

Focused ultrasound

Focused ultrasound, also known as focused ultrasound surgery, directs intersecting ultrasound beams through intact skin to ablate tissue, open the blood–brain barrier, or modulate neural activity.

Focusing (psychotherapy)

Focusing (psychotherapy): experiential method by Eugene Gendlin, from 1950s research with Carl Rogers at University of Chicago; attends to the bodily felt sense via six steps from his 1978 book, basis of Focusing-Oriented Therapy.

FODEPOC study

FODEPOC (NCT05853081) is a Spanish observational cohort study at Hospital General Universitario Gregorio Marañón testing whether the FODE scale, replacing BMI with fat-free mass index in the BODE index, better predicts COPD exacerbations and mortality.

FODMAP

FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides, polyols) are poorly absorbed short-chain carbohydrates; the Monash-developed low FODMAP diet treats IBS via elimination, reintroduction, and personalization phases, with RR 0.69 for global symptoms.

Oct 20, 2026

Foix-Chavany-Marie syndrome

Foix-Chavany-Marie syndrome (FCMS), or bilateral anterior opercular syndrome, is a rare pseudobulbar palsy with anarthria, facio-pharyngo-glosso-masticatory paralysis, and preserved automatic movements, usually from bilateral opercular strokes.

Folate

Folate (vitamin B9) is a water-soluble B vitamin, also called folacin, needed for DNA synthesis and one-carbon metabolism. Folic acid is its synthetic form; 400 mcg daily periconceptionally prevents neural tube defects.

Folate deficiency

Folate deficiency (folic acid, vitamin B9 deficiency): low blood folate causing megaloblastic anemia; causes include poor diet, alcohol, malabsorption, and drugs; preventable with 400 µg daily and grain fortification.

Foley catheter

Foley catheter, indwelling urinary catheter with an inflatable balloon tip, introduced by Frederic Foley in 1935; two-channel design for bladder drainage, used in 15-25% of hospitalized patients, main risks CAUTI and noninfectious complications.

FOLFIRI

FOLFIRI is a cyclic intravenous chemotherapy regimen combining irinotecan, fluorouracil, and leucovorin, repeated every 14 days, used mainly as first-line treatment for metastatic colorectal cancer.

FOLFIRINOX

FOLFIRINOX is a four-drug chemotherapy regimen combining folinic acid, fluorouracil, irinotecan, and oxaliplatin, used first-line for metastatic pancreatic cancer, where it outperformed gemcitabine, and in modified form after resection.

FOLFOX

FOLFOX (Oxaliplatin de Gramont, OxMdG) is a combination chemotherapy regimen of leucovorin, fluorouracil, and oxaliplatin used to treat colorectal cancer, established as adjuvant standard for stage III colon cancer by the MOSAIC trial.

FOLFOX chemotherapy

FOLFOX, also known as Oxaliplatin de Gramont or OxMdG, is a combination chemotherapy regimen of folinic acid, fluorouracil, and oxaliplatin, used mainly to treat colorectal cancer.

FOLFOXIRI

FOLFOXIRI is a combination chemotherapy regimen pairing infusional fluorouracil with leucovorin, oxaliplatin, and irinotecan in two-weekly cycles, used mainly as first-line treatment for metastatic colorectal cancer.

Folie à deux

Folie à deux, or shared psychotic disorder, is a rare condition in which delusions are transmitted from an inducer to a close associate. Also called induced delusional disorder; subtypes include folie imposée, communiquée, simultanée, and induite.

Folinic acid

Folinic acid (leucovorin calcium, citrovorum factor), 5-formyltetrahydrofolate, a reduced folate used for methotrexate rescue, 5-FU modulation in FOLFOX/FOLFIRI, and, since March 2026, the first approved treatment for FOLR1 cerebral folate transport deficiency, not autism.

Folinic acid-responsive seizures

Folinic acid-responsive seizures (FARS), also called folinic acid responsive developmental and epileptic encephalopathy, is a rare neonatal epileptic encephalopathy with myoclonic and clonic seizures with apnea, responding to folinic acid; genetically identical to pyridoxine-dependent epilepsy (ALDH7A1) or caused by FOLR1 folate transport defects.

Folitixorin

Folitixorin (5,10-methylenetetrahydrofolate; CoFactor, ANX-510) is a folate-based biomodulator, INN 8881, UNII 0SXY5ET48B, that stabilizes FdUMP binding to thymidylate synthase to potentiate 5-fluorouracil; its [6R] isomer arfolitixorin failed superiority over leucovorin in the phase III AGENT trial.

Follicle-stimulating hormone

Follicle-stimulating hormone (FSH, follitropin) is an anterior pituitary glycoprotein gonadotropin with common alpha and unique beta subunits; it drives ovarian follicle growth via granulosa-cell FSHR and Sertoli-cell support of spermatogenesis, and is used in fertility treatment.

Follicular carcinoma of thyroid gland

Follicular thyroid carcinoma (FTC), a malignant follicular-cell thyroid tumor, second most common thyroid cancer after papillary; diagnosis requires capsular or vascular invasion, treated with lobectomy or total thyroidectomy plus radioactive iodine.

Follicular conjunctivitis

Follicular conjunctivitis, ICD-11 9A60.1, is conjunctival inflammation with lymphoid follicles, usually viral (adenovirus) or chlamydial, sometimes toxic from eye drops; follicles distinguish it from papillary bacterial or allergic conjunctivitis.