1,527 articles
KBG syndrome
KBG syndrome (OMIM #148050) is a rare autosomal dominant neurodevelopmental disorder caused by ANKRD11 variants or 16q24.3 deletions, marked by macrodontia of upper central incisors, distinctive facial features, short stature, and developmental delay.
KCNQ2-related developmental and epileptic encephalopathy
KCNQ2-related developmental and epileptic encephalopathy (KCNQ2-DEE) is a rare neonatal epilepsy syndrome caused by KCNQ2 gene variants, with seizures starting in the first week of life.
Kernicterus
Kernicterus, also called bilirubin encephalopathy and kernicterus spectrum disorder, is irreversible neonatal brain damage from unconjugated bilirubin crossing the blood-brain barrier, causing athetoid cerebral palsy and hearing loss; preventable with phototherapy and exchange transfusion.
Kimberly Dawn Anderson-Erisman
Kimberly Dawn Anderson-Erisman is an American spinal cord injury rehabilitation researcher at MetroHealth and Case Western Reserve, elected to the National Academy of Medicine in 2023.
Kindling (neuroscience)
Kindling is an animal model of temporal lobe epilepsy in which repeated daily electrical stimulation of the amygdala or hippocampus progressively intensifies seizures until generalized convulsions occur, producing lasting seizure susceptibility.
Kjellin syndrome
Kjellin syndrome, also called SPG15 or spastic paraplegia-retinal degeneration syndrome, is a rare autosomal recessive HSP with retinal degeneration, thin corpus callosum, intellectual disability, and amyotrophy; more often caused by SPG11 than ZFYVE26 mutations.
Kleefstra syndrome
Kleefstra syndrome (KLEFS1, 9q34.3 microdeletion syndrome) is a rare autosomal-dominant neurodevelopmental disorder caused by EHMT1 haploinsufficiency, with intellectual disability, severe speech delay, hypotonia, heart and renal defects, and a distinctive face.
Kleine–Levin syndrome
Kleine–Levin syndrome, also called Sleeping beauty syndrome, is a rare neuropsychiatric sleep disorder with recurring bouts of severe sleepiness, cognitive impairment, and altered behavior, usually beginning in adolescence.
Knobloch syndrome
Knobloch syndrome (Knobloch-Layer syndrome, OMIM 267750) is a rare autosomal recessive disorder with high myopia, vitreoretinal degeneration, retinal detachment, and occipital encephalocele, caused mainly by COL18A1 mutations.
Kufor-Rakeb syndrome
Kufor-Rakeb syndrome (PARK9, MxMD-ATP13A2) is an ultra-rare autosomal recessive juvenile-onset atypical parkinsonism caused by ATP13A2 lysosomal ATPase mutations, with supranuclear gaze palsy, spasticity, dementia, and partial levodopa response.
L-2-hydroxyglutaric aciduria
L-2-hydroxyglutaric aciduria (L-2-HGA, OMIM 236792) is a rare autosomal recessive neurometabolic disorder caused by L2HGDH deficiency, causing L-2-hydroxyglutarate accumulation, progressive cerebellar ataxia, epilepsy, macrocephaly, and increased brain tumor risk.
L1 syndrome
L1 syndrome (CRASH syndrome, L1CAM syndrome): X-linked recessive neurodevelopmental disorder from L1CAM mutations, causing hydrocephalus, intellectual disability, leg spasticity, and adducted thumbs; HSAS form affects about 1 in 30,000 males.
Labyrinthine dysfunction
Labyrinthine dysfunction (ICD-11 AB36) is impaired function of the inner ear's bony or membranous labyrinth, causing vertigo, nystagmus, dysequilibrium, or hearing loss; causes include labyrinthitis, Ménière's disease, and labyrinthine ischemia via the AICA.
Labyrinthine fistula
Labyrinthine fistula (perilymphatic fistula, ICD-11 AB35, ICD-10 H83.1): an abnormal communication between the inner ear's perilymphatic space and the middle ear, usually at the oval or round window, most often caused by cholesteatoma erosion or trauma.
Lack of coordination
Lack of coordination, also called ataxia, is the inability to coordinate voluntary movements, producing jerky, unsteady motion and an unsteady gait; prolonged excessive alcohol use is the leading cause.
Lafora disease
Lafora disease, also called progressive myoclonus epilepsy type 2 (EPM2), is a fatal autosomal recessive epilepsy from EPM2A or NHLRC1 mutations causing insoluble Lafora bodies; onset at 8–19 years, median survival 11 years.
Lamb-Shaffer syndrome
Lamb-Shaffer syndrome (LAMSHF, SOX5 haploinsufficiency syndrome), a rare autosomal dominant neurodevelopmental disorder from SOX5 loss on 12p12.1, causing developmental delay, speech delay, intellectual disability, dysmorphism; first described 2012.
Lambert–Eaton myasthenic syndrome
Lambert–Eaton myasthenic syndrome (LEMS), also called Eaton-Lambert syndrome, is a rare autoimmune presynaptic neuromuscular junction disorder caused by P/Q-type VGCC antibodies, paraneoplastic in 50-60% of cases with small-cell lung cancer, treated with amifampridine, IVIg, and tumor therapy.
Landau-Kleffner syndrome
Landau-Kleffner syndrome (acquired epileptic aphasia, LKS): rare childhood epileptic encephalopathy with acquired auditory verbal agnosia, sleep-activated spike-wave EEG, seizures in about 70-75%, first described 1957.
Laryngeal abductor paralysis-intellectual disability syndrome
Laryngeal abductor paralysis-intellectual disability syndrome (Plott syndrome, ORPHA:2375, OMIM 308850) is a rare X-linked recessive disorder of males with congenital permanent vocal cord paralysis, severe neonatal stridor, and intellectual disability; gene not localized.
Late effects of cerebrovascular disease
Late effects of cerebrovascular disease (ICD-11 8B25; ICD-10 I69) are persisting residual symptoms after stroke or intracranial hemorrhage, including spasticity, depression, cognitive impairment, dementia, and recurrent stroke risk.
Late-onset retinal degeneration
Late-onset retinal degeneration (L-ORD, LORD) is a rare autosomal dominant retinal dystrophy caused by C1QTNF5 variants, especially the Scottish S163R founder mutation, causing midlife night blindness, sub-RPE deposits, and vision loss after age 50.
Lateral meningocele syndrome
Lateral meningocele syndrome, also called Lehman syndrome (LMS, OMIM 130720), is a rare autosomal dominant disorder caused by truncating NOTCH3 exon 33 variants, causing multiple lateral spinal meningoceles, distinctive facial features, and skeletal anomalies with usually normal cognition.
Laurence-Moon syndrome
Laurence-Moon syndrome (LMS, OMIM 245800, ORPHA 2377) is a very rare autosomal recessive PNPLA6-related disorder with progressive spastic paraplegia, chorioretinal dystrophy, and hypogonadism, distinct from Bardet-Biedl syndrome.
Lead poisoning
Lead poisoning, also called lead toxicity, is the toxic condition caused by absorption of lead into blood and tissues, particularly harmful to young children and women of child-bearing age.
Learning disability
Learning disability, clinically called specific learning disorder (DSM-5) or Developmental Learning Disorder (ICD-11), is a neurodevelopmental disorder causing persistent reading, writing, or math impairment despite adequate intelligence and instruction, affecting an estimated 5 to 15% of school-age children.
Leber congenital amaurosis
Leber congenital amaurosis (LCA, amaurosis congenita of Leber) is a group of inherited retinal dystrophies causing severe vision loss or blindness in the first year of life, usually autosomal recessive, involving over 20 genes including CEP290, GUCY2D, CRB1, and RPE65; RPE65-related disease is treatable with Luxturna gene therapy.
Leber hereditary optic neuropathy
Leber hereditary optic neuropathy, or Leber optic atrophy, is an inherited mitochondrial disease causing sudden, painless loss of central vision, typically in young adulthood, mainly in men.
Leber plus disease
Leber plus disease, also called LHON plus disease, is a rare inherited mitochondrial disease in which Leber hereditary optic neuropathy occurs alongside neurological or systemic abnormalities.
Lennox–Gastaut syndrome
Lennox–Gastaut syndrome (LGS) is a severe childhood-onset epilepsy with multiple drug-resistant seizure types, slow spike-and-wave EEG, intellectual disability, and treatments including valproate, lamotrigine, rufinamide, cannabidiol, callosotomy, and vagus nerve stimulation.