Hereditary hyperekplexia is an ultra-rare Mendelian neuromotor disorder of inhibitory glycinergic neurotransmission. Affected neonates and infants have excessive startle responses with stiffness, hypertonia, myoclonus, and gait disturbance; some patients have recurrent apnea, developmental delay, speech delay, seizures, or gastrointestinal complications. Pathogenic variants in GLRA1, GLRB, and SLC6A5 are the best-established causes, with additional disease-causing genes including GPHN and ATAD1.
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name: Hereditary Hyperekplexia
creation_date: "2026-05-10T19:24:25Z"
updated_date: "2026-05-10T19:44:19Z"
description: >-
Hereditary hyperekplexia is an ultra-rare Mendelian neuromotor disorder of
inhibitory glycinergic neurotransmission. Affected neonates and infants have
excessive startle responses with stiffness, hypertonia, myoclonus, and gait
disturbance; some patients have recurrent apnea, developmental delay, speech
delay, seizures, or gastrointestinal complications. Pathogenic variants in
GLRA1, GLRB, and SLC6A5 are the best-established causes, with additional
disease-causing genes including GPHN and ATAD1.
category: Mendelian
parents:
- Hereditary Neurological Disease
- Movement Disorder
- Channelopathy
synonyms:
- Congenital stiff man syndrome
- Familial startle disease
- Hereditary hyperexplexia
- Kok disease
- Stiff baby syndrome
disease_term:
preferred_term: hereditary hyperekplexia
term:
id: MONDO:0021022
label: hereditary hyperekplexia
prevalence:
- population: Worldwide
percentage: <1 per 1,000,000
notes: Orphanet reports hereditary hyperekplexia as an ultra-rare disorder.
evidence:
- reference: ORPHA:3197
supports: SUPPORT
snippet: "<1 / 1 000 000 | Worldwide | Point prevalence | ORPHANET"
explanation: Orphanet provides a worldwide point-prevalence estimate below one per million.
inheritance:
- name: Autosomal dominant
inheritance_term:
preferred_term: Autosomal dominant inheritance
term:
id: HP:0000006
label: Autosomal dominant inheritance
evidence:
- reference: ORPHA:3197
supports: SUPPORT
snippet: "Autosomal dominant"
explanation: Orphanet lists autosomal dominant inheritance for hereditary hyperekplexia.
- name: Autosomal recessive
inheritance_term:
preferred_term: Autosomal recessive inheritance
term:
id: HP:0000007
label: Autosomal recessive inheritance
evidence:
- reference: ORPHA:3197
supports: SUPPORT
snippet: "Autosomal recessive"
explanation: Orphanet lists autosomal recessive inheritance for hereditary hyperekplexia.
progression:
- phase: Neonatal or infantile onset
age_range: Neonatal period to infancy
notes: >-
Symptoms typically begin in the neonatal period or infancy, and gene-positive
cohorts can have recurrent apnea and developmental delay.
evidence:
- reference: ORPHA:3197
supports: SUPPORT
snippet: "Age of onset: Neonatal"
explanation: Orphanet records neonatal onset.
- reference: ORPHA:3197
supports: SUPPORT
snippet: "Age of onset: Infancy"
explanation: Orphanet records infantile onset.
- reference: PMID:24030948
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "all gene-positive cases present in the neonatal period (occasionally prenatally)"
explanation: The 97-person genetically confirmed cohort supports neonatal presentation.
pathophysiology:
- name: Postsynaptic Glycine Receptor Chloride Channel Dysfunction
description: >-
GLRA1 and GLRB variants impair the postsynaptic inhibitory glycine receptor,
a ligand-gated chloride channel that normally mediates rapid inhibitory
signaling in the brainstem and spinal cord.
genes:
- preferred_term: GLRA1
term:
id: hgnc:4326
label: GLRA1
- preferred_term: GLRB
term:
id: hgnc:4329
label: GLRB
molecular_functions:
- preferred_term: extracellularly glycine-gated chloride channel activity
term:
id: GO:0016934
label: extracellularly glycine-gated chloride channel activity
biological_processes:
- preferred_term: chemical synaptic transmission
term:
id: GO:0007268
label: chemical synaptic transmission
cell_types:
- preferred_term: neuron
term:
id: CL:0000540
label: neuron
evidence:
- reference: PMID:8651283
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Dominant missense mutations in the human glycine receptor (GlyR) alpha 1 subunit gene (GLRA1) give rise to hereditary hyperekplexia."
explanation: This establishes GLRA1 glycine receptor variants as a cause of hereditary hyperekplexia.
- reference: PMID:8651283
supports: SUPPORT
evidence_source: IN_VITRO
snippet: "These mutations impair agonist affinities and change conductance states of expressed mutant channels, resulting in a partial loss of function."
explanation: Functional channel evidence supports reduced glycine receptor activity.
- reference: PMID:11929858
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Following mutation analysis of the human beta-subunit of hGlyR (GLRB) in a cohort of 22 hyperekplexia patients, we provide evidence to confirm that GLRB mutations can cause human hyperekplexia."
explanation: Human mutation analysis supports GLRB as a causal glycine receptor subunit gene.
downstream:
- target: Glycinergic Inhibitory Neurotransmission Failure
causal_link_type: DIRECT
description: Glycine receptor channel dysfunction reduces rapid inhibitory glycinergic signaling.
evidence:
- reference: PMID:11929858
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "These receptors facilitate fast-response, inhibitory glycinergic neurotransmission in the brainstem and spinal cord leading to a rapid modification and reduction of the excitatory startle response."
explanation: The cited abstract directly links glycine receptor activity to inhibitory signaling that suppresses startle.
- name: Presynaptic Glycine Transporter Dysfunction
description: >-
SLC6A5 encodes the presynaptic glycine transporter GlyT2. Pathogenic variants
reduce transporter localization or glycine uptake, limiting presynaptic
glycine recycling needed for inhibitory synaptic transmission.
genes:
- preferred_term: SLC6A5
term:
id: hgnc:11051
label: SLC6A5
molecular_functions:
- preferred_term: glycine transmembrane transporter activity
term:
id: GO:0015187
label: glycine transmembrane transporter activity
biological_processes:
- preferred_term: chemical synaptic transmission
term:
id: GO:0007268
label: chemical synaptic transmission
cell_types:
- preferred_term: neuron
term:
id: CL:0000540
label: neuron
evidence:
- reference: PMID:16751771
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Here we show that missense, nonsense and frameshift mutations in SLC6A5 (ref. 8), encoding the presynaptic glycine transporter 2 (GlyT2), also cause hyperekplexia."
explanation: This directly supports SLC6A5 as a presynaptic cause of hyperekplexia.
- reference: PMID:16751771
supports: SUPPORT
evidence_source: IN_VITRO
snippet: "SLC6A5 mutations result in defective subcellular GlyT2 localization, decreased glycine uptake or both, with selected mutations affecting predicted glycine and Na+ binding sites."
explanation: Functional data support impaired GlyT2 localization and glycine uptake as the mechanism.
- reference: PMID:22753417
supports: SUPPORT
evidence_source: IN_VITRO
snippet: "This interaction impairs transporter maturation through the secretory pathway, reduces surface expression, and inhibits transport function."
explanation: Functional GlyT2 evidence supports impaired trafficking and transport as a presynaptic mechanism.
downstream:
- target: Glycinergic Inhibitory Neurotransmission Failure
causal_link_type: DIRECT
description: Reduced GlyT2 function disrupts presynaptic glycine availability for inhibitory signaling.
evidence:
- reference: PMID:16751771
supports: SUPPORT
evidence_source: IN_VITRO
snippet: "SLC6A5 mutations result in defective subcellular GlyT2 localization, decreased glycine uptake or both, with selected mutations affecting predicted glycine and Na+ binding sites."
explanation: Reduced glycine uptake provides the presynaptic link to impaired glycinergic neurotransmission.
- name: Glycinergic Inhibitory Neurotransmission Failure
description: >-
Failure of glycinergic inhibition in brainstem and spinal startle circuits
leaves excitatory startle reflex pathways insufficiently suppressed,
producing excessive startle, stiffness, and related neuromotor features.
biological_processes:
- preferred_term: chemical synaptic transmission
term:
id: GO:0007268
label: chemical synaptic transmission
cell_types:
- preferred_term: neuron
term:
id: CL:0000540
label: neuron
evidence:
- reference: PMID:23184146
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Glycinergic neurotransmission is a major inhibitory influence in the CNS and its disruption triggers a paediatric and adult startle disorder, hyperekplexia."
explanation: The abstract directly links disrupted glycinergic neurotransmission to hyperekplexia.
- reference: PMID:8651283
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "The child displayed exaggerated startle responses and pronounced head-retraction jerks reflecting a disinhibition of vestigial brain-stem reflexes."
explanation: This supports brainstem-reflex disinhibition as the clinical circuit consequence.
phenotypes:
- category: Neurological
name: Exaggerated Startle Response
description: Excessive startle responses are the defining neurologic manifestation.
phenotype_term:
preferred_term: Exaggerated startle response
term:
id: HP:0002267
label: Exaggerated startle response
evidence:
- reference: ORPHA:3197
supports: SUPPORT
snippet: "Hereditary hyperekplexia is a hereditary neurological disorder characterized by excessive startle responses."
explanation: Orphanet defines hereditary hyperekplexia by excessive startle responses.
- reference: PMID:16751771
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Individuals with mutations in SLC6A5 present with hypertonia, an exaggerated startle response to tactile or acoustic stimuli, and life-threatening neonatal apnea episodes."
explanation: Human SLC6A5 cases directly support exaggerated tactile or acoustic startle.
- category: Neurological
name: Ataxia
frequency: VERY_FREQUENT
description: Ataxia is listed by Orphanet as a very frequent neurologic manifestation.
phenotype_term:
preferred_term: Ataxia
term:
id: HP:0001251
label: Ataxia
evidence:
- reference: ORPHA:3197
supports: SUPPORT
snippet: "HP:0001251 | Ataxia | Very frequent (99-80%)"
explanation: Orphanet lists ataxia as very frequent in hereditary hyperekplexia.
- category: Neurological
name: Spasticity
frequency: VERY_FREQUENT
description: Spasticity is a very frequent motor feature.
phenotype_term:
preferred_term: Spasticity
term:
id: HP:0001257
label: Spasticity
evidence:
- reference: ORPHA:3197
supports: SUPPORT
snippet: "HP:0001257 | Spasticity | Very frequent (99-80%)"
explanation: Orphanet lists spasticity as very frequent.
- category: Neurological
name: Hypertonia
frequency: VERY_FREQUENT
description: Hypertonia is part of the stiff-neonate presentation.
phenotype_term:
preferred_term: Hypertonia
term:
id: HP:0001276
label: Hypertonia
evidence:
- reference: ORPHA:3197
supports: SUPPORT
snippet: "HP:0001276 | Hypertonia | Very frequent (99-80%)"
explanation: Orphanet lists hypertonia as very frequent.
- reference: PMID:16751771
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Individuals with mutations in SLC6A5 present with hypertonia, an exaggerated startle response to tactile or acoustic stimuli, and life-threatening neonatal apnea episodes."
explanation: Human SLC6A5 cases directly support hypertonia.
- category: Neurological
name: Gait Disturbance
frequency: FREQUENT
description: Startle-related stiffness and stumbles can produce gait disturbance.
phenotype_term:
preferred_term: Gait disturbance
term:
id: HP:0001288
label: Gait disturbance
evidence:
- reference: ORPHA:3197
supports: SUPPORT
snippet: "HP:0001288 | Gait disturbance | Frequent (79-30%)"
explanation: Orphanet lists gait disturbance as frequent.
- category: Neurological
name: Myoclonus
frequency: VERY_FREQUENT
description: Myoclonus is a very frequent movement manifestation.
phenotype_term:
preferred_term: Myoclonus
term:
id: HP:0001336
label: Myoclonus
evidence:
- reference: ORPHA:3197
supports: SUPPORT
snippet: "HP:0001336 | Myoclonus | Very frequent (99-80%)"
explanation: Orphanet lists myoclonus as very frequent.
- category: Neurological
name: Hyperreflexia
frequency: VERY_FREQUENT
description: Hyperreflexia is a very frequent neurologic finding.
phenotype_term:
preferred_term: Hyperreflexia
term:
id: HP:0001347
label: Hyperreflexia
evidence:
- reference: ORPHA:3197
supports: SUPPORT
snippet: "HP:0001347 | Hyperreflexia | Very frequent (99-80%)"
explanation: Orphanet lists hyperreflexia as very frequent.
- category: Musculoskeletal
name: Joint Dislocation
frequency: OCCASIONAL
description: Joint dislocation is an occasional complication, likely related to severe stiffness or startle.
phenotype_term:
preferred_term: Joint dislocation
term:
id: HP:0001373
label: Joint dislocation
evidence:
- reference: ORPHA:3197
supports: SUPPORT
snippet: "HP:0001373 | Joint dislocation | Occasional (29-5%)"
explanation: Orphanet lists joint dislocation as occasional.
- category: Musculoskeletal
name: Joint Stiffness
frequency: VERY_FREQUENT
description: Joint stiffness accompanies the generalized stiff phenotype.
phenotype_term:
preferred_term: Joint stiffness
term:
id: HP:0001387
label: Joint stiffness
evidence:
- reference: ORPHA:3197
supports: SUPPORT
snippet: "HP:0001387 | Joint stiffness | Very frequent (99-80%)"
explanation: Orphanet lists joint stiffness as very frequent.
- category: Gastrointestinal
name: Umbilical Hernia
frequency: FREQUENT
description: Umbilical hernia is a frequent associated manifestation.
phenotype_term:
preferred_term: Umbilical hernia
term:
id: HP:0001537
label: Umbilical hernia
evidence:
- reference: ORPHA:3197
supports: SUPPORT
snippet: "HP:0001537 | Umbilical hernia | Frequent (79-30%)"
explanation: Orphanet lists umbilical hernia as frequent.
- category: Gastrointestinal
name: Gastroesophageal Reflux
frequency: VERY_FREQUENT
description: Gastroesophageal reflux is a very frequent gastrointestinal manifestation.
phenotype_term:
preferred_term: Gastroesophageal reflux
term:
id: HP:0002020
label: Gastroesophageal reflux
evidence:
- reference: ORPHA:3197
supports: SUPPORT
snippet: "HP:0002020 | Gastroesophageal reflux | Very frequent (99-80%)"
explanation: Orphanet lists gastroesophageal reflux as very frequent.
- category: Gastrointestinal
name: Hiatus Hernia
frequency: VERY_FREQUENT
description: Hiatus hernia is a very frequent gastrointestinal-associated feature.
phenotype_term:
preferred_term: Hiatus hernia
term:
id: HP:0002036
label: Hiatus hernia
evidence:
- reference: ORPHA:3197
supports: SUPPORT
snippet: "HP:0002036 | Hiatus hernia | Very frequent (99-80%)"
explanation: Orphanet lists hiatus hernia as very frequent.
- category: Neurological
name: Rigidity
frequency: VERY_FREQUENT
description: Rigidity contributes to the stiff-baby presentation.
phenotype_term:
preferred_term: Rigidity
term:
id: HP:0002063
label: Rigidity
evidence:
- reference: ORPHA:3197
supports: SUPPORT
snippet: "HP:0002063 | Rigidity | Very frequent (99-80%)"
explanation: Orphanet lists rigidity as very frequent.
- category: Sleep
name: Sleep Abnormality
frequency: FREQUENT
description: Sleep abnormalities are frequent in Orphanet's phenotype table.
phenotype_term:
preferred_term: Sleep abnormality
term:
id: HP:0002360
label: Sleep disturbance
evidence:
- reference: ORPHA:3197
supports: SUPPORT
snippet: "HP:0002360 | Sleep abnormality | Frequent (79-30%)"
explanation: Orphanet lists sleep abnormality as frequent.
- category: Neurological
name: Fasciculations
frequency: VERY_FREQUENT
description: Fasciculations are listed as a very frequent neuromotor manifestation.
phenotype_term:
preferred_term: Fasciculations
term:
id: HP:0002380
label: Fasciculations
evidence:
- reference: ORPHA:3197
supports: SUPPORT
snippet: "HP:0002380 | Fasciculations | Very frequent (99-80%)"
explanation: Orphanet lists fasciculations as very frequent.
- category: Musculoskeletal
name: Hip Dislocation
frequency: OCCASIONAL
description: Hip dislocation is an occasional musculoskeletal complication.
phenotype_term:
preferred_term: Hip dislocation
term:
id: HP:0002827
label: Hip dislocation
evidence:
- reference: ORPHA:3197
supports: SUPPORT
snippet: "HP:0002827 | Hip dislocation | Occasional (29-5%)"
explanation: Orphanet lists hip dislocation as occasional.
- category: Neurological
name: Muscle Stiffness
frequency: VERY_FREQUENT
description: Muscle stiffness is a core component of the classic stiffness-startles-stumbles triad.
phenotype_term:
preferred_term: Muscle stiffness
term:
id: HP:0003552
label: Muscle stiffness
evidence:
- reference: ORPHA:3197
supports: SUPPORT
snippet: "HP:0003552 | Muscle stiffness | Very frequent (99-80%)"
explanation: Orphanet lists muscle stiffness as very frequent.
- reference: PMID:24030948
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "In addition to the characteristic 'stiffness, startles and stumbles' of hyperekplexia"
explanation: The genetically confirmed cohort identifies stiffness as a characteristic feature.
- category: Neurological
name: Abnormality of Movement
frequency: VERY_FREQUENT
description: Abnormal movement is a broad very frequent Orphanet phenotype category.
phenotype_term:
preferred_term: Abnormality of movement
term:
id: HP:0100022
label: Abnormality of movement
evidence:
- reference: ORPHA:3197
supports: SUPPORT
snippet: "HP:0100022 | Abnormality of movement | Very frequent (99-80%)"
explanation: Orphanet lists abnormality of movement as very frequent.
- category: Gastrointestinal
name: Esophagitis
frequency: VERY_FREQUENT
description: Esophagitis is a very frequent gastrointestinal manifestation.
phenotype_term:
preferred_term: Esophagitis
term:
id: HP:0100633
label: Esophagitis
evidence:
- reference: ORPHA:3197
supports: SUPPORT
snippet: "HP:0100633 | Esophagitis | Very frequent (99-80%)"
explanation: Orphanet lists esophagitis as very frequent.
- category: Gastrointestinal
name: Hernia
frequency: FREQUENT
description: Hernia is a frequent associated finding in Orphanet.
phenotype_term:
preferred_term: Hernia
term:
id: HP:0100790
label: Hernia
evidence:
- reference: ORPHA:3197
supports: SUPPORT
snippet: "HP:0100790 | Hernia | Frequent (79-30%)"
explanation: Orphanet lists hernia as frequent.
- category: Respiratory
name: Neonatal Apnea Episodes
frequency: FREQUENT
description: Recurrent apnea attacks are common, especially in SLC6A5-associated disease.
phenotype_term:
preferred_term: Apnea
term:
id: HP:0002104
label: Apnea
onset:
onset_category: NEONATAL
evidence:
- reference: PMID:24030948
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "apnoea attacks (50 of 89) and delayed development (47 of 92) were frequently reported."
explanation: The cohort reports apnea attacks in 50 of 89 individuals, supporting a frequent band.
- reference: PMID:16751771
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Individuals with mutations in SLC6A5 present with hypertonia, an exaggerated startle response to tactile or acoustic stimuli, and life-threatening neonatal apnea episodes."
explanation: SLC6A5 cases directly support neonatal apnea episodes.
- category: Neurodevelopmental
name: Developmental Delay
frequency: FREQUENT
description: Developmental delay is frequent in gene-positive cohorts and enriched in GLRB and SLC6A5 cases.
phenotype_term:
preferred_term: Global developmental delay
term:
id: HP:0001263
label: Global developmental delay
evidence:
- reference: PMID:24030948
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "apnoea attacks (50 of 89) and delayed development (47 of 92) were frequently reported."
explanation: The cohort reports delayed development in 47 of 92 individuals, supporting a frequent band.
- reference: PMID:24030948
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Patients with GLRB and SLC6A5 mutations were more likely to have developmental delay"
explanation: Genotype-phenotype data support developmental delay particularly in GLRB and SLC6A5 disease.
- reference: PMID:22753417
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "In addition to classical hyperekplexia symptoms, some individuals had abnormal respiration, facial dysmorphism, delayed motor development, or intellectual disability."
explanation: The dominant GlyT2 family report supports delayed motor development among SLC6A5-associated presentations.
- category: Neurodevelopmental
name: Speech and Language Delay
frequency: OCCASIONAL
description: >-
Delayed speech acquisition is a genotype-enriched neurodevelopmental feature,
particularly in GLRB-associated hyperekplexia.
phenotype_term:
preferred_term: Delayed speech and language development
term:
id: HP:0000750
label: Delayed speech and language development
evidence:
- reference: PMID:24030948
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "61 cases had mutations in GLRA1, 24 cases in SLC6A5 and 12 in GLRB."
explanation: The cohort denominator supports interpreting GLRB-specific speech delay as a minority overall phenotype.
- reference: PMID:24030948
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "92% of GLRB cases reported a mild to severe delay in speech acquisition."
explanation: Genotype-phenotype data directly support delayed speech acquisition in GLRB-associated hyperekplexia.
- category: Neurological
name: Seizure
frequency: OCCASIONAL
description: Seizures are an occasional neurologic manifestation.
phenotype_term:
preferred_term: Seizure
term:
id: HP:0001250
label: Seizure
evidence:
- reference: ORPHA:3197
supports: SUPPORT
snippet: "HP:0001250 | Seizure | Occasional (29-5%)"
explanation: Orphanet lists seizure as occasional.
- category: Neurodevelopmental
name: Intellectual Disability
frequency: OCCASIONAL
description: Intellectual disability is an occasional associated neurodevelopmental feature.
phenotype_term:
preferred_term: Intellectual disability
term:
id: HP:0001249
label: Intellectual disability
evidence:
- reference: ORPHA:3197
supports: SUPPORT
snippet: "HP:0001249 | Intellectual disability | Occasional (29-5%)"
explanation: Orphanet lists intellectual disability as occasional.
genetic:
- name: GLRA1 Pathogenic Variants
association: Pathogenic Variants
gene_term:
preferred_term: GLRA1
term:
id: hgnc:4326
label: GLRA1
inheritance:
- name: Autosomal dominant
inheritance_term:
preferred_term: Autosomal dominant inheritance
term:
id: HP:0000006
label: Autosomal dominant inheritance
- name: Autosomal recessive
inheritance_term:
preferred_term: Autosomal recessive inheritance
term:
id: HP:0000007
label: Autosomal recessive inheritance
features: >-
GLRA1 encodes the alpha 1 subunit of the inhibitory glycine receptor.
Dominant missense variants and recessive loss-of-function alleles have been
reported in hereditary hyperekplexia.
evidence:
- reference: ORPHA:3197
supports: SUPPORT
snippet: "GLRA1 | glycine receptor alpha 1 | hgnc:4326 | Disease-causing germline mutation(s) in"
explanation: Orphanet lists GLRA1 as a disease-causing gene for hereditary hyperekplexia.
- reference: PMID:8651283
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Dominant missense mutations in the human glycine receptor (GlyR) alpha 1 subunit gene (GLRA1) give rise to hereditary hyperekplexia."
explanation: Human genetic evidence supports dominant GLRA1-associated disease.
- reference: PMID:8651283
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "In a recessive case of hyperekplexia, we found a deletion of exons 1-6 of the GLRA1 gene."
explanation: This supports recessive GLRA1-associated hyperekplexia.
- name: GLRB Pathogenic Variants
association: Pathogenic Variants
gene_term:
preferred_term: GLRB
term:
id: hgnc:4329
label: GLRB
inheritance:
- name: Autosomal dominant
inheritance_term:
preferred_term: Autosomal dominant inheritance
term:
id: HP:0000006
label: Autosomal dominant inheritance
- name: Autosomal recessive
inheritance_term:
preferred_term: Autosomal recessive inheritance
term:
id: HP:0000007
label: Autosomal recessive inheritance
features: >-
GLRB encodes the beta subunit of the inhibitory glycine receptor. Both
recessive and dominant GLRB variants are reported in hyperekplexia, with
long-term additive outcomes including apnea and developmental delay.
evidence:
- reference: ORPHA:3197
supports: SUPPORT
snippet: "GLRB | glycine receptor beta | hgnc:4329 | Disease-causing germline mutation(s) in"
explanation: Orphanet lists GLRB as a disease-causing gene for hereditary hyperekplexia.
- reference: PMID:23184146
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "The screening identified recessive and dominant GLRB variants in 12 unrelated hyperekplexia probands."
explanation: Human cohort data support both recessive and dominant GLRB-associated disease.
- name: SLC6A5 Pathogenic Variants
association: Pathogenic Variants
gene_term:
preferred_term: SLC6A5
term:
id: hgnc:11051
label: SLC6A5
inheritance:
- name: Autosomal recessive
inheritance_term:
preferred_term: Autosomal recessive inheritance
term:
id: HP:0000007
label: Autosomal recessive inheritance
- name: Autosomal dominant
inheritance_term:
preferred_term: Autosomal dominant inheritance
term:
id: HP:0000006
label: Autosomal dominant inheritance
features: >-
SLC6A5 encodes GlyT2, the presynaptic glycine transporter. Pathogenic
variants reduce transporter function and are associated with recessive and
rare dominant disease with a challenging phenotype that can include
recurrent neonatal apnea and developmental delay.
evidence:
- reference: ORPHA:3197
supports: SUPPORT
snippet: "SLC6A5 | solute carrier family 6 member 5 | hgnc:11051 | Disease-causing germline mutation(s) in"
explanation: Orphanet lists SLC6A5 as a disease-causing gene for hereditary hyperekplexia.
- reference: PMID:16751771
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Here we show that missense, nonsense and frameshift mutations in SLC6A5 (ref. 8), encoding the presynaptic glycine transporter 2 (GlyT2), also cause hyperekplexia."
explanation: Human genetic evidence supports SLC6A5 as a presynaptic disease gene.
- reference: PMID:22753417
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "In this study, systematic DNA sequencing of SLC6A5 revealed a new dominant GlyT2 mutation"
explanation: This family study supports rare dominant SLC6A5-associated hyperekplexia.
- name: GPHN Pathogenic Variants
association: Pathogenic Variants
gene_term:
preferred_term: GPHN
term:
id: hgnc:15465
label: GPHN
features: >-
GPHN encodes gephyrin, a postsynaptic scaffolding protein for inhibitory
receptors. Orphanet lists GPHN as a disease-causing gene for hereditary
hyperekplexia.
evidence:
- reference: ORPHA:3197
supports: SUPPORT
snippet: "GPHN | gephyrin | hgnc:15465 | Disease-causing germline mutation(s) in"
explanation: Orphanet lists GPHN as a disease-causing gene for hereditary hyperekplexia.
- name: ATAD1 Pathogenic Variants
association: Pathogenic Variants
gene_term:
preferred_term: ATAD1
term:
id: hgnc:25903
label: ATAD1
features: >-
ATAD1 is included by Orphanet among disease-causing genes for hereditary
hyperekplexia; its contribution is represented here as a gene association
pending additional curated mechanism evidence.
evidence:
- reference: ORPHA:3197
supports: SUPPORT
snippet: "ATAD1 | ATPase family AAA domain containing 1 | hgnc:25903 | Disease-causing germline mutation(s) in"
explanation: Orphanet lists ATAD1 as a disease-causing gene for hereditary hyperekplexia.
diagnosis:
- name: Molecular Genetic Testing
description: >-
Molecular genetic testing confirms the diagnosis in symptomatic neonates and
supports counseling for families at risk, especially where GLRB or SLC6A5
variants are suspected.
diagnosis_term:
preferred_term: molecular genetic testing
term:
id: MAXO:0000533
label: molecular genetic testing
evidence:
- reference: PMID:24030948
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Ninety-seven individuals had a clinical diagnosis of hyperekplexia confirmed by genetic testing"
explanation: The cohort used genetic testing to confirm clinical hyperekplexia diagnoses.
- reference: PMID:24030948
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "We recommend early genetic testing for symptomatic neonates and possibly preconception counselling for those at risk for GLRB and SLC6A5 mutations"
explanation: The authors recommend early genetic testing for symptomatic neonates.
treatments:
- name: Clonazepam
description: >-
Clonazepam is the standard symptomatic pharmacotherapy for hyperekplexia,
reducing excessive startle and stiffness in most treated genetically
confirmed patients.
treatment_term:
preferred_term: Pharmacotherapy
term:
id: NCIT:C15986
label: Pharmacotherapy
therapeutic_agent:
- preferred_term: clonazepam
term:
id: CHEBI:3756
label: clonazepam
target_mechanisms:
- target: Glycinergic Inhibitory Neurotransmission Failure
treatment_effect: MODULATES
description: Clonazepam increases inhibitory tone symptomatically rather than correcting the causal gene defect.
evidence:
- reference: PMID:24030948
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "clonazepam is the treatment of choice (95% found it to be efficacious)."
explanation: The genetically confirmed cohort reports clonazepam efficacy in nearly all treated patients.
This report is retrieval-only and is generated directly from Asta results.
search_papers_by_relevance with snippet_search.