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A complex neurodevelopmental disorder characterized by a range of developmental delays and epileptic encephalopathy phenotypes. Seizure onset is variable and intellectual disability is variable in presence and severity.
No HPO annotations are available for this condition.
Age of onset: childhood, before birth, newborn period, at birth, infancy, adolescence.
To date, 83 individuals have been identified with a pathogenic variant in HNRNPU [, , , , , , , , , , , ]. The following description of the phenotypic features associated with this condition is based on these reports. Table 2. Select Features of HNRNPU-Related Neurodevelopmental Disorder
No consensus clinical diagnostic criteria for HNRNPU-related neurodevelopmental disorder (HNRNPU-NDD) have been published.
HNRNPU-NDD should be considered in individuals with the following clinical and brain MRI findings. Clinical findings (presenting in infancy or childhood). Moderate-to-severe developmental delay (DD) or intellectual disability (ID) AND any of the following:
Generalized hypotonia of infancy
No approved treatments are currently available for genetic developmental and epileptic encephalopathy. The disease remains an area of unmet medical need.
No clinical practice guidelines for HNRNPU-related neurodevelopmental disorder (HNRNPU-NDD) have been published. Evaluations Following Initial Diagnosis To establish the extent of disease and needs in an individual diagnosed with HNRNPU-NDD, the evaluations summarized (if not performed as part of the evaluation that led to diagnosis) are recommended. Table 3. Recommended Evaluations Following Initial Diagnosis in Individuals with HNRNPU-Related Neurodevelopmental Disorder
Table 5.
Recommended Surveillance for Individuals with HNRNPU-Related Neurodevelopmental Disorder
System/Concern | Evaluation | Frequency
| • Measurement of growth parameters
Eval of nutritional status safety of oral intake
No clinical trials have been registered for genetic developmental and epileptic encephalopathy.
281 publications have been identified in PubMed for genetic developmental and epileptic encephalopathy. Research spans Review / Meta-Analysis (33%), Basic Science / Preclinical (22%), and Epidemiology / Natural History (15%).
Research Type | Count | % of Total |
|---|---|---|
Research summaries | 74 | 33% |
Data assembled from 3 of 12 sources · Last updated Nov 3, 2026, 11:19 AM UTC
Genetic and Rare Diseases Info Center
Feature | % of Personsw/Feature | Comment |
|---|---|---|
Developmental delay | 100% | — |
Dysmorphic craniofacial features | 97% | See Dysmorphic features following this table. |
Seizure disorder | 95% | ~90% have 1st seizure before age 24 mos (tonic-clonic in ~60%, absence in ~44%)1 |
Intellectual disability | 84% | Typically moderate to severe |
Speech delay | 80% | Usually limited or no speech |
Hypotonia | 79% | Slightly fewer than 50% have congenital hypotonia. |
Feeding difficulties | 57% | Some require supplemental nasogastric feeding or percutaneous gastrostomy. |
Behavioral issues | 50% | Autistic features are observed in ~33% of affected persons. |
Eye anomalies | 36% | The most common finding is strabismus. |
Cardiac abnormalities | 30% | Septal defects are the most common. |
Renal anomalies | 10% | — |
Hyperventilation apnea | Rare | 1. Developmental delay (DD) and intellectual disability (ID), typically affecting all developmental domains and falling into the moderate-to-severe range, have been found in all reported individuals to date. |
Source: GeneReviews — "HNRNPU-Related Neurodevelopmental Disorder"
Infant feeding difficulties
Speech and language delay and/ or absent speech
Autism spectrum disorder or autistic traits
Nonspecific dysmorphic facial features (See .)
Epilepsy, including generalized tonic-clonic seizures and absence seizures
Short stature
Strabismus
Brain MRI findings. The most common brain MRI findings are nonspecific but include:
Source: GeneReviews — "HNRNPU-Related Neurodevelopmental Disorder"
Because the phenotypic features associated with HNRNPU-related neurodevelopmental disorder are not sufficient to diagnose this condition, all disorders with epileptic encephalopathy and intellectual disability without other distinctive findings should be considered in the differential diagnosis. See OMIM Developmental and Epileptic Encephalopathy Phenotypic Series.
Source: GeneReviews — "HNRNPU-Related Neurodevelopmental Disorder"
Biomarker and diagnostic research for genetic developmental and epileptic encephalopathy has been reported in the published literature.
System/Concern | Evaluation | Comment |
|---|---|---|
Constitutional | Measurement of growth parameters | To incl weight, length/height, head circumference |
Neurologic | Neurologic eval | To incl brain MRI if unresolved/refractory seizures are present; Consider EEG if seizures are a concern. |
Development | Developmental assessment | To incl motor, adaptive, cognitive, speech/language eval; Eval for early intervention / special education Psychiatric/ |
Behavioral | Neuropsychiatric eval | For persons age 12 mos: screening for behavior concerns incl sleep disturbances, ADD, aggressive or destructive behaviors, /or traits suggestive of ASD Gastrointestinal/ |
Feeding | Gastroenterology/ nutrition/ feeding team eval | To incl eval of feeding ability nutritional status; Consider eval for swallowing dysfunction gastric tube placement in those w/dysphagia or continued poor growth on oral feedings alone.1 |
Cardiovascular | Echocardiogram | To assess valvular problems anatomic heart defects Respiratory/ |
Sleep | Evaluate for signs symptoms of sleep apnea | Consider polysomnogram if concerns about sleep disturbance or apnea. |
Eyes | Ophthalmologic eval | To assess for strabismus |
Hearing | Audiologic eval | To assess for hearing loss |
Genitourinary | Physical exam for undescended testes in males | Consider referral to urologist, if present. Consider renal ultrasound to assess for renal anomalies. |
Musculoskeletal | Orthopedics/ physical medicine rehab/ PT OT eval | To incl assessment of:; Gross motor fine motor skills; Mobility, ADL, need for adaptive devices; Need for PT (to improve gross motor skills) /or OT (to improve fine motor skills) Genetic |
counseling | By genetics professionals2 | To inform affected persons their families re nature, MOI, implications of HNRNPU-NDD to facilitate medical personal decision making Family support resources |
Treatment of Manifestations in Individuals with HNRNPU-Related Neurodevelopmental Disorder Manifestation/Concern | Treatment | Considerations/Other Hypotonia/ |
Hypertonia | Orthopedics / physical medicine rehab/ PT OT incl exercises to address muscle tone issues | Consider need for positioning mobility devices, disability parking placard. Consider involving appropriate specialists to aid in mgmt of baclofen, tizanidine, Botox®, or orthopedic procedures. |
Epilepsy | Standardized treatment w/ASM by experienced neurologist | Many ASMs may be effective; sodium valproate is the most commonly used effective medication.1; Ketogenic diet newer ASMs may be required for refractory seizures.; Education of parents/caregivers2 DD/ID / Behavioral |
issues | See . | Poor weight gain/ Failure |
to thrive | Feeding therapy; nasogastric or gastrostomy tube placement may be required for persistent feeding issues. | Low threshold for clinical feeding eval /or radiographic swallowing study if clinical signs or symptoms of dysphagia Congenital |
heart defects | Standard treatment per cardiologist | — |
Sleep apnea | In conjunction w/sleep specialist, appropriate treatment options may incl supplemental oxygen, CPAP, or BiPAP. | It is important to consider additional factors that may contribute to sleep apnea, incl opioids ASM. Hyperventilation/ Abnormal breathing |
patterns | Standard treatment per pulmonologist | Combined treatment w/acetazolamide, alprazolam, aripiprazole successfully used in 1 person.3 |
Strabismus | Standard treatment(s) per ophthalmologist | Hearing loss |
Source: GeneReviews — "HNRNPU-Related Neurodevelopmental Disorder"
Avoid activities and agents that may induce seizures, as the majority of affected individuals have a seizure disorder.
Source: GeneReviews — "HNRNPU-Related Neurodevelopmental Disorder"
Sustained single-dose gene therapy treatments for genetic forms of epilepsy, including HNRNPU-NDD, are currently being explored. This approach will be based on developing mRNA therapies and/or using a viral vector, such as AAV-9 (adeno-associated vector serotype 9), to deliver therapeutic protein to treat those forms of epilepsy caused by haploinsufficiency of proteins such as HNRNPU. Search ClinicalTrials.gov in the US and EU Clinical Trials Register in Europe for access to information on clinical studies for a wide range of diseases and conditions.
Source: GeneReviews — "HNRNPU-Related Neurodevelopmental Disorder"
View trials for genetic developmental and epileptic encephalopathy
| At each visit
| Monitor for constipation.
| • Monitor those w/seizures as clinically indicated.
Assess for new manifestations such as seizures changes in tone.
| Monitor developmental progress educational needs.
Psychiatric/
| Behavioral assessment for anxiety, attention, aggressive or self-injurious behavior
| Monitor for evidence of hyperventilation apnea.
| Physical medicine, OT/PT assessment of mobility, self-help skills
Family/
| Assess family need for social work support (e.g., palliative/respite care, home nursing, other local resources) care coordination.
Eyes | Ophthalmologic eval | Annually or as clinically indicated
| Audiologic eval
OT = occupational therapy; PT = physical therapy
Source: GeneReviews — "HNRNPU-Related Neurodevelopmental Disorder"
Laboratory research |
50 |
22% |
Disease patterns and progression | 35 | 15% |
Patient case studies | 29 | 13% |
Clinical study results | 13 | 6% |
New treatment approaches | 13 | 6% |
Testing and diagnosis research | 11 | 5% |
Other research | 2 | 1% |
Nguyen-Martinez AL (2026). [PMID: 41299892](https://pubmed.ncbi.nlm.nih.gov/41299892/). *Child Neuropsychol*. [Review / Meta-Analysis]
Wang Z (2026). [PMID: 41546957](https://pubmed.ncbi.nlm.nih.gov/41546957/). *Brain Dev*. [Review / Meta-Analysis]
Minderhoud CA (2026). [PMID: 41825261](https://pubmed.ncbi.nlm.nih.gov/41825261/). *Pediatr Neurol*. [Basic Science / Preclinical]
Ryvlin P (2026). [PMID: 41735792](https://pubmed.ncbi.nlm.nih.gov/41735792/). *Curr Opin Neurol*. [Review / Meta-Analysis]
Li J (2026). [PMID: 42216460](https://pubmed.ncbi.nlm.nih.gov/42216460/). *Rev Neurol*. [Case Report / Case Series]
Boeri S (2026). [PMID: 41724124](https://pubmed.ncbi.nlm.nih.gov/41724124/). *Epilepsy Behav*. [Case Report / Case Series]
Fasaludeen A (2026). [PMID: 41619470](https://pubmed.ncbi.nlm.nih.gov/41619470/). *Pediatr Neurol*. [Case Report / Case Series]
Liang XY (2026). [PMID: 41144712](https://pubmed.ncbi.nlm.nih.gov/41144712/). *Epilepsia*. [Basic Science / Preclinical]
Yang T (2026). [PMID: 41510908](https://pubmed.ncbi.nlm.nih.gov/41510908/). *Ann Neurol*. [Basic Science / Preclinical]
Reever CM (2026). [PMID: 41623181](https://pubmed.ncbi.nlm.nih.gov/41623181/). *J Clin Invest*. [Gene Therapy / Novel Therapeutics]
AI-curated news mentioning genetic developmental and epileptic encephalopathy
Updated Oct 26, 2026
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Washington, D.C. —October 2nd… Congressman Nick Langworthy today announced the introduction of the Biosimilars Access and Affordability Act, bipartisan legislation to expand access to lower-cost biosimilar prescription drugs and help bring them to market. Red tape should not stand between patients and affordable access to the cutting-edge treatments they need.” · The Biosimilars Access and Affordability Act is supported by the Alliance for Aging Research, Arthritis Foundation, Eosinophilic & Rare Disease Cooperative, Community Access National Network, Global Healthy Living Network, International Cancer Advocacy Network, International Pemphigus and Pemphigoid Foundation, Lupus and Allied Diseases Association, Inc., and Roswell Park. –Sarah Jones, Eosinophilic Rare Disease Coalition · Casey McPherson, Executive Director of the Alliance for Patient Access said, “Biosimilars give patients and physicians more affordable options for treating serious and chronic conditions. But unclear rules around Medicare's biosimilar delay provision are discouraging the investment needed to bring these treatments to market. The Biosimilars Access and Affordability Act restores the law's original intent with clear, predictable standards. This legislation is a pro-patient and pro-innovation solution to a harmful consequence of the IRA drug pricing negotiation program.” · Congressman Scott Peters said, “Biologics are critical to treating serious illnesses like cancer, autoimmune diseases and genetic disorders, but they are also some of the most expensive drugs on the market. Congressman Nick Langworthy today announced the introduction of the Biosimilars Access and Affordability Act, bipartisan legislation to expand access to lower-cost biosimilar prescription drugs and help bring them to market. The legislation updates Medicare policy to provide a clearer pathway for lower-cost biosimilar medicines that are actively moving toward the market, while protecting Medicare if those anticipated competitors never reach patients.