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A clinical reference for physicians, geneticists, neurologists, and pediatricians encountering NAA15-related neurodevelopmental disorder — whether pursuing a first-time diagnosis or managing an established case.
2018
First described (Cheng et al., AJHG)
38+
Individuals in landmark cohort
~1%
Parental recurrence risk (gonadal mosaicism)
Trio-WES
Recommended diagnostic test
Clinical Awareness Notice
Factitious Disorder Imposed on Another (FDIA) — Context for Rare Disease Clinicians
Clinicians evaluating children with complex, multi-system presentations — including those on the path to a rare genetic diagnosis such as NAA15 — should be aware of Factitious Disorder Imposed on Another (FDIA), formerly known as Munchausen Syndrome by Proxy. This notice is provided in the interest of complete clinical awareness. It is not a suggestion that NAA15 families are suspect — the vast majority are not. It is a reminder that FDIA exists, is rare, and that the diagnostic journey for rare diseases can sometimes intersect with FDIA concerns in ways that require careful, evidence-based clinical judgment.
What Is FDIA?
- FDIA is a recognized form of medical child abuse in which a caregiver fabricates or induces illness in a child to gain medical attention.
- It is classified in DSM-5 and ICD-11 as a factitious disorder.
- Estimated prevalence: 0.5 to 2 per 100,000 children — making it genuinely rare.
- Mortality in confirmed FDIA cases has been reported at 6–10%, making early identification critical when it is present.
- FDIA is distinct from a parent who is anxious, persistent, or well-informed about their child's condition.
The Rare Disease Context — A Critical Balance
- Rare disease diagnoses — including NAA15 — are frequently delayed by years. Long diagnostic journeys are the norm, not a red flag.
- Parents of children with rare diseases often become highly knowledgeable advocates. This is appropriate and should not be conflated with fabrication.
- FDIA accusations in children with mitochondrial and other rare diseases have been documented as a serious concern — some families have faced false accusations during legitimate diagnostic workups.
- Misapplication of FDIA suspicion in complex rare disease cases can cause significant harm: delayed diagnosis, family separation, and loss of trust in the medical system.
- Clinicians should apply objective, evidence-based criteria when FDIA is considered — not pattern-match on parental persistence or medical complexity alone.
0.5–2
per 100,000 children
(estimated FDIA prevalence)
6–10%
mortality in confirmed
FDIA cases (PMC5915702)
Years
average diagnostic delay
for rare genetic disorders
Clinical guidance: When FDIA is genuinely suspected, consult your institution's child protection team and follow established protocols. Do not allow FDIA suspicion to delay genetic testing in a child with a legitimate complex presentation. A confirmed genetic diagnosis — such as NAA15 — is definitive evidence against fabrication of that condition. Source references: Cleveland Clinic FDIA; PMC5915702; MitoAction.
Pathophysiology at a Glance
NAA15 (N-alpha-acetyltransferase 15, chromosome 4q22.1) encodes the auxiliary subunit of the NatA Complex — the most abundant N-terminal acetyltransferase in human cells. NatA co-translationally acetylates the N-terminus of approximately 40% of all human proteins, a modification critical for protein stability, folding, localization, and degradation.
NAA15 serves as the ribosome-anchoring subunit, positioning the catalytic partner NAA10 to acetylate nascent polypeptides as they emerge from the ribosome. Pathogenic variants in NAA15 cause Haploinsufficiency — destabilizing the entire NatA complex and impairing downstream acetylation of hundreds of substrate proteins.
The downstream effects are particularly severe during neurodevelopment, when precise protein regulation is essential for neuronal migration, synaptic formation, and cortical organization — explaining the broad and variable Phenotype.
Variant types include loss-of-function (truncating), missense, frameshift, and splice-site variants. Most cases are De Novo Mutation — not present in either parent — though inherited cases have been documented. Inheritance follows an Autosomal Dominant pattern.
Gene Location
Chromosome 4q22.1
Gene Function
Auxiliary subunit of NatA N-terminal acetyltransferase complex
Proteins Affected
~40% of all human proteins require NatA acetylation
Inheritance
Autosomal dominant; most often de novo; inherited cases documented
Parental Recurrence Risk
~1% (gonadal mosaicism); parents typically unaffected
Variant Types
Loss-of-function, missense, frameshift, splice-site
First Described
2018, Cheng et al., AJHG (PMID 29656860)
Cohort Size
38 individuals, 33 families, 15+ international institutions (2018)
Phenotypic Profile
Frequencies from Cheng et al. (2018), the foundational international cohort of 38 individuals. Variable expressivity is a hallmark — severity differs even between individuals with the same variant.
Intellectual Disability
~100%Ranges from mild to severe. Severity varies even between individuals carrying the same variant — a hallmark of variable expressivity. Formal neuropsychological evaluation recommended.
Speech & Language Delay
~97%Expressive language typically more impaired than receptive. Many individuals remain minimally verbal or nonverbal. Early AAC evaluation strongly recommended.
Motor Delay
~97%Gross and fine motor delays. Hypotonia present in ~39%. Late achievement of sitting, standing, and walking milestones. Physical and occupational therapy improve outcomes.
Autism Spectrum Features / Behavioral
~91%ASD features including social communication difficulties, repetitive behaviors, and sensory sensitivities. Formal ASD evaluation recommended at diagnosis. Level 3 ASD (requiring substantial support) is not uncommon.
Seizures / Epilepsy
~23–31%Multiple seizure types reported (absence, focal, tonic-clonic). EEG abnormalities may be present without clinical seizures. Neurology referral and EEG at diagnosis recommended.
Congenital Heart Disease
~21%Structural defects and hypertrophic cardiomyopathy (HCM) documented. Cardiac evaluation including echocardiography at diagnosis is strongly advisable. HCM carries arrhythmia risk if unmanaged.
Feeding Difficulties
~57%Oral motor dysfunction, poor suck/swallow coordination in infancy. Aspiration risk. Feeding therapy and dietitian involvement recommended. G-tube placement in severe cases.
Dysmorphic Features
~64%Variable and non-specific. May include broad nasal bridge, prominent forehead, widely spaced eyes, prominent chin, and macrocephaly. Dysmorphology alone is insufficient for diagnosis.
Ophthalmic Findings
VariableCortical visual impairment (CVI), strabismus, and refractive errors documented (Patel et al., 2024). Ophthalmology evaluation recommended, particularly in nonverbal individuals.
Variable Expressivity — Key Clinical Point
Severity varies significantly even between individuals carrying the same pathogenic variant, including within the same family. A mildly affected parent may not have received a prior diagnosis. This has direct implications for genetic counseling and cascade testing. Source: Cheng et al. 2019, PMC6736318.
Diagnostic Workup & Management
Genetic Testing — First-Line
Trio-WES (Gold Standard)
Whole Exome Sequencing of proband + both biological parents simultaneously. Confirms de novo vs. inherited status. Most efficient path to diagnosis. Recommended by ACMG guidelines for unexplained NDD.
Proband WES / WGS
If trio testing is not feasible. Whole Genome Sequencing may identify intronic or regulatory variants missed by exome sequencing.
Targeted Gene Panel
NDD/ID gene panels may include NAA15. Less comprehensive than WES/WGS but faster and lower cost. May miss novel variants.
Chromosomal Microarray
Does NOT diagnose NAA15 (single-nucleotide variants). Useful to rule out copy number variants as a concurrent or alternative diagnosis.
Cardiac Evaluation
Echocardiography
At diagnosis and periodically thereafter. Hypertrophic cardiomyopathy (HCM) and structural defects documented in ~21% of individuals. HCM may be asymptomatic.
ECG / Holter Monitor
Arrhythmia screening, particularly in individuals with known HCM or unexplained syncope.
Cardiology Referral
Pediatric cardiology co-management recommended at diagnosis regardless of initial echocardiogram result.
Neurological Evaluation
EEG
At diagnosis and when seizures are suspected. EEG abnormalities may be present without clinical seizures. Seizures occur in ~23–31% of individuals.
Brain MRI
Recommended. Note: routine clinical MRI is often reported as 'normal.' Expert neuroradiological review reveals an average of 2.8 anatomical abnormalities per NAA15 individual (Patel et al., 2024). Findings include pons volume changes, white matter lesions, and mild 4th ventricle enlargement.
Neurology Referral
For seizure management, EEG interpretation, and neuroimaging review. Ongoing follow-up recommended.
Developmental & Behavioral
Formal Developmental Assessment
Vineland Adaptive Behavior Scales, Bayley Scales, or equivalent. Establishes baseline and guides therapy planning.
ASD Evaluation
ADOS-2 / ADI-R or equivalent. ASD features present in ~91% of individuals. Formal diagnosis enables access to services and supports.
Speech-Language Pathology
Early referral. AAC evaluation for nonverbal or minimally verbal individuals. Feeding evaluation if oral motor concerns present.
Occupational & Physical Therapy
For motor delays, hypotonia, fine motor deficits, and sensory processing. Early intervention improves outcomes.
Additional Evaluations
Ophthalmology
Cortical visual impairment, strabismus, and refractive errors documented. Particularly important in nonverbal individuals who cannot self-report visual symptoms.
Audiology
Hearing evaluation to rule out concurrent hearing loss contributing to speech delay.
Feeding / GI
Dietitian and feeding therapy referral for feeding difficulties (~57%). Aspiration risk assessment. Consider modified barium swallow study if aspiration suspected.
Genetics / Genetic Counseling
Confirm variant pathogenicity classification. Discuss recurrence risk (~1% for parents due to gonadal mosaicism; 50% for affected individual if they have children). Offer cascade testing.
Tests That Cannot Diagnose NAA15
Standard clinical tests — brain MRI, EEG, chromosomal microarray, metabolic panels, and standard blood tests — may all return normal results in an individual with NAA15. Genetic sequencing is required for confirmation.
Databases & Professional Resources
Verified clinical databases, registries, and professional resources for NAA15.
Inheritance & Recurrence Risk
De Novo (Most Common)
- Variant arises spontaneously in the proband — not present in either parent
- Parental recurrence risk: ~1% (gonadal mosaicism)
- Trio-WES confirms de novo status
- Affected individual: 50% transmission risk to each child (autosomal dominant)
Inherited (Documented)
- Inherited cases documented — parent may be mildly or subclinically affected
- Variable expressivity means a parent may not have received a prior diagnosis
- Cascade testing of parents and siblings recommended
- If parent is a carrier: 50% recurrence risk for each subsequent pregnancy
Counseling Points Summary
Life Expectancy & Long-Term Outlook
NAA15 is not described as a life-limiting condition in the published literature. Adults are documented in published cohorts. No pattern of premature mortality has been established. However, cardiac and neurological complications require active monitoring.
Cardiac Anomalies (~21%)
Moderate–HighHCM and structural defects are the most significant life-affecting variables. Unmanaged HCM carries arrhythmia and sudden cardiac event risk. When identified and managed, most cardiac conditions are treatable. Routine echocardiography at diagnosis and regular cardiology follow-up are strongly recommended.
Ward et al., Circ Res 2021; Ritter et al., PMC8007079
Seizures / Epilepsy (~23–31%)
ModerateMultiple seizure types (absence, focal, tonic-clonic). Most manageable with anti-seizure medications. SUDEP risk not specifically documented in NAA15 cohorts but applies to poorly controlled epilepsy generally. EEG monitoring and neurology follow-up are standard care.
Cheng et al., AJHG 2018; Makwana et al., AJMG 2024
Intellectual Disability (~100%)
LifelongDoes not directly shorten lifespan but affects independence and self-management of health. Adults with intellectual disability have higher rates of undetected health conditions — underscoring the importance of ongoing specialist care into adulthood.
ERN ITHACA Adult Phenotype Initiative, 2023
Vision & Neurological Complications
VariableCVI, strabismus, and subtle brain anatomical findings (avg. 2.8 abnormalities on expert MRI review) documented. Do not typically affect lifespan but affect quality of life and safety. Regular ophthalmology and neurology follow-up recommended.
Patel et al., PMC11230317 & PMC10862986, 2024
Data Limitation: NAA15 was first described in 2018. Published cohorts are small and skewed toward children and adolescents. No large-scale adult mortality data exists for NAA15 specifically. ERN ITHACA launched a dedicated adult phenotype initiative in 2023 to address this gap. Clinicians should discuss prognosis directly with families based on individual clinical findings.
Enroll Your Patient in Simons Searchlight
Simons Searchlight runs the primary NAA15 natural history registry. Enrolling patients contributes longitudinal data that directly advances research and improves clinical understanding. Enrollment is free and open internationally.
International enrollment — open to clinicians worldwide
Longitudinal natural history data collection
Connects families with the global NAA15 research community
IRB-approved protocol; patient privacy protected
Medical Disclaimer: This page is intended as an educational reference for medical professionals and does not constitute clinical guidelines or replace specialist consultation. All clinical decisions should be made in the context of the individual patient. Content is based on published peer-reviewed literature and trusted rare disease databases as cited. NAA15 was first described in 2018; the evidence base continues to evolve. Clinicians are encouraged to consult the primary literature and refer to a clinical geneticist for complex cases.