Understanding theNAA15 Gene
A deep dive into the genetics, biology, and clinical presentation of NAA15-related neurodevelopmental disorder.
What is the NAA15 Gene?
NAA15 (N-alpha-acetyltransferase 15) encodes the auxiliary subunit of the NatA Complex. This complex is responsible for the co-translational acetylation of the N-terminus of approximately 40% of all human proteins — a critical Post-Translational Modification essential for protein stability, folding, and function.
The NAA15 gene is located on chromosome Chromosome 4q22.1. It works in partnership with NAA10, the catalytic subunit of the NatA complex. When NAA15 is disrupted by a Pathogenic Variant, the entire NatA complex is destabilized, leading to widespread dysregulation of protein acetylation during brain development.
This disruption is believed to impair neuronal migration, synaptic development, and cortical organization — explaining the broad neurodevelopmental Phenotype observed in affected individuals.
Inheritance Pattern
De Novo: Not Inherited
Many NAA15 cases arise from De Novo Mutations — spontaneous changes in the DNA that occur for the first time in the affected individual and are not present in either parent. Inherited cases have also been reported, so the inheritance pattern is not exclusively de novo. This is a critical distinction that has profound implications for Genetic Counseling.
Because the mutation is de novo, parents who have one child with NAA15 have a very low recurrence risk (approximately 1%, due to the possibility of Gonadal Mosaicism) for future pregnancies. However, an affected individual who has children would have a 50% chance of passing the variant to each child — consistent with Autosomal Dominant inheritance.
This is precisely why Trio-WES — testing the child and both biological parents simultaneously — is the recommended diagnostic approach. It confirms the de novo nature of the variant and rules out inherited causes.
How NAA15 Affects Patients
NAA15 presents with a broad spectrum of neurodevelopmental features. No two individuals are affected in exactly the same way, but common patterns emerge across the patient population.
Cognitive Development
Intellectual Disability (ID) is present in virtually all individuals (~100%), ranging from mild to severe. Severity varies even between individuals with the same variant — a hallmark of Variable Expressivity. Early educational intervention significantly improves outcomes.
Speech & Language
Speech and language delay affects ~97% of individuals. Expressive language is typically more impaired than receptive. Many children benefit from Augmentative and Alternative Communication (AAC) devices. Early speech therapy is strongly recommended.
Behavioral Health
Autism Spectrum Disorder (ASD) features and behavioral challenges are reported in ~91% of individuals (Cheng et al., 2018). Social communication difficulties, repetitive behaviors, and sensory sensitivities are frequently observed. Formal ASD evaluation is recommended at diagnosis.
Motor Function
Motor delay affects ~97% of individuals. Hypotonia (low muscle tone) is present in ~39%. Children may be late to sit, stand, and walk. Physical and occupational therapy help build strength and coordination. Some children show meaningful catch-up with early intervention.
Neurological
Seizures occur in approximately 23–31% of individuals. EEG (Electroencephalogram) abnormalities may be present even without clinical seizures. Expert neuroimaging review reveals an average of 2.8 brain anatomical abnormalities per individual, even when routine MRI is reported as normal (Patel et al., 2024).
Cardiac & Other Systems
Congenital Heart Disease (CHD) is reported in ~21% of individuals, including structural defects and Hypertrophic Cardiomyopathy (HCM). Feeding difficulties affect ~57%. Vision problems including strabismus and Cortical Visual Impairment (CVI) have also been documented. Cardiac evaluation at diagnosis is strongly advisable.
NAA15 Discovery Timeline
Cheng et al. published the landmark paper in AJHG identifying NAA15 as a distinct neurodevelopmental syndrome in 38 individuals from 33 unrelated families across 15+ institutions in the US, Netherlands, UK, Australia, Belgium, France, Italy, Canada, and Norway. Both de novo and inherited inheritance patterns were documented.
Concurrent structural and functional studies (Arnesen lab, University of Bergen) detailed how NAA15 variants destabilize the NatA N-terminal acetyltransferase complex, disrupting co-translational acetylation of approximately 40% of all human proteins.
International phenotypic and biochemical analysis of individuals with variants in NAA10 and NAA15 confirmed variable expressivity — severity can differ even between individuals with the same variant within the same family.
Ward et al. published in Circulation Research detailing the molecular mechanisms of congenital heart disease caused by NAA15 haploinsufficiency, prompting routine cardiology evaluation at diagnosis. Simons Searchlight launched a dedicated NAA15 natural history registry.
Chinese cohort study (Tian et al., Capital Institute of Pediatrics, Beijing) screened 769 NDD children and documented possible catch-up developmental trajectories in 3 of 4 NAA15 patients with early physical rehabilitation — an important prognostic finding.
Lyon et al. (Nature/EJHG) expanded the known phenotypic spectrum across a larger international cohort. ERN ITHACA (European Reference Network) launched a call for collaboration on NAA15 beyond childhood, recognizing a critical gap in adult phenotype data.
Makwana et al. published the most comprehensive natural history study through adolescence using Simons Searchlight registry data. Patel et al. published the first dedicated neuroimaging analysis, finding an average of 2.8 brain anatomical abnormalities per NAA15 individual on expert review.
Why Did We Make This Website?
My son Logan (the beautiful little guy seen above and throughout this site) was diagnosed with NAA15 just before his second birthday after a long and difficult search for answers. What began as concerns about developmental delays quickly turned into something much more complex — including Hypotonia (low muscle tone), a heart anomaly, macrocephaly, visual impairment, and a risk of Seizures. At one point, his symptoms even pointed solely toward mitochondrial disease, adding to the uncertainty.
We have also faced periods of real fear and uncertainty around his health, including difficult conversations about life expectancy — which have been some of the hardest parts of this journey. Logan is also diagnosed with Level 3 Autism Spectrum Disorder (ASD) and is nonverbal, requiring significant full-time support.
Like many families, we spent countless hours at doctor visits, often feeling dismissed or told to wait and see. We had to push, advocate, and fight to get the testing, diagnosis, and services he needed. Along the way, one of the biggest challenges was how difficult it was to find clear, reliable information.
That experience is what led me to create NAA15.org. My goal is to provide a place where families and medical professionals can access accurate, research-based information in one location, with sources clearly cited and explained.
This site was built to make the journey a little easier for others — and to help improve understanding, awareness, and care for those affected by NAA15.
Ready to learn about symptoms?
Understanding the full clinical picture of NAA15 is the first step toward getting the right diagnosis.