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PubMed This is a summary of 30 peer-reviewed journal articles Updated
Genetics

Understanding the 15q13.3 Diagnosis: A Guide for Parents

At a Glance

15q13.3 microdeletion syndrome is a variable genetic condition that acts as a vulnerability factor, not a fixed destiny. Because of incomplete penetrance, many people carry the deletion without any symptoms, and the condition does not cause a progressive loss of developmental skills.

Receiving a genetic diagnosis for your child can feel like being handed a map to a place you never intended to visit. It is completely normal to feel overwhelmed, confused, or even grief-stricken. You are not alone in this journey. Reaching out to rare chromosome disorder support networks (such as UNIQUE) can help combat feelings of isolation. While 15q13.3 microdeletion syndrome is rare, understanding the basic “rules” of this condition can help you feel more grounded as you advocate for your child.

Stabilizing Facts for Families

  • The Future is Not Pre-Written: Because this syndrome is highly variable, your child’s diagnosis does not dictate their entire future potential [1][2].
  • No Universal Regression: Unlike some genetic conditions where children lose skills they have already gained, 15q13.3 microdeletion syndrome is not characterized by developmental regression or progressive brain decline [3][1].
  • A “Disease Primer,” Not a Guarantee: Modern research views this deletion more as a “vulnerability factor” or “disease primer” rather than a fixed destiny; it may increase the risk for certain challenges, but it does not make them inevitable [4][5].

What is 15q13.3 Microdeletion Syndrome?

A microdeletion means that a tiny piece of genetic material is missing from one of the body’s chromosomes—in this case, chromosome 15 at a specific location labeled “q13.3” [6]. Think of a chromosome like a long instruction manual; a microdeletion is like a few missing sentences or a short paragraph. Although the missing piece is small, it often contains several genes that are important for brain development and function, such as the CHRNA7 gene [7][8].

This condition is rare, with current estimates suggesting it occurs in approximately 1 in 2,500 to 1 in 5,525 births [9][10]. Because many people with the deletion have no symptoms at all, it may be more common than previously thought and only discovered when a family member is tested [2].

Understanding “Incomplete Penetrance”

One of the most confusing parts of this diagnosis is that some people with the exact same 15q13.3 deletion have no medical or developmental problems at all [1][11]. Doctors call this incomplete penetrance.

  • Penetrance refers to whether the “instruction manual error” actually shows up as a symptom in the person.
  • Incomplete means that not everyone who carries the deletion will “penetrate” or express the condition. In fact, it is common to find a parent who carries the deletion but has never had a single symptom, only to have it discovered after their child is diagnosed [2][11].

Understanding “Variable Expressivity”

Even when the deletion does cause symptoms, those symptoms vary wildly from person to person—a concept called variable expressivity [6][12]. Within the same family, one person might have mild learning struggles, while another might have epilepsy or autism [1][13].

Commonly observed features can include:

  • Intellectual or learning disabilities: Ranging from very mild to more significant [14].
  • Epilepsy: Specifically absence seizures, which may look like brief “staring spells” [6].
  • Behavioral health: Increased rates of ADHD, autism spectrum disorder, or anxiety [15][13].
  • Low muscle tone (hypotonia): Which might make a child appear “floppy” or reach physical milestones like walking a bit later [6].

Because of this variability, your child’s care team will focus on your child’s specific strengths and needs rather than a “one-size-fits-all” treatment plan. This diagnosis is a tool to help you access the right support, like speech therapy or educational accommodations, earlier than you might have otherwise [1][3].

For more detailed information, please read the specific guides on:

01

Symptoms & Lifespan Journey: What to Expect

Learn what to expect with 15q13.3 microdeletion syndrome from childhood through adulthood, including developmental delays, seizure risks, and mental health.

02

The Biology of the Deletion: Genes and Inheritance

Understand the genetics of 15q13.3 microdeletion syndrome. Learn how the CHRNA7 and OTUD7A genes work, inheritance patterns, and what reduced penetrance means.

03

Building Your Care Team and Managing Symptoms

Learn how to build a medical care team and manage symptoms for 15q13.3 microdeletion syndrome. Discover recommended baseline tests like EEGs and therapies.

Common questions in this guide

What does a 15q13.3 microdeletion diagnosis mean for my child's future?
Because 15q13.3 microdeletion syndrome is highly variable, the diagnosis does not dictate your child's entire future. It acts more as a vulnerability factor than a strict disease, and symptoms can range from non-existent to more significant challenges like seizures or learning delays.
What is incomplete penetrance in 15q13.3 microdeletion syndrome?
Incomplete penetrance means that a person can have the missing piece of chromosome 15 but never develop any symptoms. It is very common for a parent to carry the deletion without knowing it until their child is diagnosed.
Will my child lose skills they have already learned?
No, 15q13.3 microdeletion syndrome is not characterized by developmental regression or a progressive decline in brain function. Children with this condition do not typically lose the developmental milestones they have successfully reached.
Should my child be tested for seizures if they seem fine?
Children with this deletion have an increased risk of epilepsy, particularly absence seizures which can look like brief staring spells. Your doctor may recommend a baseline EEG to screen for these silent seizures even if you have not noticed any obvious signs.
What is the CHRNA7 gene and why is it important?
The CHRNA7 gene is an important set of instructions for brain development located in the 15q13.3 region. When this tiny piece of genetic material is missing, the absence of the CHRNA7 gene is believed to contribute to the neurodevelopmental symptoms sometimes seen in the syndrome.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Given the high variability of this syndrome, what specific neurodevelopmental milestones should we be monitoring most closely for my child?
  2. 2.Does my child's specific deletion include the CHRNA7 gene, and how does that influence their clinical outlook?
  3. 3.Should we schedule a baseline EEG to screen for silent or absence seizures, even if we haven't noticed any?
  4. 4.Would you recommend genetic testing for the biological parents to see if this deletion was inherited or occurred de novo?
  5. 5.What local early intervention resources or specialists do you recommend for children with 15q13.3 microdeletions?

Questions For You

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References

References (15)
  1. 1

    The complex behavioral phenotype of 15q13.3 microdeletion syndrome.

    Ziats MN, Goin-Kochel RP, Berry LN, et al.

    Genetics in medicine : official journal of the American College of Medical Genetics 2016; (18(11)):1111-1118 doi:10.1038/gim.2016.9.

    PMID: 26963284
  2. 2

    Genetic counseling of prenatally detected familial 15q13.2q13.3 microdeletion encompassing CHRNA7 and OTUD7A with asymptomatic carriers in the family.

    Chen CP, Wu FT, Pan YT, et al.

    Taiwanese journal of obstetrics & gynecology 2025; (64(2)):361-363 doi:10.1016/j.tjog.2024.12.015.

    PMID: 40049827
  3. 3

    Heterozygous Deletion of Chromosome 15q13.3 in a Boy with Developmental Regression, Global Developmental Delay, Hypotonia, and Short Stature.

    Strauss AM, Buhle AC, Finkler DM

    Pediatric reports 2022; (14(4)):528-532 doi:10.3390/pediatric14040061.

    PMID: 36548204
  4. 4

    Interactive effects between hemizygous 15q13.3 microdeletion and peripubertal stress on adult behavioral functions.

    Giovanoli S, Werge TM, Mortensen PB, et al.

    Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology 2019; (44(4)):703-710 doi:10.1038/s41386-018-0189-3.

    PMID: 30188511
  5. 5

    Central and peripheral immune responses to low-dose lipopolysaccharide in a mouse model of the 15q13.3 microdeletion.

    Halawa AA, Rees KA, McCamy KM, Winzer-Serhan UH

    Cytokine 2020; (126()):154879 doi:10.1016/j.cyto.2019.154879.

    PMID: 31629107
  6. 6

    The spectrum of epilepsy in children with 15q13.3 microdeletion syndrome.

    Whitney R, Nair A, McCready E, et al.

    Seizure 2021; (92()):221-229 doi:10.1016/j.seizure.2021.09.016.

    PMID: 34601452
  7. 7

    Network Effects of the 15q13.3 Microdeletion on the Transcriptome and Epigenome in Human-Induced Neurons.

    Zhang S, Zhang X, Purmann C, et al.

    Biological psychiatry 2021; (89(5)):497-509 doi:10.1016/j.biopsych.2020.06.021.

    PMID: 32919612
  8. 8

    Impaired OTUD7A-dependent Ankyrin regulation mediates neuronal dysfunction in mouse and human models of the 15q13.3 microdeletion syndrome.

    Unda BK, Chalil L, Yoon S, et al.

    Molecular psychiatry 2023; (28(4)):1747-1769 doi:10.1038/s41380-022-01937-5.

    PMID: 36604605
  9. 9

    An estimation of the prevalence of genomic disorders using chromosomal microarray data.

    Gillentine MA, Lupo PJ, Stankiewicz P, Schaaf CP

    Journal of human genetics 2018; (63(7)):795-801 doi:10.1038/s10038-018-0451-x.

    PMID: 29691480
  10. 10

    Population prevalence and inheritance pattern of recurrent CNVs associated with neurodevelopmental disorders in 12,252 newborns and their parents.

    Smajlagić D, Lavrichenko K, Berland S, et al.

    European journal of human genetics : EJHG 2021; (29(1)):205-215 doi:10.1038/s41431-020-00707-7.

    PMID: 32778765
  11. 11

    15q13.3 duplication in two patients with childhood-onset schizophrenia.

    Zhou D, Gochman P, Broadnax DD, et al.

    American journal of medical genetics. Part B, Neuropsychiatric genetics : the official publication of the International Society of Psychiatric Genetics 2016; (171(6)):777-83 doi:10.1002/ajmg.b.32439.

    PMID: 26968334
  12. 12

    The 15q13.3 deletion syndrome: Deficient α(7)-containing nicotinic acetylcholine receptor-mediated neurotransmission in the pathogenesis of neurodevelopmental disorders.

    Deutsch SI, Burket JA, Benson AD, Urbano MR

    Progress in neuro-psychopharmacology & biological psychiatry 2016; (64()):109-17.

    PMID: 26257138
  13. 13

    Rapid-Onset Obesity Due to Impulsive Food-Seeking Behavior in a Puerto Rican Child With CHRNA7 15q13.3 Microdeletion.

    Jiménez BL, Carlo S, De Jesús Rojas W

    Cureus 2021; (13(3)):e14012 doi:10.7759/cureus.14012.

    PMID: 33884253
  14. 14

    Atypical Prader-Willi and 15q13.3 Microdeletion Syndromes in a Patient with an Unbalanced Translocation.

    Colovati MES, Grossi BM, Nunes GD, et al.

    Cytogenetic and genome research 2019; (158(4)):192-198 doi:10.1159/000501753.

    PMID: 31394532
  15. 15

    Chromosome 15q BP4-BP5 Deletion in a Girl with Nocturnal Frontal Lobe Epilepsy, Migraine, Circumscribed Hypertrichosis, and Language Impairment.

    Pavone P, Pappalardo XG, Ohazuruike UNN, et al.

    Journal of epilepsy research 2020; (10(2)):84-91 doi:10.14581/jer.20014.

    PMID: 33659201

This page provides educational information about 15q13.3 microdeletion syndrome for parents. Always consult a pediatric geneticist or neurologist to interpret how this diagnosis specifically affects your child.

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