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PubMed This is a summary of 26 peer-reviewed journal articles Updated
Pediatrics · 18p Deletion Syndrome

Building a Foundation: Understanding 18p Deletion Syndrome

At a Glance

18p deletion syndrome (Monosomy 18p) is a rare genetic condition caused by a missing piece of chromosome 18. While symptoms vary widely, children typically have a normal life expectancy. Common challenges like growth issues and low muscle tone are highly treatable with specialized therapies.

Receiving a diagnosis of 18p deletion syndrome (also known as Monosomy 18p) can feel overwhelming, especially because it is so rare that you may never have heard of it before [1]. It is natural to feel a mix of shock, grief, or even relief at finally having an answer. Your feelings are a valid part of this journey as you begin to navigate this new path for your child.

Understanding the Diagnosis

18p deletion syndrome is a genetic condition where a piece of the short arm (the “p” arm) of the 18th chromosome is missing [2]. Because this occurs in approximately 1 in 50,000 live births, it is considered a very rare disease [1]. It is highly likely that your local pediatrician has never treated a child with this specific syndrome. This does not mean your child cannot receive excellent care; it simply means your medical team will need to consult with specialists and rare-disease resources to provide the best support.

Three Stabilizing Facts

When you first receive this news, it can feel like the future is uncertain. Here are three evidence-based facts to help ground your perspective:

  1. Life Expectancy is Typically Normal: For the vast majority of children with 18p-, life expectancy is not reduced. They are expected to live full lives into adulthood [3][4].
  2. Symptoms are Highly Variable: No two children with 18p- are exactly alike [5]. This means your child will have their own unique strengths and challenges; they may not experience every symptom you read about.
  3. Effective Treatments Exist: While there is no “cure” for a chromosomal deletion, many of the symptoms are highly treatable. For example, growth hormone deficiency is common in 18p-, and growth hormone therapy is a standard treatment that effectively improves height and growth [6]. Early intervention therapies—such as physical, occupational, and speech therapy—are also crucial and effective [7].

Early Childhood Presentations

In the first few years of life, you may notice certain common features associated with 18p-. These can include:

  • Physical Features: Subtle differences such as a round face, ptosis (drooping eyelids), a wide mouth, or low-set ears [6][2].
  • Tone and Feeding: Infants often have hypotonia (low muscle tone), which can lead to feeding and swallowing difficulties early on, as well as delayed motor milestones like sitting and walking [2][7].
  • Growth Issues: Many children are shorter than their peers due to endocrine abnormalities [6].

Managing the Future

Management of 18p- is focused on the individual child’s needs. This often involves a multidisciplinary team, including a geneticist, an endocrinologist to monitor growth and hormones, and neurologists [6][7]. There is also an increased susceptibility to autoimmune issues and certain immune deficiencies, which your team will want to monitor over time [8][9].

To dive deeper into your child’s diagnosis and care plan, explore the following pages:

01

The Genetics of 18p Deletion: Understanding the Missing Piece

Understand the genetics of 18p deletion syndrome. Learn about key genes like TGIF1, haploinsufficiency, and how to read your child's CMA test results.

02

Symptoms, Development & Growth: What to Expect

Learn what to expect with 18p deletion syndrome (Monosomy 18p) development. Understand common physical traits, cognitive delays, and neurological symptoms.

03

Standard of Care: Endocrine Management, Therapies & Screening

Learn the standard of care for Monosomy 18p syndrome (18p deletion), including endocrine management, growth hormone therapy, essential screenings, and therapies.

04

Building Your Child's Care Team & Preparing for Visits

Learn how to build a medical care team for 18p deletion syndrome (Monosomy 18p). Discover which specialists your child needs and how to prepare for visits.

Common questions in this guide

What is the life expectancy for a child with 18p deletion syndrome?
For the vast majority of children with 18p deletion syndrome, life expectancy is not reduced. They are generally expected to live full, active lives into adulthood.
What are the early signs of 18p deletion syndrome in babies?
Infants often have low muscle tone, which can cause early feeding and swallowing difficulties. You may also notice physical differences like drooping eyelids or low-set ears, as well as delayed milestones like sitting and walking.
Is there a treatment or cure for 18p deletion syndrome?
While the missing chromosome cannot be replaced, many specific symptoms are highly treatable. Standard care often includes growth hormone therapy to improve height, alongside early physical, occupational, and speech therapies to support development.
Why does my child need to see an endocrinologist for an 18p deletion?
Children with 18p deletion syndrome frequently experience endocrine abnormalities, most commonly growth hormone deficiency. A pediatric endocrinologist can test for these imbalances and prescribe treatments to help your child grow appropriately.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Can you refer us to a pediatric endocrinologist to test for growth hormone deficiency?
  2. 2.What specific chromosomal breakpoints were identified in my child's genetic testing?
  3. 3.What early intervention services (PT, OT, speech) do you recommend starting immediately?

Questions For You

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

References

References (9)
  1. 1

    Prenatal diagnosis of de novo monosomy 18p deletion syndrome by chromosome microarray analysis: Three case reports.

    Qi H, Zhu J, Zhang S, et al.

    Medicine 2019; (98(14)):e15027 doi:10.1097/MD.0000000000015027.

    PMID: 30946338
  2. 2

    Spectrum of Movement Disorders in 18p Deletion Syndrome.

    Crosiers D, Blaumeiser B, Van Goethem G

    Movement disorders clinical practice 2019; (6(1)):70-73 doi:10.1002/mdc3.12707.

    PMID: 30746419
  3. 3

    Trisomy 20p/monosomy 18p associated with congenital bilateral perisylvian syndrome.

    Bonardi CM, Bayat A, Madsen CG, et al.

    Epileptic disorders : international epilepsy journal with videotape 2022; (24(3)):577-582 doi:10.1684/epd.2022.1423.

    PMID: 35770758
  4. 4

    18p Deletion Syndrome: Case Report with Clinical Consideration and Management.

    Goyal M, Jain M, Singhal S, Nandimath K

    Contemporary clinical dentistry 2017; (8(4)):632-636 doi:10.4103/ccd.ccd_129_17.

    PMID: 29326517
  5. 5

    The genotype and phenotype of chromosome 18p deletion syndrome: Case series.

    Jin Q, Qiang R, Cai B, et al.

    Medicine 2021; (100(18)):e25777 doi:10.1097/MD.0000000000025777.

    PMID: 33950970
  6. 6

    A case of de novo 18p deletion syndrome with panhypopituitarism.

    Yang A, Kim J, Cho SY, et al.

    Annals of pediatric endocrinology & metabolism 2019; (24(1)):60-63 doi:10.6065/apem.2019.24.1.60.

    PMID: 30943682
  7. 7

    Anterior Pituitary Aplasia in an Infant with Ring Chromosome 18p Deletion.

    Bellfield EJ, Chan J, Durrin S, et al.

    Case reports in endocrinology 2016; (2016()):2853178 doi:10.1155/2016/2853178.

    PMID: 27843654
  8. 8

    Monozygotic triplets with juvenile-onset autoimmunity and 18p microdeletion involving PTPRM.

    Herlin MK, Bernth Jensen JM, Andreasen L, et al.

    Frontiers in genetics 2024; (15()):1437566 doi:10.3389/fgene.2024.1437566.

    PMID: 39359478
  9. 9

    18p Deletion Syndrome Associated with Type 1 Diabetes and Hashimoto's Thyroiditis: A Case Report on Autoimmune Disorders and Genetic Factors.

    Oktay MA, Tunca Küçükali ET, Kılınç Uğurlu A, et al.

    Journal of clinical research in pediatric endocrinology 2025; doi:10.4274/jcrpe.galenos.2025.2025-6-5.

    PMID: 41194499

This page provides educational information about 18p deletion syndrome and is not a substitute for professional medical advice. Always consult your child's geneticist, endocrinologist, or pediatrician regarding their specific care plan.

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