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PubMed This is a summary of 28 peer-reviewed journal articles Updated
Genetics · Proximal 18q Deletion Syndrome

Proximal 18q Deletion Syndrome Resource Guide

At a Glance

Proximal 18q Deletion Syndrome is a rare genetic condition caused by a missing piece in the middle of chromosome 18. Symptoms vary but often include developmental delays, low muscle tone, and structural heart defects. Care involves ongoing health screenings by a multidisciplinary medical team.

Welcome to the Proximal 18q Deletion Syndrome Resource Guide. Receiving a rare genetic diagnosis can be overwhelming, whether you are a parent seeking answers for your child or an adult who has just received a diagnosis. This guide is designed to translate complex medical information into clear, actionable steps, empowering you to advocate effectively with your medical team.

Proximal 18q Deletion Syndrome is a rare genetic condition in which a piece of the long arm (q) of chromosome 18 is missing. Because the deletion occurs in the middle of the chromosome (between 18q11.2 and 18q21.1), it is called an interstitial deletion [1]. This is distinct from the more common “distal” 18q deletions, which occur at the tip of the chromosome. The symptoms are highly variable depending on exactly which genes are missing, but they often include developmental delays, structural differences in the heart, and unique immune and endocrine needs [1][2].

How to Use This Guide

We have broken down the most critical information into five key sections. Please read through them at your own pace.

01

What is Proximal 18q Deletion Syndrome?

Learn the basics of Proximal 18q Deletion Syndrome (Proximal 18q-). Understand the causes, common symptoms, required baseline tests, and treatment options.

02

Genetics and the Microarray Report

Learn how to read your Proximal 18q deletion syndrome microarray report. Understand breakpoints, genome builds, and key missing genes like GATA6 and TCF4.

03

Developmental, Neurological, and Behavioral Expectations

Learn about the developmental, neurological, and behavioral expectations for proximal 18q deletion syndrome, including ADHD, hypotonia, and seizure risks.

04

Cardiac, Endocrine, and Immune System Management

Learn how proximal 18q deletion syndrome affects physical health. Understand cardiac risks, growth hormone deficiency, and immune system management options.

05

Building Your Care Team and Surveillance Schedule

Learn how to build a multidisciplinary care team for Proximal 18q Deletion Syndrome. Discover recommended screening schedules for heart, growth, and immune health.

Quick Glossary of Terms

  • De novo: A genetic change that occurred randomly and was not inherited from a parent.
  • Haploinsufficiency: When one copy of a gene is missing, and the single remaining copy is not enough to maintain normal function.
  • Hypotonia: Low muscle tone, often making limbs feel “floppy” and delaying physical milestones.
  • Conotruncal Defects: A type of structural heart defect affecting the major blood vessels that leave the heart.
  • Chromosomal Microarray (CMA): The gold-standard genetic test used to find small missing or extra pieces of chromosomes.

Common questions in this guide

What is the difference between proximal and distal 18q deletions?
A proximal deletion occurs in the middle of the chromosome's long arm, which is why it is also called an interstitial deletion. A distal deletion happens at the very tip of the chromosome. The missing genes and the resulting symptoms are different for each type.
What are the common symptoms of Proximal 18q Deletion Syndrome?
Symptoms can vary widely depending on the exact missing genes. Commonly reported signs include developmental delays, low muscle tone (hypotonia), and structural heart differences. Individuals may also experience growth hormone deficiencies, focal seizures, ADHD, or autism.
How is this genetic condition diagnosed?
The condition is typically diagnosed using a Chromosomal Microarray (CMA). This is a highly detailed genetic test that identifies small missing or extra pieces of chromosomes, including the specific genetic coordinates or breakpoints of the deletion.
Which medical specialists should be on our care team?
Because the syndrome affects multiple body systems, care requires a multidisciplinary approach. Your care team will likely include a geneticist, neurologist, cardiologist, endocrinologist, and an immunologist, along with a primary care coordinator.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Can you explain the difference between distal and proximal 18q deletions as it relates to my or my child's specific diagnosis?
  2. 2.What are the most critical next steps we should take in the first 30 days after receiving this diagnosis?
  3. 3.Who will serve as the primary coordinator or 'quarterback' for the multidisciplinary care team?

Questions For You

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References

References (2)
  1. 1

    Clinical delineation of 18q11-q12 microdeletion: Intellectual disability, speech and behavioral disorders, and conotruncal heart defects.

    Rojnueangnit K, Charalsawadi C, Thammachote W, et al.

    Molecular genetics & genomic medicine 2019; (7(9)):e896 doi:10.1002/mgg3.896.

    PMID: 31390163
  2. 2

    18q Deletion Syndrome Presenting with Late-Onset Combined Immunodeficiency.

    Hashiguchi S, Tomomasa D, Nishikawa T, et al.

    Journal of clinical immunology 2024; (44(7)):154 doi:10.1007/s10875-024-01751-4.

    PMID: 38896123

This guide provides educational information about Proximal 18q Deletion Syndrome and is not a substitute for professional medical advice. Always consult your geneticist and comprehensive healthcare team for medical decisions.

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