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Living with Mosaic trisomy 14

A rare chromosome condition with slow growth, developmental delay, intellectual disability, distinctive facial features, and heart differences.

Understanding Mosaic trisomy 14

Mosaic trisomy 14 is a rare chromosome condition in which some cells have three copies of chromosome 14 instead of two.

The extent and severity vary. Commonly reported signs include slow growth before birth, trouble gaining weight, developmental delay, intellectual disability, distinctive facial features, heart malformations, and other physical differences. Signs are seen during pregnancy or in the newborn period.

Signs & symptoms

Symptoms vary from person to person. GARD lists these among the most common:

  • Delays in reaching developmental milestones
  • Intellectual disability
  • Trouble gaining weight
  • Heart differences
  • Cleft palate and small jaw
  • Seizures

Not everyone has every symptom. GARD's list comes from the Human Phenotype Ontology.

Diagnosis

  1. Talk with your doctor

    Share the symptoms you've noticed, when they started and your family health history. Notes and photos can help.

  2. See a specialist

    Specialists who may be involved include genetic specialists.

  3. Ask which tests can help

    Your care team will decide which exams and tests can confirm the diagnosis.

Care & treatment

Care team
Genetic specialists (geneticists)
Expert care
Ask about multidisciplinary care centers for rare conditions
Treatment
GARD doesn't list specific treatments for this condition. Your care team will tailor care to your symptoms.
Research
Clinical trials and observational studies may be options. See the research section below.

General information, not medical advice. Your care team makes the decisions.

Everyday life

Living with a rare condition is easier with support.

  • Connect with Chromosome Disorder Outreach
  • Keep notes on symptoms, changes and questions for appointments
  • Ask about patient registries that help research
  • Look into financial aid and travel resources for care visits
Bring these questions to your next doctor visit
Which tests confirm the mosaic pattern?
Which specialists should check the heart and development?
What feeding and growth support is available?

Quick facts

Symptoms usually startduring Pregnancy and as a Newborn

GARD says this condition is most often caused by an error in cell division in the egg or sperm cell before conception, or in fetal cells after fertilization.

Genetic

Also known as: mosaic trisomy 14 syndrome; mosaic trisomy chromosome 14; mosaic trisomy type 14; trisomy 14 mosaicism

Patient organizations

Broader rare-disease groups

Source: NIH GARD · Mosaic trisomy 14GARD ID 1327 · GARD page updated September 2026 · Plain-language summary by Know Rare; editorial review pending. General information, not medical advice.

You are more than your diagnosis

Perspectives from people navigating life with Mosaic trisomy 14.

Explore the Mosaic trisomy 14 blog

Explore research for Mosaic trisomy 14

Explore actively recruiting Mosaic trisomy 14 studies with HealthSpark.

HealthSpark

Find actively recruiting studies for Mosaic trisomy 14 with HealthSpark. Share your city to explore research near you.

  • Recruiting studies from ClinicalTrials.gov
  • Share your city to look for research near you
  • Eligibility is confirmed by the study team

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Powered by HealthSpark, our AI chat helper · Study information from ClinicalTrials.gov · Eligibility is confirmed by the study team.

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