Overview
1p21.3 microdeletion syndrome is a rare genetic condition caused by a small missing piece (deletion) of chromosome 1 at a specific location called 1p21.3. This syndrome is sometimes also referred to as chromosome 1p21.3 deletion syndrome. Because this region of the chromosome contains genes important for brain development and function, the condition primarily affects learning, speech, and behavior. People with this syndrome typically experience intellectual disability that ranges from mild to moderate, along with significant delays in speech and language development. Many children are late to reach developmental milestones such as sitting, walking, and talking. Behavioral challenges, including features of autism spectrum disorder, are commonly reported. Some individuals may also have distinctive facial features, though these can be subtle and vary from person to person. There is currently no cure for 1p21.3 microdeletion syndrome. Treatment focuses on managing symptoms and supporting development through early intervention programs, speech therapy, occupational therapy, and behavioral support. With appropriate therapies and educational accommodations, many individuals can make meaningful progress in their development and quality of life. The DPYD gene and other genes in this region are thought to play a role in the features seen in this condition.
Also known as:
Key symptoms:
Intellectual disability (mild to moderate)Delayed speech and language developmentDelayed motor milestones like walkingBehavioral difficultiesFeatures of autism spectrum disorderLow muscle tone (feeling floppy as a baby)Subtle distinctive facial featuresLearning difficulties in schoolAttention problemsAnxiety or emotional challengesFeeding difficulties in infancyShort stature in some casesSeizures in some individuals
Clinical phenotype terms (25)— hover any for plain English
Variable
Can be inherited in different ways depending on the underlying gene
Infantile
Begins in infancy, roughly 1 month to 2 years old
Treatments
No FDA-approved treatments are currently listed for 1p21.3 microdeletion syndrome.
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Specialists
View all specialists →No specialists are currently listed for 1p21.3 microdeletion syndrome.
Treatment Centers
8 centersBaylor College of Medicine Rare Disease Center ↗
Baylor College of Medicine
📍 Houston, TX
🏥 NORDStanford Medicine Rare Disease Center ↗
Stanford Medicine
📍 Stanford, CA
🔬 UDNNIH Clinical Center Undiagnosed Diseases Program ↗
National Institutes of Health
📍 Bethesda, MD
🔬 UDNUCLA UDN Clinical Site ↗
UCLA Health
📍 Los Angeles, CA
🔬 UDNBaylor College of Medicine UDN Clinical Site ↗
Baylor College of Medicine
📍 Houston, TX
🔬 UDNHarvard/MGH UDN Clinical Site ↗
Massachusetts General Hospital
📍 Boston, MA
🏥 NORDMayo Clinic Center for Individualized Medicine ↗
Mayo Clinic
📍 Rochester, MN
👤 Mayo Clinic Center for Individualized Medicine
🏥 NORDUCLA Rare Disease Day Program ↗
UCLA Health
📍 Los Angeles, CA
Travel Grants
No travel grants are currently matched to 1p21.3 microdeletion syndrome.
Community
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Caregiver Resources
NORD Caregiver Resources
Support, advocacy, and financial assistance for caregivers of rare disease patients.
Mental Health Support
Rare disease caregiving can be isolating. Connect with counseling and peer support.
Family & Caregiver Grants
Financial assistance programs specifically for caregivers of rare disease patients.
Social Security Disability
Learn how rare disease patients may qualify for SSDI/SSI benefits.
Questions for your doctor
Bring these to your next appointment
- Q1.What is the exact size of my child's deletion, and which genes are affected?,Was this deletion inherited or did it happen for the first time in my child?,What therapies should we start right away, and how often?,Should my child be screened for seizures or other medical complications?,What educational supports and accommodations should we request at school?,Are there any clinical studies or research programs we could participate in?,What is the chance of this happening again in a future pregnancy?
Common questions about 1p21.3 microdeletion syndrome
What is 1p21.3 microdeletion syndrome?
1p21.3 microdeletion syndrome is a rare genetic condition caused by a small missing piece (deletion) of chromosome 1 at a specific location called 1p21.3. This syndrome is sometimes also referred to as chromosome 1p21.3 deletion syndrome. Because this region of the chromosome contains genes important for brain development and function, the condition primarily affects learning, speech, and behavior. People with this syndrome typically experience intellectual disability that ranges from mild to moderate, along with significant delays in speech and language development. Many children are late to
At what age does 1p21.3 microdeletion syndrome typically begin?
Typical onset of 1p21.3 microdeletion syndrome is infantile. Age of onset can vary across affected individuals.