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Living with Intellectual disability, X-linked 1

An X-linked genetic condition (IQSEC2-related) with severe intellectual disability and behavior differences.

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Understanding Intellectual disability, X-linked 1

Intellectual disability, X-linked 1 is an X-linked dominant condition caused by mutations in the IQSEC2 gene, with impaired intellectual functioning and behavior differences.

It starts in the newborn period or infancy. People often have delayed development, low muscle tone, and some lose milestones they had gained.

Signs & symptoms

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

  • Severe intellectual disability
  • Global developmental delay
  • Loss of developmental skills (regression)
  • Low muscle tone
  • Behavior differences
  • Reduced social responsiveness

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 brain and nervous system specialists, genetic specialists and seizure and epilepsy specialists.

  3. Consider genetic testing

    Changes in IQSEC2 are linked to this condition. Genetic testing and counseling can help confirm a diagnosis and explain what it means for your family.

  4. Connect with expert centers

    Epilepsy Foundation may keep lists of experts for this condition.

Care & treatment

Care team
Brain and nervous system specialists (neurologists); Genetic specialists (geneticists); Seizure and epilepsy specialists (epileptologist)
Expert care
Expert lists: Epilepsy Foundation
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 Simons Searchlight and other patient organizations
  • 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
Can genetic testing for the IQSEC2 gene confirm the diagnosis?
What does X-linked dominant inheritance mean for our family?
Which therapies help with development and behavior?

Quick facts

Symptoms usually startNewborn and as an Infant
InheritanceX-Linked
GenesIQSEC2

Mutations in the IQSEC2 gene on chromosome Xp11 cause this condition. It is inherited in an X-linked dominant pattern.

GeneticNeurological

Also known as: atkin flaitz patil smith syndrome; intellectual developmental disorder, x-linked 1; intellectual developmental disorder, x-linked 1, x-linked dominant; iqsec2 (iq motif and sec7 domain 2) related syndromic intellectual disability; iqsec2-related disorder; iqsec2-related syndromic intellectual disability

Patient organizations

Source: NIH GARD · Intellectual disability, X-linked 1GARD ID 22699 · 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 Intellectual disability, X-linked 1.

Explore the Intellectual disability, X-linked 1 blog
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Embrace the Ask: How to Seek The Support You Need

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Explore research for Intellectual disability, X-linked 1

Explore actively recruiting Intellectual disability, X-linked 1 studies with HealthSpark.

HealthSpark

Find actively recruiting studies for Intellectual disability, X-linked 1 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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