fragile X syndrome
Findings
No curated finding names fragile X syndrome yet. Everything below is reference data from Mondo, HPO and GenCC, not evidence about what affects it.
Definition
A genetic syndrome caused by mutations in the FMR1 gene which is responsible for the expression of the fragile X mental retardation 1 protein. This protein participates in neural development. This syndrome is manifested with mental, emotional, behavioral, physical, and learning disabilities.
Definition from the Mondo Disease Ontology (MONDO:0010383), read 2026-09-29. CC BY 4.0.
- Onset and course
- Childhood onset
HPO, annotations 2026-09-02
Features
38 features
What the disease is reported to present with, and how often among people who have it — never how often a feature means the disease. HPO, annotations 2026-09-02.
- Moderate intellectual disabilityHPOHP:0002342
- 13 of 13 reported patients
- Very frequent (80% to 99% of cases)
- Abnormal speech patternHPOHP:0002167
- Very frequent (80% to 99% of cases)
- Chronic otitis mediaHPOHP:0000389
- Very frequent (80% to 99% of cases)
- Folate-dependent fragile site at Xq28HPOHP:0003564
- Very frequent (80% to 99% of cases)
- Joint hypermobilityHPOHP:0001382
- Very frequent (80% to 99% of cases)
- MacroorchidismHPOHP:0000053
- Very frequent (80% to 99% of cases)
Show the remaining 26
- Frontal bossingHPOHP:0002007
- Frequent (30% to 79% of cases)
- Gastroesophageal refluxHPOHP:0002020
- Frequent (30% to 79% of cases)
- HypotoniaHPOHP:0001252
- Frequent (30% to 79% of cases)
- Large foreheadHPOHP:0002003
- 3 of 13 reported patients
- Frequent (30% to 79% of cases)
- Long faceHPOHP:0000276
- 5 of 13 reported patients
- Frequent (30% to 79% of cases)
- MacrocephalyHPOHP:0000256
Genes
1 gene
Germline variants in the gene encoding each protein, as classified by GenCC submitters, each in their own words. Limited, disputed and refuted submissions are listed too.
- FMR1HGNC:3775
- Definitive · Ambry Genetics · X-linked · 2017
- Definitive · ClinGen · X-linked · 2019
- Definitive · Myriad Women's Health · X-linked · 2018
- Definitive · G2P · X-linked · 2016
- Definitive · Natera · X-linked · 2022
- Strong · Labcorp Genetics (formerly Invitae) · X-linked · 2023
- Strong · PanelApp Australia · X-linked · 2025
- Supportive · Orphanet · X-linked · 2021
Where it sits
- A kind of
Other names
7 names
Resolves to: fragile X syndrome
- Also called
- fragile X intellectual disability syndromeFragile X syndrome, X-linked dominantFraX syndromeFRAXA syndromeFXSmarker X syndromeMartin-Bell syndrome