X fragile

AP Pediatrics

Fragile X Syndrome

It is the most common hereditary cause of intellectual disability and the most common monogenic cause of Autism Spectrum Disorder (ASD).

Men

More severe affectation. Prevalence 1:4000.

Women

They usually have mild involvement or are carriers. Prevalence 1:8000.

Etiology

Trinucleotide repeat expansion CGG in the gene FMR1 (Xq27.3). The complete mutation (>200 repeats) causes methylation of the gene and the absence of the FMRP protein, crucial for synaptic development.

Red Flags of Development

Select the signs observed in the consultation to record the patient's profile.

Signs detected: 0 / 5

Rapid Assessment (AP)

Answer Yes or No to calculate the index of clinical suspicion in your patient.

Physical Phenotype

1. Does he have prominent, large or handle ears?

2. Long face with a wide forehead or prominent jaw?

3. Macroorchidism?

(Testicular volume >25ml. Evident especially peripuberty/postpuberty)

4. Joint laxity (hyperextensibility) or flat feet?

Milestones and Background

5. Intellectual disability or global developmental delay?

6. Traits compatible with ASD?

(flapping, poor eye contact, disturbance in social interaction)

7. Suspicious family history?

(Intellectual disability of unknown cause, Premature Ovarian Failure, or Tremor/Ataxia Syndrome associated with Fragile X in grandparents)