Fragile X syndrome

- a.k.a Martin-Bell syndrome
- X-linked recessive
- trinucleotide repeat disorder (in FMR 1 gene)   - genetic anticipation
- most common cause of inherited intellectual disability
- second most common known cause of mental retardation in males
- expansion of CGG on X-chromosome

• 6-55 : normal
• 55-230 : premutation carrier
• 230->1000 : disease state / full mutation

- features: elongated face, prognathism, macroorchidism, large low set floppy ear, short stature, hyperflexible joints, high arched palate, ADHD, autism