A premutation carrier is an individual, male or female, who has between 55-200 CGG repeats in the Fragile X (FMR1) gene. The full mutation is defined as over 200 CGG repeats. People who have other fragile X-related conditions (not FXS) have changes in their FMR1 gene but usually still make some FMRP. Carriers of a premutation are at risk to develop the following FXS related conditions:
FXPOI is a condition in which the ovaries are not functioning at full capacity in an FMR1 female premutation carrier. Common symptoms include absent or irregular periods, symptoms of menopause such as hot flashes, etc, early menopause and infertility. Women who have a premutation in their FMR1 gene are at higher risk for having children who have FXS.
FXTAS is an “adult onset” neurodegenerative disorder, occurring more commonly in males than females. It is a disorder that can cause tremors and problems with walking, balance (also called ataxia), memory, mood disorders and eventual congnitive decline among older adults.
Some people with a premutation may have noticeable symptoms, and others may not.