Does theFMR1 gene affect IVF success?

Area of Science:

• Genetics
• Reproductive Medicine
• In Vitro Fertilization (IVF)

Background:

• Fragile X gene (FMR1) CGG trinucleotide repeat expansions are linked to Fragile X syndrome and primary ovarian insufficiency.
• The influence of FMR1 CGG repeat length on the success of fertility treatments, particularly IVF, remains unclear.

Purpose of the Study:

• To review the effect of FMR1 CGG repeat lengths on in vitro fertilization (IVF) outcomes following ovarian stimulation.
• To synthesize existing research on the association between FMR1 CGG repeat variations and IVF success rates.

Main Methods:

• A comprehensive literature search was conducted on PubMed for studies published between 2002 and December 2017.
• Studies focused on IVF-related outcomes stratified by FMR1 trinucleotide repeat length were included.
• Meta-analysis was performed to assess associations within normal repeat length subcategories.

Main Results:

• Women with normal (<45 CGG) or intermediate (45-54 CGG) FMR1 CGG repeat lengths showed minimal impact on IVF outcomes, including pregnancy rates.
• One study indicated lower oocyte yields in women with shorter CGG repeats and normal ovarian reserve undergoing IVF.
• Meta-analysis found no significant association between normal FMR1 CGG repeat lengths (<45 CGG) and IVF pregnancy rates (OR 1.0, 95% CI 0.87-1.15).
• Premutation carriers (55-200 CGG) may have reduced IVF success, specifically lower oocyte yield, though findings are inconsistent.

Conclusions:

• FMR1 CGG repeat length appears to have a limited effect on overall IVF success and pregnancy rates for most women.
• Premutation carriers might experience diminished oocyte yield in IVF, suggesting potential clinical implications.
• Consideration of clinical and psychological counseling, alongside preimplantation genetic testing, is recommended for patients with FMR1 repeat expansions.