[Fragile X syndrome: premature ovarian failure. Preimplantation and preconception genetic diagnosis].
Although it is generally accepted that women who are carriers of the premutation of the fragile X syndrome (FXS) show no pathological clinical features, several studies have shown that they have a higher incidence of premature failure of their ovaries (early menopause) than the general population. However, when women who are carriers of the complete mutation are studied, no relation is seen between the two conditions. All women who are carriers of the premutation of the FMR1 gene should be informed that they have a greater possibility than the general population (10-15 times) of having an early menopause. Pre-implantation genetic diagnosis (PGD) is a technique used in diagnosis, based on genetic analysis of an embryo obtained by in vitro fertilization (IVF) and subsequently transferred to genetically healthy viable embryos. Preconception genetic diagnosis is based on the genetic study of an ovule before fertilization and subsequent IVF of healthy ovules. The methodology is similar in both cases. Genetic study of FXS is especially difficult because of the large number of CGG repetitions in affected. Often indirect diagnosis has to be made. Both diagnoses have a series of evident advantages over prenatal diagnosis. There is no pregnancy present so the stress and emotional trauma of VIP (voluntary interruption of pregnancy) is avoided. However, it should be pointed out that there are technical drawbacks regarding genetic analysis and the need to resort to IVF in fertile couples.
Milà
M
M
Servicio de Genética, Hospital Clínico, Barcelona, Spain. mmila@clinic.ub.es
Mallolas
J
J
D020732:Cytogenetic Analysis; D005260:Female; D005307:Fertilization in Vitro; D005600:Fragile X Syndrome / Q000175:diagnosis*; D005820:Genetic Testing; D006579:Heterozygote; D006801:Humans; D008594:Menopause, Premature; D016742:Preconception Care; D011247:Pregnancy; D019836:Preimplantation Diagnosis; D016649:Primary Ovarian Insufficiency; D012307:Risk Factors; D018911:Trinucleotide Repeats