Three main approaches have been used to prevent or reduce the incidence of<unk><unk><unk> : * Prenatal diagnosis. If both parents are identified as carriers, prenatal genetic testing can determine whether the fetus has inherited a defective gene copy from both parents. Chorionic villus sampling (CVS), the most common form of prenatal diagnosis, can be performed between 10 and 14 weeks of gestation. Amniocentesis is usually performed at 15–18 weeks. These procedures have risks of miscarriage of 1% or less. * Preimplantation genetic diagnosis. By retrieving the mother's eggs for in vitro fertilization, it is possible to test the embryo for the disorder prior to implantation. Healthy embryos are then selected and transferred into the mother's womb, while unhealthy embryos are discarded. In addition to<unk> , preimplantation genetic diagnosis has been used to prevent cystic fibrosis and sickle cell anemia among other genetic disorders. * Mate selection. In Orthodox Jewish circles, the organization Dor Yeshorim carries out an anonymous screening program so that carriers for<unk><unk><unk>  and other genetic disorders can avoid marrying each other.
Tay–Sachs disease
Sandhoff disease
Fox–Fordyce disease
Leigh syndrome
Bietti's crystalline dystrophy
Neuronal ceroid lipofuscinosis
Akureyri disease
Dejerine–Sottas disease