Objectives: Phacomatoses are a group of neuro-oculo-cutaneous syndromes/ neurocutaneous disorders, involving structures arising from the embryonic ectoderm. Most of phacomatoses including the most common ones:, neurofibromatosis type I and type II (NF1, NF2) and tuberosclerosis complex (TSC), are autosomal dominant genetic disorders with full penetrance and variable expression. As no effective treatment exists, the only way to prevent the disease, is by prenatal genetic diagnosis (either chorionic villus sampling-CVS or amniocentesis-AC) and termination of pregnancy or performing preimplantation genetic testing (PGT). As the risk for an affected offspring is 50% in every pregnancy of an affected parent, prenatal, and preimplantation testing are of great importance. However, those procedures are associated with technical and ethical concerns. This chapter shortly reviews the common phacomatoses emphasizes their genetics and inheritance. We will review the common methods for prenatal and preimplantation diagnoses and discuss its use in common phacomatoses.
Conclusion: Phacomatoses are common autosomal dominant genetic conditions with variable expression. Ante-natal genetic diagnosis is an appropriate approach for family planning in individuals affected by phacomatosis or parents of an affected child.
Keywords: Amniocentesis; Chorionic villi sampling; Germline gene editing; Neurofibromatosis type 1; Neurofibromatosis type 2; Phacomatoses; Preimplantation genetic testing; Prenatal genetic counseling; Prenatal genetic diagnosis; Tuberosclerosis complex.