Genetic Counseling and Testing for FMR1 Gene Mutations: Practice Guidelines of the National Society of Genetic Counselors

Abstract

Fragile X syndrome (FXS) is one of several clinical disorders associated with mutations in the X-linked Fragile X Mental Retardation-1 (FMR1) gene. With evolving knowledge about the phenotypic consequences of FMR1 transcription and translation, sharp clinical distinctions between pre- and full mutations have become more fluid. The complexity of the issues surrounding genetic testing and management of FMR1-associated disorders has increased; and several aspects of genetic counseling for FMR1 mutations remain challenging, including risk assessment for intermediate alleles and the widely variable clinical prognosis for females with full mutations. FMR1 mutation testing is increasingly being off..