Prenatal screening for fragile x: carriers, controversies, and counseling.

In addition to causing developmental disability in future offspring, fragile X carrier status has important reproductive and mental health implications for the individual being tested. Accordingly, prenatal carrier screening and diagnosis using DNA-based molecular methods has become crucial in early detection, intervention, and family planning. Although the list of known genetic disorders is growing daily, controversy remains over who should be tested for fragile X. FMR1 gene mutations can result in inherited intellectual disability, infertility, and neurodegeneration syndromes that are encountered by clinicians in a variety of settings. Patients and clinicians are still largely unfamiliar with this disorder, its complicated inheritance, and its heterogeneous phenotype. Debate continues over who should be offered prenatal carrier screening. As more disease screening is offered, pretest counseling will become only more complex and clinicians will further struggle to balance the needs of the individual and allocation of public health resources.