Screening for fragile X syndrome: a model for genetic disorders?

BMJ 1997;315:1174-1175 (8 November)

Editorials

Screening for fragile X syndrome: a model for genetic disorders?

The merits of screening should be considered separately for each disorder

The fragile X syndrome is often cited as the commonest inheritedcause of mental handicap. It was described after the findingthat a fragile site at the distal end of the X chromosome wasassociated with mental handicap. The X linked inheritance patternis atypical; female carriers may show some features, and malesmay also occasionally be asymptomatic carriers. Fragile X syndromewas the first of an increasing number of neurological genetic conditionsin which a dynamic mutation of a triplet repeat was identified,where instability between generations explained the unusualinheritance pattern.¹ The documentation of the molecular pathologyin fragile X allowed confirmation of carrier status in bothmale and female family members. The growth in understandingof the condition led to early calls for screening,² proposedboth to implement early therapy and to reduce the birth prevalence.