Barriers to carrier testing for adult cystic fibrosis sibs: the importance of not knowing.

Early experience in centers offering population screening for cystic fibrosis (CF) has shown that few of the public are taking advantage of the offer [Miller, 1993: New Scientist 139:6]. There is similar low utilization among adult CF sibs [Fanos and Johnson, 1993: Am J Hum Genet 53:A51]. The purpose of this study was to identify factors motivating or interfering with the pursuit of carrier testing in adult CF sibs. Eighty-four adult CF sibs and their spouses, drawn from Children's Hospital, Oakland, CA, and Children's Hospital, Boston, MA, were interviewed for about an hour, and qualitative material was coded on various themes. Structural and psychological barriers to the transmission of genetic information were identified: 1) sibs encountered difficulty in obtaining information concerning availability of testing; 2) parental guilt and blame prevents parents from discussing genetic issues with the sib; 3) sibs rarely discuss testing with each other; 4) the CF patient or parent often has difficulty with the implications of the sib seeking carrier testing; 5) family and individual myths about carrier status influence the sib's decision to seek testing; 6) statistical odds have lost meaning in families where the rare has already occurred; 7) the sib fears loss of interpersonal desirability; and 8) carrier status can serve an important function in binding guilt. Remaining unaware of their carrier status may serve significant psychological functions for individuals at risk.