Active cascade testing for carriers of cystic fibrosis gene.
OBJECTIVE
To examine the acceptability, practicability, efficiency, and application of active screening for carriers of the cystic fibrosis gene in the extended families of those in whom the disease is present (Cascade screening).


METHODS
Paediatricians and physicians provide details of their affected patients, pedigrees are drawn up, and relatives offered tests after initial contact by the affected nuclear families. Affected patients are genotyped in a laboratory with a special interest in the genetics of cystic fibrosis.


METHODS
North Western health region.


METHODS
Relatives and partners of 607 people with cystic fibrosis.


METHODS
Genetic counselling by letter for people found to be carriers; formal genetic counselling and when indicated arrangements for prenatal diagnosis for couples discovered to be carriers.


METHODS
Number of carrier couples detected; action in pregnancy of detected carrier couples; extent of the uptake of screening by relatives.


RESULTS
Of 1563 relatives or partners tested, 15 carrier couples were detected; of nine pregnancies undertaken by these 15, eight had prenatal tests and three terminated pregnancies. An average of 16 people per family have come forward for testing so far.


CONCLUSIONS
Cascade screening for carriers of cystic fibrosis is well accepted by relatives, especially on the mother's side of the family; it is 10 times more efficient in detecting carrier couples than unfocused screening. Detected carrier couples make practical use of the information in pregnancy. Active cascade screening for carriers is effective in cystic fibrosis and widespread application is recommended. These principles could be applied to other recessive disorders.
Regional Genetics Service, Royal Manchester Children's Hospital, Pendlebury.
M
M
Super
M J
MJ
Schwarz
G
G
Malone
T
T
Roberts
A
A
Haworth
G
G
Dermody
D003550:Cystic Fibrosis / Q000175:diagnosis / Q000235:genetics*; D004252:DNA Mutational Analysis; D005260:Female; D005315:Fetal Diseases / Q000175:diagnosis / Q000235:genetics; D006580:Genetic Carrier Screening; D005817:Genetic Counseling; D005820:Genetic Testing / Q000379:methods; D006579:Heterozygote; D006801:Humans; D009154:Mutation; D010342:Patient Acceptance of Health Care; D010375:Pedigree; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000379:methods; D018570:Risk Assessment