Recurrence risks in offspring of adults with major heart defects: results from first cohort of British collaborative study.
BACKGROUND
Congenital heart defects are generally assumed to have a multifactorial aetiology. We have tested this hypothesis by studying adults with heart defects and their families.


METHODS
We identified 1094 patients who survived surgery for major cardiac defects before 1970. We chose individuals with disturbance of situs or segmental connection, with atrioventricular septal defect or with tetralogy of Fallot. After exclusion and non-participation, 727 individuals were traced. Each was visited by an investigator and completed a detailed questionnaire. If possible, all "normal" offspring were examined by a paediatric cardiologist.


RESULTS
The 727 individuals had 393 live offspring. There were 71 miscarriages and five terminated pregnancies. Overall, we found recurrent heart defects in 16 liveborn offspring--a recurrence risk of 4.1%. This result differed significantly from sibling risk (2.1%; p=0.021). More congenital heart defects occurred in the offspring of affected women than in those of affected men (p=0.047); when all malformations (cardiac and non-cardiac) in the offspring were taken into account the excess was more significant (p=0.032). We found an excess of miscarriages in the offspring of affected women (p=0.001). In tetralogy of Fallot, heart defects occurred in seven (3.1%) of 223 offspring, 12 (2.2%) of 539 siblings, five (0.3%) of 1575 second-degree relatives, and eight (0.3%) of 2728 third-degree relatives.


CONCLUSIONS
Our findings do not support a polygenic basis for all heart defects. Atrioventricular septal defect seems to be a single-gene defect and tetralogy of Fallot a polygenic disorder with a small number of interacting genes. Our data suggest that isolated transposition of the great arteries is a sporadic defect.
Burn
J
J
Department of Human Genetics, University of Newcastle upon Tyne, UK.
Brennan
P
P
Little
J
J
Holloway
S
S
Coffey
R
R
Somerville
J
J
Dennis
N R
NR
Allan
L
L
Arnold
R
R
Deanfield
J E
JE
Godman
M
M
Houston
A
A
Keeton
B
B
Oakley
C
C
Scott
O
O
Silove
E
E
Wilkinson
J
J
Pembrey
M
M
Hunter
A S
AS
D000328:Adult; D002648:Child; D016241:Child of Impaired Parents; D015331:Cohort Studies; D005260:Female; D006330:Heart Defects, Congenital / Q000235:genetics*; D006345:Heart Septal Defects, Ventricular / Q000235:genetics; D006801:Humans; D008297:Male; D011446:Prospective Studies; D012306:Risk; D012737:Sex Factors; D011795:Surveys and Questionnaires; D013771:Tetralogy of Fallot / Q000235:genetics; D006113:United Kingdom