Congenital heart disease in a population of dizygotic twins: an echocardiographic study.
BACKGROUND
Congenital heart disease (CHD) is the most common malformation in the fetal and neonatal period but little is known about its cause. The distribution analysis of CHD in dizygotic twins could provide a useful tool to evaluate the role of genetic and environmental factors in the development of CHD. Dizygotic twins are siblings with different genes, growing together in the same womb.


OBJECTIVE
To investigate the occurrence of CHD in a large sample of dizygotic twins of nonconsanguineous healthy parents, comparing the data from non-twin patients.


METHODS
From January 1999 to December 2002, we enrolled 1743 CHD patients with, at least 1 sibling, and 66 pairs of dizygotic twins, referred to our tertiary center. The diagnosis of CHD was based on clinical and echocardiographic evaluation.


RESULTS
Considering only the sibling nearest in age for each non-twin patient the recurrence was 67/1743 (3.8%). Among these 67 patients, 35 (52.2%) had a sibling with the same or similar CHD. Conversely, considering all 1886 siblings, recurrence of CHD in the non-twin group was 70/1743 (4%). Of the 70 patients, 36 (36/70, 51.4%) had a sibling with the same suspected pathogenic mechanism of CHD. In 9/66 pairs of twins (13.6%), both siblings had a CHD. In the nine pairs of twins in whom both siblings had a CHD, the percentage of concordance (based on the suspected pathogenic mechanism) for CHD was 100% (p<0.05).


CONCLUSIONS
Our findings suggest that the higher recurrence and concordance of CHD found in dizygotic twins could depend on some poorly identified environmental risk during the pregnancy.
Pediatric Cardiology, Second University of Naples, Monaldi Hospital, Naples, Italy. ss.caputo@libero.it
Salvatore
S
Caputo
Maria Giovanna
MG
Russo
Giovanbattista
G
Capozzi
Carmela
C
Morelli
Paola
P
Argiento
Giovanni
G
Di Salvo
Berardo
B
Sarubbi
Giuseppe
G
Santoro
Giuseppe
G
Pacileo
Raffaele
R
Calabrò
D000328:Adult; D004200:Diseases in Twins / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000209:etiology; D018618:Echocardiography, Doppler, Color; D005260:Female; D020022:Genetic Predisposition to Disease; D006330:Heart Defects, Congenital / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000209:etiology; D006801:Humans; D015994:Incidence; D007231:Infant, Newborn; D007558:Italy / Q000453:epidemiology; D008297:Male; D018811:Maternal Exposure / Q000009:adverse effects; D011247:Pregnancy; D012008:Recurrence; D012189:Retrospective Studies; D012307:Risk Factors; D035781:Siblings; D014429:Twins, Dizygotic; D014741:Video Recording