Three generations of matrilineal excess of birth defects in Irish families with neural tube defects.
BACKGROUND
Neural tube defects (NTDs) and birth defects overall are more likely to occur among maternal compared to paternal relatives in two generations (uncles/aunts and first cousins) of Irish families where an individual has been born with an NTD.


OBJECTIVE
The aim of this study was to determine if the matrilineal excess persisted into the third generation.


METHODS
First cousins were interviewed about their pregnancy outcomes and their offsprings' health.


RESULTS
Maternal first cousins once removed (FCOR) were more likely to have birth defects than paternal FCOR: 6.7 versus 3.5% (adjusted odds ratio 1.49, 95% CI 0.57, 3.89). No NTDs occurred. Folic acid supplementation significantly reduced the risk of birth defects (P = 0.04).


CONCLUSIONS
This study demonstrates an excess of birth defects among maternal relatives in three consecutive generations of NTD families, and supports the hypothesis that an underlying mechanism links distant maternal relatives in at least some NTD families.
Boyne Research Institute, Duke House, Duke Street, Drogheda, Ireland. jbyrne@boyneresearch.ie
J
J
Byrne
D000013:Congenital Abnormalities / Q000235:genetics*; D005190:Family; D005260:Female; D006801:Humans; D008297:Male; D009436:Neural Tube Defects / Q000235:genetics*; D011247:Pregnancy; D011256:Pregnancy Outcome