Frequency of holoprosencephaly in the International Clearinghouse Birth Defects Surveillance Systems: searching for population variations.
BACKGROUND
Holoprosencephaly (HPE) is a developmental field defect of the brain that results in incomplete separation of the cerebral hemispheres that includes less severe phenotypes, such as arhinencephaly and single median maxillary central incisor. Information on the epidemiology of HPE is limited, both because few population-based studies have been reported, and because small studies must observe a greater number of years in order to accumulate sufficient numbers of births for a reliable estimate.


METHODS
We collected data from 2000 through 2004 from 24 of the 46 Birth Defects Registry Members of the International Clearinghouse for Birth Defects Surveillance and Research. This study is based on more than 7 million births in various areas from North and South America, Europe, and Australia.


RESULTS
A total of 963 HPE cases were registered, yielding an overall prevalence of 1.31 per 10,000 births. Because the estimate was heterogeneous, possible causes of variations among populations were analyzed: random variation, under-reporting and over-reporting bias, variation in proportion of termination of pregnancies among all registered cases and real differences among populations.


CONCLUSIONS
The data do not suggest large differences in total prevalence of HPE among the studied populations that would be useful to generate etiological hypotheses.
Leoncini
Emanuele
E
Centre of the International Clearinghouse for Birth Defects Surveillance and Research, Roma, Italy.
Baranello
Giovanni
G
Orioli
Iêda M
IM
Annerén
Göran
G
Bakker
Marian
M
Bianchi
Fabrizio
F
Bower
Carol
C
Canfield
Mark A
MA
Castilla
Eduardo E
EE
Cocchi
Guido
G
Correa
Adolfo
A
De Vigan
Catherine
C
Doray
Berenice
B
Feldkamp
Marcia L
ML
Gatt
Miriam
M
Irgens
Lorentz M
LM
Lowry
R Brian
RB
Maraschini
Alice
A
Mc Donnell
Robert
R
Morgan
Margery
M
Mutchinick
Osvaldo
O
Poetzsch
Simone
S
Riley
Merilyn
M
Ritvanen
Annukka
A
Gnansia
Elisabeth Robert
ER
Scarano
Gioacchino
G
Sipek
Antonin
A
Tenconi
Romano
R
Mastroiacovo
Pierpaolo
P
D000569:Americas; D001315:Australia; D000013:Congenital Abnormalities / Q000453:epidemiology*; D005060:Europe; D005260:Female; D016142:Holoprosencephaly / Q000453:epidemiology*; D006801:Humans; D007391:International Cooperation; D050498:Live Birth / Q000453:epidemiology; D011159:Population Surveillance / Q000379:methods; D011247:Pregnancy; D015995:Prevalence; D012042:Registries; D050497:Stillbirth / Q000453:epidemiology