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.
Centre of the International Clearinghouse for Birth Defects Surveillance and Research, Roma, Italy.
Emanuele
E
Leoncini
Giovanni
G
Baranello
Iêda M
IM
Orioli
Göran
G
Annerén
Marian
M
Bakker
Fabrizio
F
Bianchi
Carol
C
Bower
Mark A
MA
Canfield
Eduardo E
EE
Castilla
Guido
G
Cocchi
Adolfo
A
Correa
Catherine
C
De Vigan
Berenice
B
Doray
Marcia L
ML
Feldkamp
Miriam
M
Gatt
Lorentz M
LM
Irgens
R Brian
RB
Lowry
Alice
A
Maraschini
Robert
R
Mc Donnell
Margery
M
Morgan
Osvaldo
O
Mutchinick
Simone
S
Poetzsch
Merilyn
M
Riley
Annukka
A
Ritvanen
Elisabeth Robert
ER
Gnansia
Gioacchino
G
Scarano
Antonin
A
Sipek
Romano
R
Tenconi
Pierpaolo
P
Mastroiacovo
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