Prenatal diagnosis of alpha-thalassemia-1 (SEA type) by chorionic villus sampling.
OBJECTIVE
To describe the experience of prenatal diagnosis for Hb Bart's disease, by chorionic villus sampling (CVS) with DNA analysis.


METHODS
Descriptive study


METHODS
Department of Obstetrics and Gynecology, Faculty of Medicine, Chiang Mai University.


METHODS
Sixteen high risk pregnancies at risk of Hb Bart's disease who were eligible for CVS criteria between 1 January, 1999 and May 31, 2000.


METHODS
Fetal villi were obtained by either transcervical (TC) or transabdominal (TA) CVS route to extract DNA and detect for alpha-thal-1 gene deletion (SEA type) with modified Chang's method. The CVS results were confirmed by either serial ultrasound or cordocentesis or diagnosis after pregnancy termination.


METHODS
The efficacy, safety and pregnancy outcomes.


RESULTS
CVS was successfully done in all of 16 cases (5 with TC and 11 with TA), The mean gestational age was 13.25 +/- 2.9 weeks. The procedure time for TA was shorter than that of TC (4.64 +/- 5.4 vs 10.4 +/- 11.3 min). The CVS result showed as follows: 3 normal fetuses, 7 alpha-thal-1 carriers, 4 fetal Hb Bart's, 1 misdiagnosis and 1 failure to diagnosis due to technical error. The sensitivity and specificity were 100 per cent (4/4) and 90.91 per cent (10/11), respectively. One case of Hb Bart's misdiagnosis and one failure case were later confirmed for alpha-thal-1 trait and alpha-thal-1/ Hb E trait by cordocentesis, respectively. The pregnancy outcomes included 11 livebirths, 4 terminated cases and 1 fetal loss of continuing pregnancies. No serious complications occurred.


CONCLUSIONS
This preliminary experience suggests that CVS is an effective method for early prenatal diagnosis of fetal Hb Bart's.
Chanprapaph
Pharuhas
P
Department of Obstetrics and Gynecology, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand.
Tongsong
Theera
T
Wanapirak
Chanane
C
Sirichotiyakul
Supattra
S
Sanguansermsri
Torpong
T
D015193:Chorionic Villi Sampling; D005260:Female; D005315:Fetal Diseases / Q000175:diagnosis; D006801:Humans; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D011256:Pregnancy Outcome; D018566:Pregnancy, High-Risk; D017085:alpha-Thalassemia / Q000175:diagnosis* / Q000235:genetics