Prenatal diagnosis of alpha-thalassemia-1 (SEA type) by chorionic villus sampling.

Chanprapaph, Pharuhas; Tongsong, Theera; Wanapirak, Chanane; Sirichotiyakul, Supattra; Sanguansermsri, Torpong

Prenatal diagnosis of alpha-thalassemia-1 (SEA type) by chorionic villus sampling.

Date

2002-10-28

Authors

Chanprapaph, Pharuhas

Tongsong, Theera

Wanapirak, Chanane

Sirichotiyakul, Supattra

Sanguansermsri, Torpong

Abstract

OBJECTIVE: To describe the experience of prenatal diagnosis for Hb Bart's disease, by chorionic villus sampling (CVS) with DNA analysis. DESIGN: Descriptive study SETTINGS: Department of Obstetrics and Gynecology, Faculty of Medicine, Chiang Mai University. SUBJECTS: 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. MATERIAL AND METHOD: 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. MAIN OUTCOME MEASURES: 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. CONCLUSION: This preliminary experience suggests that CVS is an effective method for early prenatal diagnosis of fetal Hb Bart's.

Description

Chotmaihet Thangphaet.

Citation

Chanprapaph P, Tongsong T, Wanapirak C, Sirichotiyakul S, Sanguansermsri T. Prenatal diagnosis of alpha-thalassemia-1 (SEA type) by chorionic villus sampling. Journal of the Medical Association of Thailand. 2002 Oct; 85(10): 1049-53