A family at risk of congenital adrenal hyperplasia: a molecular approach for prenatal diagnosis.

The molecular method for prenatal diagnosis in the first trimester was carried out on the second and third pregnancies of a family at risk of congenital adrenal hyperplasia (CAH). The first child, an 8-year-old daughter, was affected. The molecular and cytogenetic prenatal diagnosis on the second pregnancy revealed that the fetus which was a female had been affected. The pregnancy was then terminated. The couple presented with the third pregnancy at 8 weeks' gestation. The same approach revealed that the fetus, a male, was affected. The couple opted for continuation of pregnancy which was on-going at the time of the manuscript preparation. To our knowledge, this is the first family in Thailand who had molecular approach for prenatal diagnosis of CAH. This approach allows early information about the fetal status of the disease and, together with the result of fetal gender, will help early decision making in pregnancy management.

Charts of Thai fetal biometries: 2. Biparietal diameter.

A cross-sectional study was conducted in order to construct a new reference chart for Thai fetal biparietal diameter (BPD). A total of 621 normal pregnant women between 12-41 weeks of gestation and their fetuses were recruited. Measurements were made once at a randomly assigned gestational age specifically for the purpose of this study only. Due to unfavorable fetal position in some cases, BPD data were available in 613 measurements. Linear regression models were fitted separately to estimate the mean and standard deviation as functions of gestational age. Reference centiles were constructed from both equations, assuming the data were normally distributed. A new reference centiles chart for BPD is presented and compared with previously published data. Our derived centiles were clearly lower than those from Western studies showing the importance of racial differences between populations. This elucidates the need to develop fetal biometries charts specifically for each region.

Prenatal diagnosis for beta-thalassemia syndromes using HRP-labeled oligonucleotide probes at Siriraj Hospital.

Characterization of the molecular defect of beta-thalassemia in Thais has enabled us to establish prenatal diagnosis for homozygous beta-thalassemia and beta-thalassemia/Hb E. The nature of the beta-thalassemia mutation of each high risk couple or of the previous affected child was firstly identified after counseling. Detection of beta-thalassemia mutations was performed by dot-blot hybridization of the amplified DNA with a set of HRP-labeled ASO-probes specific for the common mutations. If the mutation could be characterized, prenatal diagnosis (PND) would be performed by using DNA extracted either from the chorionic villi (CVS) or amniotic fluid fibroblast in the first trimester of pregnancy or from fetal blood in the second trimester. DNA analysis was carried out in 23 couples at risk of having homozygous beta-thalassemia and 88 couples at risk for beta-thalassemia/Hb E. However, PND was performed by this technique in 22 pregnancies from 21 couples at risk of having homozygous beta-thalassemia children and 86 pregnancies from 71 couples at risk for beta-thalassemia/Hb E; 9 couples underwent more than one prenatal diagnosis. The results showed that, although there are more than 20 beta-thalassemia mutations in the Thai population, PND by DNA analysis could be carried out in more than 95% of the risk couples by using beta(E) and 10 different HRP-labeled ASO probes. This technique was simple, economic and avoided the use of radioactive isotope.

Prenatal diagnosis of thalassemia and hemoglobinopathies in Thailand: experience from 100 pregnancies.

In this review, we describe a simple strategy to detect the three severe thalassemic diseases commonly found in Thailand. Hb Bart's hydrops fetalis can be detected unambiguously by ultrasonography at 18-20 weeks of gestation or detected early in the first trimester by the gene amplification technique. Prenatal diagnosis for homozygous beta-thalassemia is better performed in the second trimester by in vitro protein synthesis. This is because the molecular defects of some beta-thalassemias are still unknown and homozygosity of the same mutation is low. In contrast, beta-thalassemia/Hb E is easily detected, in the first trimester, by direct visualization on electrophoresis or by dot blot analysis of enzymatically amplified DNA with a set of nonradioactively labeled oligonucleotide probes complementary to the most common mutations. We also found that the beta/gamma synthesis ratio in homozygous Hb E is similar to that of beta-thalassemia/Hb E and DNA analysis is the only method to distinguish these two conditions in the couple at risk of having either beta-thalassemia/Hb E or asymptomatic homozygous Hb E. In 100 pregnancies studied, the diagnoses were achieved in 96 pregnancies. Complications leading to fetal loss were found in 3 pregnancies: one woman developed amnionitis after fetal blood sampling; one had amniotic fluid leakage after the biopsy, and the third, carrying a normal fetus, aborted 10 days after fetal blood sampling with urinary tract infection and high fever. However, these figures are compatible with other reports and the risks are significantly lower than that of thalassemic disease the fetus is facing. One case of beta-thalassemia/Hb E was incorrectly diagnosed prenatally as being Hb E trait. In twenty-five pregnancies (25%) prenatally diagnosed to carry affected fetuses it was decided to have abortion. This study shows the feasibility of prenatal diagnosis for thalassemic diseases in Thailand which, in addition to screening and genetic counseling, can support prevention and control programs for thalassemia.

Percutaneous umbilical cord blood sampling.

Percutaneous umbilical cord blood sampling is a newer, safer, and more convenient technique and can be performed in the second and third trimester of pregnancy by direct puncture of the umbilical vein near its placental insertion, using a needle guided by ultrasound. Between 2-4 ml of pure fetal blood were obtained from 10 pregnancies at between 19 and 39 weeks' gestation. This new procedure offers access to the fetal circulation for diagnosis and therapeutic purposes.

Amniocentesis guided by ultrasound.

Abdominal amniocentesis was performed on 252 pregnant women at Siriraj Hospital during the period from August 1984 to July 1985, 227 cases for fetal lung maturity and 25 cases for genetic study in second trimester. Failure to obtain amniotic fluid encountered in 11 cases (4.36 percent) was directly associated with placental site, fetal position, amount of amniotic fluid and some technical error. Among the complication occurred in 4 cases (1.76 percent).There were premature rupture of membranes, chorioamnionitis, fetal trauma and one case of abortion in second trimester amniocentesis for chromosome study. The results of this study show that failure rate, bloody taped amniotic taped amniotic fluid and major complication can be reduced by using ultrasound guidance.

Chromosome study of partial hydatidiform mole: A case report.

A case of partial hydatidiform mole was admitted with hyperemesis gravidarum, human chorionic gonadotrophine was at high level. Ultrasonographic study showed the empty gestational sac with enlarged placenta which had cystic change in some area. The histologic study showed only hydatidiform mole but chromosome study confirmed classical partial hydatidiform mole which had a triploid (69 XXY) constitution. The clinical findings, ultrasound study and HCG level can emphasize this condition. Histologic and genetic study will confirm the diagnosis.

Partial hydatidiform mole: Report of 1 case.

A case of partial hydatidiform mole admitted with pre-eclampsia delivery of a living baby at 34 weeks was reported. Ultrasonographic study showed foetus with intrauterine growth retardation and cystic change of the placenta. The final diagnosis was made by pathologic histology. We suggested the clinical findings and ultrasonographic findings reminded the physician that some of this foetus has chromosome abnormalities. Correct diagnosis prenatally, will make the opportunity for the physician to manage such cases properly.