Genetic counseling for thalassemia in Thailand: problems and solutions.

Thalassemia, a hereditary anemia, has been a major public health problem in Thailand and Southeast Asia for decades, yet the prevalence of thalassemia in Thailand is not decreasing due to lack of awareness of this disease in Thai population, which implied that genetic counseling was a failure. We determined the problems and obstacles in thalassemia counseling in Thailand and proposed the possible solutions in order to deliver genetic counseling and services to the communities more efficiently. A survey in thalassemia services was carried out in 12 hospitals; 9 in Bangkok, 3 in the North, Northeast, and South of Thailand respectively, by using questionnaire designed to assess the healthcare system, characteristics of target population, methods of genetic counseling, knowledge and attitudes of counselors, thalassemia support group, and researches in thalassemia, in a cross-sectional descriptive research design. The main problems in genetic counseling for thalassemia in Thailand are the followings; thalassemia problems not visible to the administrators, unorganized teamwork and services, lack of knowledge and inadequate numbers of counselors, lack of thalassemia support group, and inadequate researches in thalassemia prevention and control. The possible solutions are proposed. This study has pointed out the unseen problems and obstacles, along with the solutions in genetic counseling, given correctly, will help create awareness of thalassemia impact on health and socioeconomics in the Thai population. Thus, genetic counseling, with well-established guidelines, is a critical component for the success of prevention and control of thalassemia in Thailand.

Prenatal prediction of spinal muscular atrophy by SMN deletion analysis.

The objective of this study was to provide prenatal prediction of spinal muscular atrophy (SMA) by survival motor neuron (SMN) gene deletion analysis and genetic counseling in families with previous child affected with SMA. The SMN gene is absent or interrupted in approximately 95% of SMA patients independence of clinical severity. We study four families with one previous child affected in each by performing the SMN deletion analysis in the index case. When a homozygous deletion in exon 7 or exon 8 is found, we offer prenatal prediction to the family. All four index cases had homozygous deletions of the SMN gene. Prenatal diagnosis by amniocentesis was performed in all pregnancies. Two pregnancies were positive for the homozygous deletion of the SMN gene, non-directive counseling was given and the two pregnancies were terminated. The other two pregnancies showed no deletion of the SMN gene. The unborn child is yet to be followed up. The prenatal prediction of SMA shows considerable requirements and potential effectiveness in prevention of the SMA in families at risk which cut the cost of care in this incurable disease.

First trimester prenatal diagnosis by transcervical chorionic villus sampling using curved biopsy forceps: lessons of the first 30 continuing pregnancies.

Transcervical chorionic villus sampling was performed on 30 pregnancies who were at risk for chromosomal abnormalities between 9 and 12 weeks of gestation to determine whether the developing fetus had a chromosomal disorder. Curved biopsy forceps were passed transcervically into the chorion frondosum under continuous real-time ultrasound guidance, and chorionic villi were biopsied. Chorion yield was assessed semiquantitatively. An adequate villus sample was obtained in all cases, giving a success rate of 100 per cent. The average weight of the villi was 18.8 mg with a lower limit of 10 mg which proved sufficient for diagnostic purposes. The villi were processed for chromosomal analyses by cultured preparations. A diagnostic result was achieved in 28 of cases (93.3%) within 2 weeks. No major maternal complications were encountered. The fetal loss rate was 3.3 per cent. No fetal anomalies were found in the study group. It is concluded that transcervical chorionic villus sampling appears to be a relatively safe and reliable procedure, but the risk of miscarriage can only be accurately assessed after further investigation. In contrast to amniocentesis, the procedure is performed early in pregnancy and results of the genetic test are available during the first trimester. We believe that transcervical chorionic villus sampling offers an alternative to amniocentesis in the detection of genetic disorders.

Rapid karyotyping in the second and third trimesters for fetuses at risk of chromosomal abnormalities at Chulalongkorn Hospital.

Transabdominal fetal blood sampling under ultrasonic guidance was performed in 20 fetuses at 18 to 34 weeks gestation. Pure fetal blood was obtained in all cases; 11 from the umbilical veins at the placental cord insertion, 7 from the fetal intrahepatic veins and 2 from the fetal hearts. Rapid karyotype was obtained within 7 days by fetal lymphocyte culture. Chromosomal abnormality was detected in 5 (25.0%) fetuses. Abnormal karyotype was found in 4 of 8 fetuses with structural malformations detected by antenatal ultrasound and in 1 of 5 fetuses of elderly mothers at advanced gestational ages. This suggested that in fetuses at risk of chromosomal abnormality, rapid karyotype should be obtained and fetal blood sampling is justified in the second or third trimester.