Analysis of beta-thalassemia mutations and beta-locus control region hypersensitive sites 2, 3 and 4 in southern Thailand.

beta-Thalassemia mutations in 221 chromosomes of unrelated southern Thai patients were analyzed. Using dot blot hybridization of PCR amplified DNA with 15 allele specific oligonucleotide probes for beta-thalassemia mutations 196/221 (89%) of the alleles were characterized. Ten mutations were identified, of which six [codon 41/42 (TTCTTT-TT), IVS1 nt5(G-C), codon 19 (AAC-AGC), codon 17 (AAG-TAG), IVS1 nt1(G-T), -28 TATA (A-G)], accounted for 85%. Among the 25 uncharacterized alleles, 15 were analyzed by automated fluorescent DNA sequencing of the whole beta-globin gene with normal results in 7 alleles. Four mutations, previously described were detected in 8 alleles. They were a G-A at IVS1 nt1 in one heterozygote, a G-T at IVS1 nt1 in one heterozygote, codon 15 (TGG-TAG) in two heterozygotes and poly A(AATAAA-AATAGA) in two homozygotes. The polyadenylation mutations, previously demonstrated in the Malaysian population have been first detected in Thailand. It is remarkable that the IVS1 nt1 (G-A) mutation, previously reported in the Mediterranean population has been found only in the south of Thailand. This mutation was probably imported from Portugal. In former times the Portuguese had settled in Phuket in southern Thailand. In order to find a causative mutation in the rest of 7 true unknowns we performed direct DNA sequencing of the core fragments of the beta-Locus Control Region Hypersensitive Sites (LCR HS) 2,3 and 4 in these 7 samples. DNA sequencing of HS2 and HS3 fragments showed normal results. The heterozygote A/G was present in the palindromic sequence of the LCR HS4 (TGGGGACCCCA) in 6 beta-thalassemia samples. The same heterozygote A/G was found in 5/12 normal subjects. The allele frequency of A (0.79) is obviously higher than that of G (0.21). This could be due to the stability of the palindromic structure. When an A is in the middle of the palindromic sequence, the hairpin structure is formed. In contrast the hairpin structure disappears when a G is in the middle of the palindromic sequence. This structure is not further symmetric and may not be so stable as the hairpin structure. beta-Thalassemia mutations in southern Thailand are very heterogeneous and their distribution is different from other parts of the country.

The frequency of fragile X syndrome among selected patients at Songklanagarind Hospital during 1991-1996, studied by cytogenetic and molecular methods.

Fragile X syndrome is the most common inherited form of mental disability, world-wide. Main clinical features are cognitive deficit, speech difficulties, delayed development, autism, and particular physical characteristics. The syndrome can be cytogenetically diagnosed by the expression of chromosome X fragile site at band Xq27.3. At molecular level, the cause of the syndrome is defined as an abnormal expansion of CGG trinucleotide repeats in the 5'UTR of the FMR-1 gene as well as hypermethylation at the proximal CpG island. Study of fragile X syndrome at Songklanagarind Hospital during May 1991-June 1996 was herein reported. A total of 287 blood samples of 260 unrelated families were cytogenetically examined by using lymphocyte culture method with 2-4 different treatments. Frequency of positive fragile X cases was found to be 7 in 260 (2.7%). Among relatives of the positive ones, 13 individuals were also positive. Other types of chromosome abnormalities were detected in 13 cases (5%). For molecular study, DNA samples were obtained from 97 cases. Investigation of CGG repeat expansion was performed by PCR method. Abnormal expansion was identified as full mutation (> 200 repeats) and premutation (> 50-200 repeats). The abnormalities were found in 14 individuals of 5 unrelated cases; 6 with full mutation and 8 with premutation. No molecular study on the two cytogenetic positive cases has been performed. In conclusion, a total of 50 individuals with fragile X abnormality has been documented: 18 affected cases and 32 carriers. Investigation of the remaining suspected members in positive families is in progress. The information and experience will lead to prevention of this genetic disease by prenatal diagnosis and elective abortion in Thailand.

Alpha-thalassemia incidence in southern Thailand by restriction endonuclease analysis of globin DNA from placental blood at Songklanagarind Hospital.

The incidence of alpha-thalassemia has been studied previously based on the levels of Hb Barts' in cord blood. This method is an inadequate indicator of alpha-thalassemia. Thus in this study we use DNA analysis to get more accurate data. Hb Barts' was detected in placental blood samples from 15.5% of 375 infants born at Songklanagarind Hospital. The white blood cell DNA of 300 samples was studied for alpha-globin gene deletions by hybridization of DNA fragments digested by the restriction endonuclease Eco RI with specific 32P-labled zeta-globin gene probe. The incidence of alpha-thal 2 and alpha-thal 1 traits were 12.0% and 4.3%, with the gene frequencies 0.0650 and 0.0217 for -alpha/and --/, respectively. The incidence of HB CS trait was 5.8%, with the gene frequency of 0.0292 for alpha cs alpha/. We also found that the incidence of the triplicated zeta and triplicated alpha were 14.7 and 1.0%, with the gene frequencies of 0.0733 and 0.0050 for zeta zeta zeta/and alpha alpha alpha/, respectively. The DNA lesion of alpha-thalassemia in the south is similar to the study of Tanphaichitr et al (1988) in central Thailand. Knowledge of alpha-globin gene deletion would be useful for prenatal diagnosis of Bart's hydrops to prevent toxemia of pregnancy in the south of Thailand.

Traumatic abdominal wall hernia.

Two cases of traumatic abdominal wall hernia, produced by impaction of the motorcycle handlebars, are reported. The mechanism of injury, clinical and radiologic diagnosis are discussed. Because of the high incidence of other associated intraabdominal injuries, early exploration and repair through a midline incision is advocated. Adequate debridement and solid repair of fascial planes with non-absorbable sutures are required to prevent recurrence. Primary closure of the musculofascial defect was performed in both reported cases and the recovery was uneventful.

The spectrum of beta-thalassemia mutations in southern Thailand.

Beta-thalassemia mutations in 282 alleles of 253 unrelated individuals originating from various provinces in the south of Thailand were characterized by dot blot hybridization, specific PCR-amplification and direct DNA sequencing. It was possible to characterize the mutations in 274 (97.2%) of alleles studied. Twelve different point mutations and two different large deletions of the beta-globin gene were identified. Seven common mutations, namely 4 bp deletion at codons 41/42. IVS1 position 5 (G-C), codon 19 (AAC-AGC), codon 17 (AAG-TAG), IVS1 position 1 (G-T), position -28 (A-G) and 3.5 kb deletion, accounted for about 91.5%. The mutations at mRNA cap site + 1 (A-C) and IVS1 position 1 (G-A), previously undescribed in Thailand, were found in 1 and 2 individuals, respectively. A novel mutation of 105 bp deletion at the 5' end of beta-globin gene was detected in a family originating from this area. The knowledge from this study should be useful for planning of genetic counseling and prenatal diagnosis programs for patients with beta-thalassemia in the south of Thailand.

Torsion of the gallbladder.

Torsion of the gallbladder is a surgical emergency that occurs predominantly in the elderly. Accurate preoperative diagnosis is difficult, and delay in cholycystectomy can result in a fatal outcome. Removal of the gallbladder before the onset of gangrene or rupture of the organ is the only effective treatment.

Splenic cystic lymphangiomatosis: an unusual cause of massive splenomegaly: report of a case.

A 29-year-old woman had a history of an upper quadrant abdominal mass for about 6 years. An ultrasound examination revealed splenomegaly containing several cysts. On exploratory laparotomy, multiple cysts were found in the spleen. Because of the extensive involvement of the spleen, splenic salvage could not be performed, and total splenectomy was done. Both morphological and histological features of the removed spleen were typical of cystic lymphangiomatosis.

Molecular heterogeneity of beta-thalassemia in Thailand.

beta-Globin genes in 294 chromosomes of beta-thalassemia homozygotes and patients of beta-thalassemia/HbE in the northeast, the middle and the south of Thailand were analyzed by the PCR related techniques: dot blot hybridization, direct restriction assay, direct cloning and direct sequencing of the amplified DNA fragments. Twelve different mutations were detected at various frequencies. They are an A-G at-28, codon 19 (AAC-AGC), a G-T at IVS-1 nt1,a G-C at IVS-1 nt5, a C-T at IVS-2 nt654, a G addition in codons 8/9, a C deletion in codon 41, a 4 bp deletion in codons 41/42, an A addition in codons 71/72, an AAG-TAG in codon 17, a CAG-TAG in codon 26, a TAC-TAA in codon 35 and a 8 bp deletion in codons 123-125. We also developed allele specific-polymerase chain reaction to facilitate non-radioactive detection of the mutation. Origins and spread of mutations are speculated based on the results of determination of haplotypes and frameworks that are linked to the thalassemia alleles.

The problem of thalassemia in Thailand.

About one per cent of the Thai population are affected with thalassemic diseases. In each year there are almost 50,000 pregnancies at risk of having an affected fetus, one fourth of which result in thalassemic newborns. Both alpha- and beta -thalassemia, including hemoglobins E and Constant Spring, are common in Thailand. Their distribution varies from region to region and among different ethnic groups. About 30-40% of the population are carriers of at least one of the abnormal genes. Thalassemias and hemoglobinopathies are common and heterogeneous in Thailand. They combine to give more than 60 thalassemic syndromes with varying clinical severity. Abnormalities can be detected in every organ system. Studies in detail into each clinical problem will lead to better management. Hematological and molecular studies on different types of thalassemia in Thailand have made it possible to give prenatal diagnosis service to those pregnancies at risk of having a thalassemic child. Sporadic services have been given in three centers. Systematic prevention and control program is being planned by the cooperation of both the public and private sectors.

Chromosome analysis of 894 patients.

Metaphase chromosome analysis from cultured blood lymphocytes was performed in 894 consecutive patients from the year 1981 to early 1989. G-bands by trypsin using Giemsa (GTG) was routinely employed during the last five years supplemented with other banding techniques if required. High resolution chromosome banding was performed in cases suspected of structural chromosome abnormality. Successful studies were obtained in 862 (96.4%). Out of the successful cases, 232 (26.9%) had informative results, and 193 (22.4%) had chromosome abnormalities. Down's syndrome was found in 110 cases. Edwards' and Patau's syndromes were found in 4 and 7 cases respectively. A case of trisomy 14 mosaic was found. There were 2 cases of trisomy 22 syndrome, one case with 46,XX/47,XX,+mar(22) and another case with 46,XX/47,XX,+r(22) karyotype. There were 39 cases of sex chromosome abnormalities, 27 of which had Turner's syndrome. Kline-felter syndrome was found in 8 patients. Triple X syndrome and true hermaphrodite (46,XX/46,XY) was each found in one case. Autosomal deletions were found in 19 patients. Autosomal duplications were found in 4 patients, and autosomal translocations were found in 10 patients. Some of these autosomal structural abnormal cases have been included in the chromosomal syndromes mentioned above.

G-6-PD variants in Chinese in Thailand.

Partial purified erythrocyte G-6-PD from 25 G-6-PD deficient southern Chinese male residents in Thailand was characterized. Five G-6-PD variants were found : G-6-PDs Canton (8), Dhon (or Taipei-Hakka) (8), Mahidol (or B (-) Chinese) (6), Haad Yai (1), and Hong Kong (1). One person whose enzyme was not fully characterized might have G-6-PD Haad Yai or a new variant.