Chromosome aberrations in lymphocytes of residents living in buildings constructed with radioactively contaminated rebars.

Using the G-banding technique, we examined lymphocytes from 90 individuals (43 males and 47 females, median age 31 years) living in buildings constructed with radioactively contaminated rebars. Forty-five nonexposed control subjects (22 males and 23 females, median age 30 years), matched to the radiation-exposed individuals by sex and age, were selected for comparison. At least 500 metaphases were checked for each individual. All recognizable structural aberrations of chromosomes or chromatids were recorded. After adjusting for age and smoking status, both the percentage of cells with aberrant chromosomes (PCAC) and the number of aberrant chromosomes per 100 cells (NAC) were found to be significantly higher in the radiation-exposed females than in the control females (p < 0.05 for PCAC and NAC). This difference, however, was not observed in the comparison of radiation-exposed and control males. This suggests a possible interaction between sex and radiation exposure in their effects on chromosome aberrations.

Chromosomal fragile site expression in lymphocytes from patients with schizophrenia.

Schizophrenia is a common complex mental disorder. The lifetime prevalence of this disease is about 1% across different populations. The etiology is still unknown despite decades of intensive study. This report is aimed at studying the relationship between chromosomal fragile sites and the etiology of schizophrenia. Lymphocytes of 72 schizophrenic patients and 66 healthy controls were cultured in M medium, which is deficient in folic acid, and in medium RPMI 1640 with distamycin A. G-banding was carried out on 100 metaphases of each individual. Fragile sites were characterized as specific chromosomal bands that exhibit nonrandom gaps or breaks. Culture in M medium resulted in significant differences in the total number of chromosomal lesions and the total number of cells with chromosomal lesions between patients and controls (P<0.001), while no difference was noted after exposure to distamycin A. In the case of M medium, 17 bands in both patients and controls were recognized as expressing fragile sites nonrandomly using a statistical method based on the relationship of the binomial and F distributions. Further analysis using Fisher's exact test revealed a significant excess of expression of a rare fragile site at 2q11.2 among patients compared with controls (P<0.05). In the case of distamycin A induction, 13 bands were identified as having nonrandom expression of fragile sites using the same statistical method. A significant excess expression of a fragile site at 9q12 was identified among patients compared with controls by applying Fisher's exact test (P<0.001). Thus, our data suggest that chromosomal bands 2q11.2 and 9q12 are interesting regions that may harbor important genes associated with schizophrenia.

Chromosomal study in lymphocytes from subjects living or working in buildings constructed with radioactively contaminated rebar.

It has recently been found that many buildings in Taiwan were constructed with radioactively contaminated rebar, which raised great concern among the residents as well as governmental officials. In order to investigate the possible cytogenetic damage to the residents of contaminated buildings, a G-banding method was carried out on the lymphocytes of 30 radiation-exposed individuals from four families and one office building, as well as 15 control individuals from laboratory personnel. The estimated cumulative radiation doses for the exposed people range from 19.63 to 280.50 mSv. Altogether, 13 females and 17 males belonging to the radiation-exposed group, and 7 females and 8 males in the control group, were included in this study. With the exception of one sample, at least 500 metaphase spreads were scored and analyzed for each individual. All the recognizable structural aberrations of chromosomes or chromatids were recorded and statistically analyzed. Comparison of either percentage of cells with chromosome aberrations or number of aberrated chromosomes per 100 cells between the radiation-exposed and the control groups manifested insignificant differences (p = 0.1145 and 0.0766, respectively). In addition, the chromosomal regions close to the centromere were found to break more frequently than elsewhere in the genome.

Frequency and distribution of chromosomal integration sites of the Epstein-Barr virus genome.

Human lymphocytes can be transformed in vitro by integration of the Epstein-Barr virus (EBV) into the host genome. To study whether integration sites are stable or changeable in the course of long-term cultivation, three EBV-transformed lymphoblastoid cell lines, along with positive control (Namalwa cell line) and negative control (noninfected lymphocytes) cells were studied. A biotinylated Bam H1WEBV-DNA fragment was used as the probe for fluorescence in situ hybridization to count the numbers and to localize the sites of integrated EBV-DNA. Among these cell lines, the percentage of cells with integrated signals varied from 58% to 91%, with a mean of 1.43 to 2.66 signals per cell. No consistent tendency of increasing or decreasing number of signals was observed for the three cell lines harvested at four different cultivation intervals (86-204 days after infection). Although the integration was not site-specific, high frequencies of integration did occur in all three cell lines at the following chromosomal sites: 1p31, 1q31, 2q32, 3q13, 6q24 and 7q31. Because there were multiple integration sites present, it was difficult to draw any conclusion on integration site stability.

Absence of FMR-1 gene expression can be detected with RNA extracted from dried blood specimens.

Fragile X syndrome is a genetic disorder caused by abnormal function of the FMR-1 gene. The majority of fragile X syndrome patients carry an expansion of the CGG tri-nucleotide repeat in the FMR-1 gene, whereas others have a deletion or a point mutation in the FMR-1 structural gene. In this report, we analyzed a typical family with three male patients. RNA from Epstein-Barr virus transformed lymphoblastoid cells was used for RNase protection assay and reverse transcription-polymerase chain reaction (RT-PCR) analysis. Five normal individuals and one asymptomatic heterozygote from this family expressed detectable FMR-1 transcripts, whereas three fragile X patients showed no sign of expression with either assay. To extend the application of this PCR-based assay to laboratory diagnosis of fragile X syndrome, we confirmed that dried blood samples collected on screening filter papers for newborns are an adequate source of RNA for RT-PCR. Moreover, fragile X patients from the study family and another family were reliably identified by the absence of the FMR-1-specific PCR product from the dried blood specimens. Our studies indicate that this simple assay can be used to diagnose the fragile X syndrome for the majority of male patients.

Cytogenetic Study of Mentally Retarded Children in Taipei.

560 blood samples collected from mentally retarded children in Taipei were karyotypically analyzed for the incidence of fragile X and other chromosome abnormalities. The fragile site at Xq27.3 was observed in 18 patients (3.21%), 11 males and 7 females, out of the 560 blood cultures using M medium. Down syndrome (6.25%), 24 males and 11 females, was the other major category of abnormality. Other abnormalities, including inversion, translocation, deletion, duplication, ring as well as an extra marker chromosome were observed. The overall incidence of chromosomal abnormalities in these children was 14.82%. Copyright 1994 S. Karger AG, Basel

Karyotypic analysis of seven established human esophageal carcinoma cell lines.

Fifty metaphases from each of seven esophageal carcinoma cell lines (TE-1, TE-4, TE-5, TE-6, TE-9, HCE-6, and HCE-8) were karyotypically analyzed for both numerical and structural chromosomal abnormalities. The modes of numerical variation found in the TE cell lines were as follows: 1) a wide range of variation in chromosome numbers (45-100)/cell with a modal number of 52 (TE-1); and 2) a narrow range of variation at the hypertetraploidy level (TE-4), hypotriploidy level (TE-5 and TE-6) and hypertriploidy level (TE-9). The distribution of chromosomal number/cell in cell lines HCE-6 and HCE-8 was extremely diverse. It was difficult to find a modal number in the range of 94-117 in the HCE-6 line or in the range of 45-52 in the HCE-8 line. The structural changes were extensive in all of these cell lines. Chromosomes most frequently involved in the structural changes were 1, 2, 3, 6, 7 and 9. Most of these abnormalities resulted from simple deletion, duplication, insertion, inversion or translocation. A few of them were complicated rearrangements. No breakpoint was shared by all of the cell lines.

A method for testing the nonrandomness of chromosomal breakpoints.

Testing the nonrandomness of breakage at a chromosome band is an essential step fo identifying a fragile site. In this paper, we propose a method derived by using the relationship between the binomial and F distributions for testing nonrandomness. The method is simple in calculation. It was applied to the detection of fragile sites for Chinese patients with colorectal carcinoma.

Chromosomal screening of mentally retarded school children in Taipei.

The major concern of the national population policy in Taiwan in recent years has been to lower the incidence of hereditary diseases and mental retardation in the general population. It has been estimated that there are around 10,000 mentally retarded school children in Taiwan. If effective chromosomal screening can be extended to these children, some of the family members who are carriers of balanced chromosomal rearrangements may benefit from follow-up studies and genetic counseling. The present report is the result of a pilot study conducted from 1988 to 1991 to explore the possibility of chromosomal screening of mentally retarded school children in Taipei. A total of 871 blood samples were collected from 1,147 children registered in 46 schools or residing in homes for the retarded. Chromosomal analysis was successfully accomplished on 674 out of 871 blood samples. The following chromosomal abnormalities were observed: 28 Down's syndrome, four Klinefelter syndrome, one XYY, one triple X, 11 translocations, seven inversions, four mosaics, three duplications, one deletion and one with an extra marker chromosome. After follow-up cytogenetic analyses of 13 families with probands with structural chromosomal anomalies, three of these families were shown to have one or two carriers of balanced translocated chromosomes. It seems that the present screening system would not be practical or cost-effective if it were applied island-wide in the future.

Association between glucose-6-phosphate dehydrogenase deficiency and neonatal jaundice: interaction with multiple risk factors.

This nonconcurrent cohort study was carried out to evaluate the association of neonatal jaundice with glucose-6-phosphate dehydrogenase (G-6-PD) deficiency and its interactions with other risk factors. The G-6-PD enzyme activity of 12,379 neonates was screened by a semi-quantitative fluorometric assay and double-checked by a quantitative method to identify a G-6-PD deficient cohort of 333 neonates. Matched with these on birth date, sex and delivery hospital were a G-6-PD normal cohort of 653 neonates. Neonatal jaundice was defined by a peak serum bilirubin (PSB) level of > or = 15 mg/dl. A significant association between G-6-PD deficiency and neonatal jaundice was observed in male but not female neonates. There was an inverse dose-response relation between G-6-PD activity and neonatal jaundice among male neonates. Both hypoxia/asphyxia and maternal hepatitis B surface antigen (HBsAg) carrier status were associated with an increased risk of neonatal jaundice among G-6-PD deficient but not G-6-PD normal male neonates. Based on multiple regression analyses, an additively synergistic effect on PSB level and severe jaundice (PSB > or = 20 mg/dl) was observed for G-6-PD deficiency and maternal HBsAg carrier status.

PIP: Researchers compared data on 333 newborns with glucose-6-phosphate dehydrogenase (G-6-PD) deficiency at 5 public and 5 private hospitals in Taiwan with data on 653 birth date, sex, and delivery hospital matched newborns to examine the peak serum bilirubin (PSB) level and incidence of neonatal jaundice of both G-6-PD deficient and G-6-PD normal newborns. They also wanted to determine whether an association exists between G-6-PD activity level and incidence of neonatal jaundice and associations between G-6-PD deficiency and other likely risk factors of neonatal jaundice. A significant association between G-6-PD deficiency and neonatal jaundice existed among male neonates but not female neonates. Male neonates had a considerably higher incidence of neonatal jaundice than did female neonates (11.6% vs. 6.2%). There was a significant inverse dose-response relationship between G-6-PD activity and neonatal jaundice among the male neonates (p.01). For example, the relative risk was 1.78 for 20.1-29.9 relative intensity, 2.01 for 15.1-20, 2.61 for 10.1-15, and 4.07 for 10. Maternal hepatitis B surface antigen (HBsAg) carrier status and hypoxia/asphyxia significantly increased the risk for G-6-PD deficiency in male neonates (p.05). The multiple regression analysis indicated a significant effect of G-6-PD deficiency on the PSB level and the incidence rate of severe neonatal jaundice. There was a similar significant interaction between G-6-PD deficiency and maternal HBsAg carrier status.

Double NOR is not a good indicator of risk for Down syndrome.

The silver staining technique was applied to study the nucleolar organizer regions (NORs) of 38 parents of children with Down syndrome and 40 parents of healthy offspring. Double NOR (dNOR) variants were found in both groups of parents. We compared the incidence of dNOR between these two groups. Our results indicate that different conclusions can be drawn from the same data depending on how the analyses are carried out. It seems to us that dNOR is not a useful marker for predicting whether or not its carrier is at a higher risk of having children with Down syndrome.

Chromosomal and biochemical screening on mentally retarded school children in Taiwan.

Governmental officials as well as medical scientists in Taiwan have worked hard in recent years to develop and to implement various measures, such as prenatal diagnosis and neonatal screening, to lower the incidence of hereditary diseases and mental retardation in the population. An inquiry into the possibility of devising a chromosomal and biochemical screening program and to apply it routinely to all the mentally retarded school children island-wide was the major aim of the present study. A collection of 1,614 blood samples was screened for phenylketonuria (PKU), galactosemia, homocystinuria, biotinidase deficiency, and congenital hypothyroidism. The IQ of these children ranged from 50-75 (1,397 children, moderate group) to less than 50 (217 children, severe group). Six cases of PKU (one tetrahydrobiopterin deficient and five classical) and three cases of thyroid dysfunction were found. The overall incidence of these two diseases was 0.56%. Of the 1,614 blood samples, 1,323 were cultured and karyotyped successfully. One hundred and twenty-five of them had chromosome abnormalities. The majority (64 out of 125) were trisomy 21. A remarkable difference in the percentage of mentally retarded children with chromosome abnormalities was observed between the moderate (7.87%) and severe (17.51%) retarded.

Chromosome analysis on two long-term established human colorectal carcinoma cell lines.

A chromosomal analysis was carried out on two colorectal carcinoma cell lines (WiDr and COLO 205), which were established 15-20 years ago in the US and were collected by the Cell Bank of the Veterans General Hospital in Taipei. Among the 200 cells counted, 65.5% of WiDr (male) had 68-73 chromosomes, while 74% of the COLO 205 (female) had 70-76 chromosomes per cell. The Y chromosome was absent in the 30 WiDr metaphases analyzed. None of the other chromosomes, including X and the autosomes of both WiDr and COLO 205, revealed such a numerical deficiency. Over half of the autosomes had an average number per cell above 2.0. The existence of 5 or 6 normal homologues for certain autosomes was not rare in either line. Numerous structural abnormal marker chromosomes were present in the cells. As compared with the original chromosome findings which were done over 10 years ago, we noted that the range of chromosome counts was wider and the number of marker chromosomes increased in these long-term cultivated cell lines.

A human hepatocellular carcinoma cell line with multiple copies of structurally normal chromosomes.

At Veterans General Hospital (VGH), a cell line, HA59T(HA59T/VGH), was established from a primary hepatocellular carcinoma of a 52-year-old Chinese male patient. G-banded metaphases were analyzed at passages 12 and 62. Of the 200 cells counted, 68% had 100-110 chromosomes/cell at passage 12, and 74% had 90-100 chromosomes/cell at passage 62. The presence of multiple copies of a structurally normal chromosome in a single cell was common for most of the chromosomes. Both X and Y sex chromosomes were normally present in the majority of the cells. This cell line is karyotypically different from those reported in other literature.

Karyotypic characterization of an established human hepatoma cell line HA22T/VGH.

The karyotype of an established human hepatoma cell line HA22T/VGH was characterized by G-banding. A majority of the 200 cells counted had around 70 chromosomes at passage 24, and 60 at passage 338. Of the 50 cells karyotyped from each of passage 24 and passages 338-339, chromosomes #13 and #18 were absent. The presence of the Y chromosome was reduced dramatically from a mean value of 1.12/cell at passage 24 to 0.12/cell at passages 338-339. In general, most of the chromosomes--particularly chromosomes #5, #7, #9, #15, and #21--tended to be less represented in the course of propagation in vitro. The presence of multiple copies of a normal chromosome in a single cell was quite common for chromosomes #5 and #7 at both early and late passages. Numerous structural rearrangements of the chromosomes were observed.

A Chinese family with phenylketonuria and maternal phenylketonuria detected by family screening.

A 16-year-old boy with classical phenylketonuria (PKU) and mild mental retardation (IQ 69) was detected by the screening of mentally retarded school children in Taiwan with Guthrie's bacterial inhibition assay. The follow-up family study showed that one of his married elder sisters suffered from borderline mental retardation (IQ 75) and was also diagnosed as a classical case of PKU. She had borne one boy and one girl, both suffering from mild mental retardation, microcephaly, delay in linguistic development and severe growth retardation. This is the first known Chinese family with maternal PKU. To prevent future mental retardation caused by maternal PKU, the simultaneous establishment of a register system with a neonatal screening programme, is indicated for the follow-up of PKU girls, screening of the whole family of newly discovered PKU cases, and to exclude unrecognized maternal PKU in women who have given birth to a microcephalic child.

Chromosome analysis on a cell line (CE48T/VGH) derived from a human esophageal carcinoma.

The cell line CE48T/VGH was established from an epidermoid carcinoma of the middle third of the esophagus of a 58-year-old male patient. Cytogenetic analysis at passages 90-99 showed that the line was hypotetraploid, with a mean chromosome number of 73. None of the 50 karyotyped cells had a normal chromosome #1 or Y. Cells with multiple copies of some of the autosomes were observed frequently. Structural rearrangements were numerous, especially of chromosomes #1, #9, #14, X, and Y.

A chromosomal study on blood lymphocytes of patients poisoned by polychlorinated biphenyls.

Chromosome studies were carried out on peripheral blood lymphocytes from 36 PCB-poisoned patients and on ten PCB-unexposed healthy controls. Nineteen out of 36 patients (52.7%) had either chromosome or chromatid aberrations, while none of the controls had. The highest percentage of cells with chromosome or chromatid aberrations in a single individual was 34.0. The blood PCB level ranged from 6.4 to 101.8 ppb, with a mean of 34.1 ppb. No correlation was observed between the level of blood PCB and the presence or absence of chromosome or chromatid aberrations.