Ataxia telangiectasia: G2 checkpoint and chromosomal damage in proliferating lymphocytes.

There is a checkpoint pathway in eukaryotic cells that depends on ATM (ataxia telangiectasia mutated) kinase which activates the processes leading to the repair of DNA damage and also lengthens the G(2) stage of the cell cycle. In cells from ataxia telangiectasia patients, due to their lack of active ATM kinase, an increase in chromosomal aberrations and a failure to induce G(2) lengthening could be expected. However, the basal G(2) timing in ataxia telangiectasia cells was longer than in controls and was further extended after X-ray irradiation (0.4 Gy), although to a lesser extent than in controls. Moreover, in control cells caffeine shortened G(2) and increased chromosomal damage 7-fold, while in ataxia telangiectasia cells caffeine only trebled aberration yield without shortening G(2). As caffeine is an inhibitor of ATM kinase, these results suggest the existence of some redundant ATM-independent checkpoint in G(2) of ataxia telangiectasia cells. The differential response to caffeine of ataxia telangiectasia and control lymphocytes may be explained by the presence of two different subpathways in the G(2) checkpoint: one regulating the processing and repair of damaged DNA and the other controlling G(2) timing. While in controls both subpathways may be mediated by ATM kinase, in ataxia telangiectasia cells caffeine-sensitive ATR kinase and the caffeine-insensitive DNA-PK kinases might be responsible for DNA repair and the G(2) delay subpathways, respectively. Confirmation of this model in ataxia telangiectasia cells with another cell type in which both subpathways are mediated by DNA-PK should define whether a metylxanthine such as caffeine may also have an additional direct inhibitory effect on DNA repair.

Familial dup(8)(p12p21.1): mild phenotypic effect and review of partial 8p duplications.

We describe a family with direct transmission of a duplication of 8p12-->8p21.1. The phenotype of affected relatives included mild mental retardation but no minor anomalies. The duplication was identified by means of GTG-banding and fluorescence in situ hybridization with a probe specific for 8p12 generated by microdissection and degenerate oligonucleotide primed-polymerase chain reaction. Assay of glutathione reductase, which has been localised to 8p21.1, was significantly increased when compared with controls with normal chromosomal constitution. To the best of our knowledge, a proximal direct duplication of 8p restricted to subbands p12-->p21.1 has not been reported so far. The reported aberration is compared with other partial duplications of 8p, in particular to inversion duplications 8p and to small direct distal duplications involving 8p23.1. Am. J. Med. Genet. 94:306-310, 2000.

Antioxidant enzymes and their implications in pathophysiologic processes.

Aerobic organisms possess antioxidant defense systems that deal with reactive oxygen species (ROS) produced as a consequence of aerobic respiration. Reactive oxygen is related to both, the arrest of growth and the start of cell differentiation. Low concentrations of reactive oxygen intermediates may be beneficial or even indispensable in processes such as intracellular messaging and defense against micro-organisms, but higher amounts of active oxygen may be harmful to cells and organisms. A wide array of non-enzymatic and enzymatic antioxidant defenses exists, including superoxide dismutase (SOD), glutathione peroxidase (GPX) and catalase (CAT). We describe their main characteristics and how these antioxidant enzymes work together against active oxygen. Small deviations from their physiological values may have a dramatic effect on the resistance of cells to oxidative damage to lipids, proteins and DNA. Consequently, toxic oxygen play a role in aging process as well as in a number of human diseases that we list in this review.

D8S7 is consistently deleted in inverted duplications of the short arm of chromosome 8 (inv dup 8p).

Ten patients with inverted duplication of 8p (inv dup 8p) were studied with cytogenetic, biochemical and molecular techniques. The duplication for the region 8p12-p22 was always associated with a deletion of the locus D8S7 (mapped in 8p23.1) as demonstrated with the probe pSW50 by both in situ hybridization and Southern blot. Restriction fragment length polymorphisms detected by probes pSW50 (1 case) and by pG2LPL35 (locus LPL) (two cases) were informative as to a maternal origin of the anomaly. The activity of glutathione reductase, whose gene maps in the duplicated region at 8p21.1, was increased in all patients. The recognizable phenotype of inv dup 8p includes neonatal hypotonia, prominent forehead, large mouth with everted lower lip, abnormally shaped large ears, brain malformations and severe mental retardation. Our findings indicate that the chromosome rearrangement is homogeneous at least for the presence of the deletion and support the hypothesis of a common mechanism of origin.

Amniotic fluid microvillar enzyme activity in fetal malformations.

Prenatal diagnosis of cystic fibrosis based on amniotic fluid microvillar enzyme activity assay has become routine practice in the past few years. Normal (median) values of these enzymes were determined in 177 normal healthy pregnancies between 15-20 gestational weeks and were related to enzyme values measured in 50 pregnancies complicated with congenital malformations, 6 monogenic inherited diseases and 4 chromosomal aberrations. It is concluded that increased trehalase activity has diagnostic importance in detecting fetal kidney diseases, and radial-renal syndrome (with elevated GGT activity), while low enzyme activities may indicate chromosomal aberrations (with no signs of intestinal obstruction). With the collection of further data, the analysis of these enzymes might provide an opportunity to set up diagnostic procedures for the detection of other, non-CF-related cases.

Superoxide dismutase activity and chromosome damage in cultured chromosome instability syndrome cells.

The basal levels of superoxide dismutase (SOD) activity and chromosome aberration (CA) and sister-chromatid exchange (SCE) frequencies were examined in cultured fibroblasts or Epstein-Barr virus (EBV)-transformed lymphoblastoid cell lines (LCLs). These cells were derived from patients with chromosome instability syndromes (CISs) including Bloom's syndrome (BS), Fanconi's anemia (FA) and ataxia telangiectasia (AT). Embryonal fibroblasts and LCLs from normal subjects served as controls. Although LCLs tended to exhibit a higher SOD level than fibroblasts due to an elevation of Cu/Zn-SOD activity, BS and FA fibroblasts with increased frequencies of CAs and/or SCEs showed abnormally elevated SOD activity due to the manifold increase of Mn-SOD levels compared with control cells. However, BS and AT LCLs with almost control levels of CA and SCE frequencies showed no, or a slightly elevated, SOD activity, suggesting a possible selection of such cells during EBV transformation. The observed parallelism between the SOD activity and the cytogenetic manifestation may imply an involvement of active oxygen species, especially superoxide radicals, in the increased chromosome damage of CIS cells.

The decrease of catalase or esterase D activity in patients with microdeletions of 11p or 13q does not increase their radiosensitivity.

Lymphocyte cultures from patients affected by retinoblastoma (Rb), with or without a microdeletion of chromosome 13, and Wilms tumor (WT), with a microdeletion of chromosome 11p where exposed to gamma-ray radiation during S and G2 phases. Chromatid and chromosome lesions were scored and compared to those observed in controls. No significant differences were detected, neither between patients and controls, nor between patients carrying or not a microdeletion. This lack of difference was unexpected since the genes for catalase and esterase D, also called S-formyl glutathione hydrolase, which are two detoxication enzymes, are deleted in case of microdeletion of 11p and 13q, respectively.

Nonspecific esterase of acute promyelocytic leukemia (M3).

Leukemic cells of 43 patients with acute promyelocytic leukemia (M3) were investigated morphologically and cytochemically to determine the percentage of aberrant enzymes and whether or not the presence impacts on the clinical outcome. Twelve patients (27.9%) showed alpha-naphthyl acetate esterase (ANAE) activity in their leukemic cells, and two of these cases revealed remarkably low myeloperoxidase (MPO) positivity, a pattern seen in monocytic precursors. However, further cytochemical evidence for this monocytic feature, the inhibition of naphthol AS-D acetate esterase (NASDA) activity with sodium fluoride (NASDA-F), was found in only five of these nine patients. In 31 cases (72.1%), there was minimal ANAE activity. Of interest, two of these were devoid of naphthol AS-D chloroacetate esterase (CAE), which is prominently displayed in neutrophilic granulocytes, even though these leukemic cells were 100% intensely positive for MPO activity. Between the two groups with and without ANAE activity, there were no remarkable differences in the distribution of sex and age, hematological findings, and rates of complete response. Our study has confirmed the cytochemical heterogeneity of M3 with no obvious relationship between this heterogeneity and early therapeutic outcome.

A new cell line of murine myeloid leukemia with A-type phosphoglycerate kinase as marker isoenzyme.

A new murine myeloid leukemia cell line (C2M) with A-type phosphoglycerate kinase (PGK) as marker isoenzyme was established from myeloid leukemia which arose in a female C3H/He strain mouse of the genotype Pgk-1a/Pgk-1b 1 yr after a whole body X-irradiation of 3 Gy. Cytochemical stainings indicated that C2M cells had myelomonocytic characteristics. Chromosomal analysis showed the partial deletion of No. 2 chromosome. Intravenous injection of C2M cells resulted in the development of myeloid leukemia in syngeneic mice owing to the growth of C2M cells. When C2M cells were transplanted to C3H/He mice with B-type PGK, PGK of spleen expressed two bands on electrophoresis; A-type PGK from transplanted C2M cells and B-type PGK from recipient mice, and the density of A-type PGK became prominent as the disease progressed. When granulocyte/macrophage progenitor cells of bone marrow cells from leukemic mice were cultured, two types of colonies were observed. By determining PGK types of the colonies, leukemic colonies could be differentiated from normal granulocyte/macrophage colonies. Since C2M cell line has an advantage of processing A-type PGK which can be readily distinguished by the electrophoresis from normal cells, it will serve as a useful tool to study the interaction between leukemic cells and normal hematopoietic cells.

Interstitial deletion of chromosome 2 (p23p25).

We report a patient with a de novo interstitial deletion of the short arm of chromosome 2 (p23p25). The patient had microcephaly with prominent forehead and occiput, narrow rectangular face, clinodactyly, failure to thrive, delayed psychomotor development, and seizures. Maternal serum alpha-fetoprotein was undetectable at 18 weeks of gestation. Heterozygosity at the red cell acid phosphatase locus (SRO-2p25) and normal levels of red cell malate dehydrogenase (SRO-2p23) are findings consistent with the presence of genetic material from bands 2p25 and 2p23.

Deletion of 2p: a cytogenetic and clinical update.

The locus for acid phosphatase (ACP1) had been alternately assigned to two conflicting regions on the short arm of chromosome 2. We present a clinical and cytogenetic report of one patient who has an interstitial deletion of 2, del(2) (p23p25.1), and a cytogenetic study of another cell line with an interstitial deletion of 2p (p23.1p25.1). Because both patients are heterozygotes for ACP1, the assignment of ACP1 to 2p25.1----pter is supported.

Identification of a deletion in the adenosine deaminase gene in a child with severe combined immunodeficiency.

A patient with adenosine deaminase-deficient severe combined immunodeficiency is described whose defect is secondary to deletion of a portion of the ADA structural gene. In Southern analyses, DNA from this patient does not hybridize to a genomic probe that includes the 3' end of exon 1. This implies that both his parents are heterozygous for deletions of exon 1 sequences. Consistent with this finding, the patient has no detectable adenosine deaminase mRNA by Northern analysis. This is the first report of a deletion mutation as the cause of adenosine deaminase deficiency.

Reevaluation of cytochrome b and flavin adenine dinucleotide in neutrophils from patients with chronic granulomatous disease and description of a family with probable autosomal recessive inheritance of cytochrome b deficiency.

Chronic granulomatous disease (CGD) is a genetically heterogeneous syndrome characterized by a microbial killing defect of polymorphonuclear leukocytes (PMNs) due to lack of superoxide O2-. 2 generation. Recent studies indicate that the neutrophil O2-.-generating system consists of at least two components, flavoprotein--flavin adenine dinucleotide (FAD)--and cytochrome b. We evaluate the cytochrome b and FAD content in PMN from 30 CGD patients. The method for quantitating cytochrome b was modified by using PMN sonicates incubated with azide plus hydrogen peroxide. With this approach, several absorption peaks corresponding to myeloperoxidase and eosinophil peroxidase, which overlap with peaks of cytochrome b, were obliterated from reduced-minus-oxidized spectra, whereas the peaks of cytochrome b were not and could be readily quantitated. Cytochrome b was detected in PMNs from all 24 normal adults (47.4 +/- 2.9 pmol/7.5 X 10(6) cells), was absent in PMNs from 11 male CGD patients and one female CGD patient but was present in normal amounts in PMNs from nine male and nine female CGD patients. Stimulated nitroblue tetrazolium (NBT) tests performed on PMNs from mothers of CGD patients indicated that cytochrome b deficiency was associated with X-linked inheritance, except in one case in which probable autosomal recessive inheritance was demonstrated. The PMN NBT test of the mother of another male patient without cytochrome b deficiency suggested an X-linked form of inheritance. In related studies, the FAD content in PMN particulate fractions was reduced in 4 of 28 CGD patients studied. All four CGD patients with reduced FAD lacked cytochrome b. However, three patients with cytochrome b deficiency had normal FAD. Thus, the results indicate that PMN cytochrome b deficiency is observed in most X-linked and in some autosomal recessive CGD, that cytochrome b deficiency may be associated with FAD deficiency, and that cytochrome b and FAD are normal in most patients with non-X-linked CGD.

[Decrease of various enzyme activities in the amniotic fluid of the fetuses with chromosomal anomalies]. / Diminution de certaines activités enzymatiques dans le liquide amniotique de foetus porteurs d'anomalies chromosomiques.

The enzymatic activities of gamma-glutamyl-transpeptidase and of aminopeptidase M have been determined in amniotic fluids taken in pregnancies with a trisomic conceptus. The low values obtained in these fluids may be the consequence of fetal growth retardation.

[A case of 49 XXXXY gonadosomatic dysgenesis: clinical elements and biological consequences of polysomy X]. / A propos d'un cas de dysgénésie gonadosomatique 49 XXXXY: eléments cliniques et conséquences biologiques de la polysomie X.

Discovery of 49 XXXXY syndrome in a six years young boy allows description of the main clinical characteristics of this disease: hypotrophy, facial anomalies, hypogenitalism, delayed speech development and oligophrenia. Radio-cubital synostosis is quite specific in this syndrome. The hypothesis of a correlation between clinical anomalies and excess of genes induced by polysomia has been suggested. We give results of five X-linked enzymatic activities: steroid sulfatase (STS) (located on the probably noninactivated segment), Hypoxanthine Guanine Phosphoribosyl Transferase (HGPRT), Glucose 6 Phosphate Déshydrogenase (G6PD), Phospho Glycerate Kinase (PGK), Alpha Galactosidase A (Alpha GAL A). Only STS activity seems to be significatively increased.

Aniridia: enzyme studies in an 11p--chromosomal deletion.

A patient with aniridia and an interstitial deletion of the bands p13-p14 of the short arm of chromosome 11 was studied to determine the relative locations of the gene(s) encoding for the aniridia-Wilms' tumor association with other genes on the same chromosome. Quantitative analysis was performed on the red blood cell enzymes lactic acid dehydrogenase-A (LDH-A) and catalase, the genes for which are located on the short arm of chromosome 11. The activity of LDH-A was normal; the activity of catalase was reduced to approximately half normal. This evidence supports loci for the genes encoding for both catalase and the aniridia-Wilms' tumor association within the bands p13-p14 of the short arm of chromosome 11; the normal activity of LDH-A supports a locus outside this region.

Three new cases of partial monosomy 21 resulting from one ring 21 chromosome and two unbalanced reciprocal translocations.

Three patients with partial monosomy of the long arm of chromosome 21 are reported. Each one presents several features of a 21q--syndrome but in cases 2 and 3, other chromosomes are involved, contributing to the variability of the clinical picture. Synthesis of clinical, enzymatic and cytogenetic findings confirms that the superoxide dismutase A (SOD-A) locus is in sub-band 21q22-1. However, it is not possible to localize precisely the segments responsible for the different clinical features of 21q--syndrome.