Localization of an ataxia-telangiectasia gene to an approximately 500-kb interval on chromosome 11q23.1: linkage analysis of 176 families by an international consortium

We describe a 20-point linkage analysis map of chromosome 11q22-23 that is based on genotyping 249 families (59 CEPH and 190 A-T). Monte Carlo linkage analyses of 176 ataxia-telangiectasia (A-T) families localizes the major A-T locus to the region between S1819(A4) and S1818(A2). When seven nonlinking families were excluded from subsequent analyses, a 2-lod support interval of approximately 500 kb was identified between S1819(A4) and S1294. No recombinants were observed between A-T and markers S384, B7, S535, or S1294. Only 17 of the international consortium families have been assigned to complementation groups. The available evidence favors either a cluster of A-T genes on chromosome 11 or intragenic defects in a single gene.

A single ataxia telangiectasia gene with a product similar to PI-3 kinase

A gene, ATM, that is mutated in the autosomal recessive disorder ataxia telangiectasia (AT) was identified by positional cloning on chromosome 11q22-23. AT is characterized by cerebellar degeneration, immunodeficiency, chromosomal instability, cancer predisposition, radiation sensitivity, and cell cycle abnormalities. The disease is genetically heterogeneous, with four complementation groups that have been suspected to represent different genes. ATM, which has a transcript of 12 kilobases, was found to be mutated in AT patients from all complementation groups, indicating that it is probably the sole gene responsible for this disorder. A partial ATM complementary DNA clone of 5.9 kilobases encoded a putative protein that is similar to several yeast and mammalian phosphatidylinositol-3' kinases that are involved in mitogenic signal transduction, meiotic recombination, and cell cycle control. The discovery of ATM should enhance understanding of AT and related syndromes and may allow the identification of AT heterozygotes, who are at increased risk of cancer.

Genetic haplotyping of ataxia-telangiectasia families localizes the major gene to an approximately 850 kb region on chromosome 11q23.1

The genotyping data given localize the major A-T gene to an approximately 850 kb region. They also localize the group A A-T gene (ATA) to a region that contains the approximately 850 kb region. They are compatible with linking A-TFresno to 11q22-23. NBS-V2 does not link to this region. Four non-linking families contain only single affecteds, suggesting that these may be spontaneous mutations rather than evidence for an A-T gene outside the 11q22-23 region. Finally, two other non-linking families contain recombinant haplotypes that are compatible with a second A-T gene at 11q22-23, slightly distal to the approximately 850 kb region. However, convincing evidence for a second gene is still lacking.

Ataxia-telangiectasia in Italy: genetic analysis

Genetic analysis was performed on 72 Italian A-T families ascertained through 91 probands. The frequency of the A-T gene was estimated through Dahlberg's formula, which uses the frequencies of first cousin marriages among the patients' parents and in the general population were obtained from the collection of Catholic Church dispensations for the period 1910-1964. Accurate estimates of the disease frequency were made by subdividing data into 5-year periods and between provinces, in order to take into account temporal (decrease over time) and spatial (higher frequency in Southern Italy) heterogeneity. The estimate of the gene frequency for the whole sample was q = 0.012 +/- 0.0065, corresponding to a heterozygote frequency of 2.34% and to a disease frequency of 1 in 7090. When considering q before and after 1970, there was an apparent increase of heterozygote frequency from 1.69 to 3.43%, perhaps due to a better ascertainment of the disease in the latter period. A segregation ratio of 0.249 +/- 0.043 was obtained by analyzing the offspring of the 72 families under the model of incomplete multiple selection. This value is not significantly different from 0.25, as expected for an autosomal recessive disease.

Genetic haplotyping of ataxia-telangiectasia families localizes the major gene to an approximately 850 kb region on chromosome 11q23.1

The genotyping data given localize the major A-T gene to an approximately 850 kb region. They also localize the group A A-T gene (ATA) to a region that contains the approximately 850 kb region. They are compatible with linking A-TFresno to 11q22-23. NBS-V2 does not link to this region. Four non-linking families contain only single affecteds, suggesting that these may be spontaneous mutations rather than evidence for an A-T gene outside the 11q22-23 region. Finally, two other non-linking families contain recombinant haplotypes that are compatible with a second A-T gene at 11q22-23, slightly distal to the approximately 850 kb region. However, convincing evidence for a second gene is still lacking.

Biologic Charachterization of Pleural Metastases from Lung Adenocarcinoma: Description of the New DV90 Cell Line

Aims and background

The characterization of pleural metastases from lung adenocarcinoma is often limited to single biologic features.

Methods

The present paper describes the cellular kinetic parameters, as well as immunocytochemical, ultrastructural and genetic characteristics of the new DV90 cell line, established from the pleural effusion of a stage IV lung adenocarcinoma.

Results

The cell line has a diploid DNA content, a doubling time of 24 h and 7% cloning efficiency, it is tumorigenic in nude mice. Ultrastructural investigation revealed the typical features of lung adenocarcinoma; the diagnosis was confirmed by its immunohistochemical reactivity with a panel of monoclonal antibodies specifically capable of identifying adenocarcinoma cells. Genetic analysis revealed a 46 X, –Y, +8, der (6)t(6?)(q27;?) karyotype and hyperexpression of the protein codified by genes Her2/Neu and p53.

Conclusion

The importance of multidisciplinary biologic characterization in identifying the origin and biological behavior of pleural metastases deriving from lung adenocarcinoma is discussed.

Ataxia-telangiectasia: flow cytometric cell-cycle analysis of lymphoblastoid cell lines in G2/M before and after gamma-irradiation

It has been estimated that 1 to 3% of the general population may be ataxia-telangiectasia (A-T) heterozygotes and hypersensitive to conventional doses of radiation. We attempted to identify heterozygotes by evaluating the proportion of cells in various phases of the cell cycle in response to irradiation. This was accomplished by using flow cytometry to study lymphoblastoid cell lines (LCLs) from 14 A-T homozygotes, 17 genotypic A-T heterozygotes, and 18 normal individuals, including 10 genotypic normals. The LCLs were exposed to 2-gRay radiation and were analyzed after 24 hr along with nonirradiated controls. The difference between the percentage of cells in G2/M with and without irradiation after 24 hr ranged, respectively, from: 12.0 to 31.5% (mean = 18.7 +/- 5.5) for A-T homozygotes; 6.7 to 19.3% (mean = 12.5 +/- 3.8) for A-T heterozygotes; and -1.5 to 12.4% (mean = 6.4 +/- 3.2) for normals. A cut-off region of 9.6 to 13.2% defined by one standard deviation above the mean for normals and one standard deviation below the mean for A-T homozygotes served as the grey zone between normals and A-T heterozygotes or homozygotes. Two of the 18 normals overlapped with the grey zone. Four of 17 heterozygotes were within the normal range; seven fell within the grey zone. This may reflect nongenetic variables, such as the status of the LCLs at the time of testing. Flow cytometry cell-cycle analysis on irradiated LCLs is a useful adjunctive test for establishing a diagnosis of A-T in questionable cases.(ABSTRACT TRUNCATED AT 250 WORDS)

Radiosensitivity of ataxia-telangiectasia, X-linked agammaglobulinemia, and related syndromes using a modified colony survival assay

We used a modified colony survival assay to measure the sensitivity to ionizing radiation of more than 50 lymphoblastoid cell lines from normal individuals and from patients with ataxia-telangiectasia, Nijmegen breakage syndrome variants, and X-linked agammaglobulinemia. All of these disorders are associated with an increased frequency of cancer. Lymphoblastoid cell lines from patients with ataxia-telangiectasia complementation groups A, C, D, and E; ATFresno; Nijmegen breakage syndrome variants V1 and V2; and X-linked agammaglobulinemia showed marked radiosensitivity, whereas ataxia-telangiectasia heterozygotes were similar to controls. Friedreich's ataxia is not associated with increased cancer risk; lymphoblastoid cell lines from two such patients showed normal radiosensitivity. Taken together, these results suggest that some forms of X-ray sensitivity and cancer susceptibility share a common mechanism, such as an enzyme that is necessary both for the repair of radiation damage to DNA and for gene rearrangements during V(D)J recombination.

Norman-Roberts syndrome: clinical and molecular studies

We report on a 7-year-old boy with microcephaly, bitemporal hollowing, low sloping forehead, slightly prominent occiput, widely set eyes, broad and prominent nasal bridge, and severe postnatal growth deficiency. Hypertonia, hyperreflexia, seizures, and profound mental retardation were also present. Brain MRI documented partial agyric cortex with patchy pachygyria, colpocephaly, and hypoplasia of corpus callosum and brain stem, which is consistent with the diagnosis of lissencephaly type I grade 2. On the basis of his phenotypic appearance the patient is considered to have the Norman-Roberts syndrome. Molecular studies, performed by means of in situ hybridization and DNA probe analysis, did not demonstrate deletion in the Miller-Dieker/isolated Lissencephaly critical region on the short arm of chromosome 17.

Neurological and cytogenetic study in early-onset ataxia-telangiectasia patients

The clinical diagnosis of ataxia-telangiectasia (AT) is difficult before the age of 4 years. We report clinical and cytogenetic data on three early-onset, early-diagnosed AT patients at the age of 12, 18 and 22 months, respectively. Postural instability of the trunk, characterized by motor impersistence, was the earliest neurological sign detected as early as 1 year of life. Dystonic movements and postures of arms and trunk and a subtle disorder of eye movement (blinking before gaze changing, increased latency and dysmetry of saccades) were observed during the 2nd year of life. All patients exhibited an unusual temper tantrum. We also observed an increased bleomycin-induced chromosomal instability in patient's cells in the early stages of the disease before all the clinical hallmarks were apparent. Our data suggest that detection of clinical indications, leading to early laboratory confirmation of AT, can reduce the age at diagnosis.

Malignant pleural mesothelioma. Multivariate analysis of prognostic factors on 113 patients

We report on clinical features of 113 cases of pathologically confirmed Malignant Pleural Mesothelioma, observed in Genoa (Italy) between 1979 and 1985. Overall median survival was 10 months. Among the pretreatment variables studied (age, sex, asbestos exposure, pathological type, chest pain and dyspnea at the time of diagnosis), the only one of prognostic value in the univariate analysis was the histological subtype: median survivals were 12, 7 and 4 months for the patients in the epithelial, mixed, and fibrosarcomatous groups, respectively (p = 0.0012). A multivariate analysis confirmed the independent predictive power of the histotype (p = 0.0022). A review of literature data concerning prognostic factors in Malignant Pleural Mesothelioma is presented.

[True hermaphroditism: description of a case]

An infant with normal male external genitalia and preoperative diagnosis of right hydrocele and left cryptorchidism got operative diagnosis of true hermaphroditism. Left ovary and Fallopian tube were removed. Karyotype was 46.XX/47.XXY. The results of the genetic study are shown.

Gelastic epilepsy. A clinical contribution

Gelastic (laughing) epilepsy, relatively uncommon, is usually associated with hypothalamic hamartomas, pituitary tumors, astrocytomas of the mammillary bodies, and dysraphic conditions. Cases of unknown etiology are rare. In three of the four cases reported here, the diagnoses were hamartoma of the tuber cinereum; lobar holoprosencephaly; and lissencephaly type I, grade 2. In the fourth, radiographic investigation gave a normal result; a genetic etiology was suggested because of bilateral familial idiopathic epilepsy. In all patients, EEGs showed both focal spikes and generalized spike-and-wave discharges. The primary underlying neurophysiologic disorder may be provoked by the diffuse hyperexcitability of the cortex and subsequent firing of the thalamocortical networks with which the cortical brain is reciprocally interlinked.

Heterogeneity in ataxia-telangiectasia: classical phenotype associated with intermediate cellular radiosensitivity

We identified a subgroup of ataxia-telangiectasia (AT) patients (2 sibs and 1 unrelated case) characterized by typical clinical manifestations of the disease and cellular radiosensitivity intermediate between classical AT and normal subjects. Our data and a literature review of the intermediate radiosensitivity AT cases show that radioresistant DNA synthesis, cellular radiosensitivity (measured in terms of survival and chromosome breakage), and the clinical hallmarks behave independently. This raises a number of interesting questions about the correlation between radiobiological and clinical features, and about the nature of the AT gene(s).

Epidemiology of infection with HIV-1 in Sardinia: a multicentre prospective study

To study the spread of human immunodeficiency virus type 1 (HIV-1) in Sardinia, we conducted a multicentre prospective study of the prevalence of antibody to HIV-1 (anti-HIV-1) in various populations during 1985-1989. The highest anti-HIV-1 prevalence (61.4%) was found in intravenous drug users. Anti-HIV-1 was found in 32% of haemophiliacs, 4.2% of thalassemics and less than 1% in the other groups. We conclude that control of HIV infection in Sardinia will require a major expansion of prevention and treatment programs for drug addiction.

Localization of an ataxia-telangiectasia locus to a 3-cM interval on chromosome 11q23: linkage analysis of 111 families by an international consortium

Linkage of at least two complementation groups of ataxia-telangiectasia (AT) to the chromosomal region 11q23 is now well established. We provide here an 18-point map of the surrounding genomic region, derived from linkage analysis of 40 CEPH families. On the basis of this map, 111 AT families from Turkey, Israel, England, Italy, and the United States were analyzed, localizing the AT gene(s) to an 8-cM sex-averaged interval between the markers STMY and D11S132/NCAM. A new Monte Carlo method for computing approximate location scores estimates this location as being at least 10(8) times more likely than the next most likely interval, with a support interval midway between STMY and D11S132 that is either 5.2 cM (sex-averaged and conservatively based on 3 lod scores from the maximum-location score) or 2.8 cM (male specific, based on a 2.72:1 interval-specific female-to-male distance ratio.

Syndromes associated with simple calvarial and complex craniofacial anomalies

Central nervous system (CNS) development is a complex process of predetermined events that must occur in an ordered sequence to ensure normal ontogenesis. Various critical steps take place in a relatively short time (from the first few days to the first months of gestation). Both genetic and environmental insults may produce morphological defects. Early defects often result in nonviable embryos; later, complex craniofacial anomalies, mainly associated with brain damage, may be observed. The pathogenesis of congenital malformations is heterogeneous; sporadic cases are reported as well as recessive or dominant inheritance and chromosomal aberrations. Some of these syndromes have been identified as contiguous gene syndromes; the role of critical chromosomal regions and homeobox genes is discussed. Furthermore, these conditions present difficulties in regard to early diagnosis, surgical repair, and social impact.

Xeroderma pigmentosum: clonal chromosomal rearrangements in a pre-cancerous skin lesion

In cells from a papulonodular formation of a patient with the clinical and cellular phenotype of the variant form of xeroderma pigmentosum (XP-V), clonal rearrangements involving different chromosomes were observed. This finding confirms the literature data suggesting that multiple non-specific chromosome anomalies are typical of pre-malignant and malignant skin lesions.

The phenotype of partial dup(7q) reconsidered: a report of five new cases

Five unrelated patients with partial trisomy 7q are described. In two of them the duplicated region was 7q21----qter and in the others 7q22----qter, 7q34----qter and 7q35----qter, respectively. Clinical features were compared with those reported in published cases. Karyotype-phenotype correlations showed a relationship between the size of the unbalanced region and the survival, and prenatal and postnatal growth. In contrast, the same proportionality was not demonstrated between the severity of dysmorphic features and the size of the duplicated region. However, cleft palate seemed associated rather characteristically with dup 7q22/31----qter.

A nonneutralizing human IgM monoclonal antibody inhibiting hemagglutination of H3N2 influenza A strains

A mouse-human hybridoma has been produced by fusing human splenocytes from a Cooley's anemia patient with the murine myeloma P3-NS1/1-Ag 4-1. The hybridoma is stable after 18 months and secretes human IgM. The antibody reacts with some H3N2 influenza A strains and detects an epitope that is part of the hemagglutinin antigen, but does not affect virus infectivity.

Chromosome studies in patients with T-CLL chronic lymphocytic leukemia and expansions of granular lymphocytes

Chromosome analyses were carried out in eight patients with lymphoproliferative disorders of mature T and NK cells. Three cases were characterized by an abnormal expansion of granular lymphocytes (GL), one by a lymphoma of GL with leukemic spread, and four by an OKT4-T-CLL. In four patients cytogenetic studies were performed on bone marrow cells; in seven patients peripheral blood lymphocytes were examined by either direct preparations or PHA-stimulated cultures. Six patients displayed a normal karyotype. Two cases belonging to the OKT4-T-CLL group had a chromosome number ranging from 44 to 47, with multiple numerical and structural clonal anomalies. Clonal anomalies could be a feature of patients with the more aggressive clinical course.

Holoprosencephalic disorders. Case report of a semilobar type

A child with microcephaly, facial dysmorphisms, seizures, and congenital cardiopathy is presented. On the basis of skull x-rays, electroencephalogram, transillumination of the head, and computed tomography (CT) scan, the diagnosis of semilobar holoprosencephaly was made. The heterogeneous etiology of the disorder is discussed in order to evaluate the recurrence risk. The usefulness of CT scan for the classification in the different types of holoprosencephaly is stressed.

Mating between two balanced translocation carriers in two unrelated families

Partial trisomy 9p and a 13/14 translocation occurred in the daughter of a t(5;9)(p15;p12) mother and a t(13;14)(p11;q11) father. Two additional offspring displayed a normal karyotype and a translocation trisomy 13 respectively. Two first cousins, selected for chromosome analysis because of a spontaneous abortion, were found to have an identical translocation t(14;21)(p11;q11). Their second pregnancy was monitored by midtrimester amniocentesis and disclosed a balanced fetus. The different zygotic chromosome constitutions and the counselling problems in the marriages between two balanced translocation carriers are discussed.

Partial monosomy for a 21 chromosome. Report of a new case of r(21) and review of the literature

A 21-month-old male infant with 46,XY,r(21) constitution identified by G and R banding is reported. The main clinical features were mental and physical retardation, microcephaly, antimongoloid slant of eyelids, malformed and low set ears. The clinical and cytogenetic findings of previously reported cases of r(21) are reviewed. Clinical resemblance to the eleven cases described in the literature is striking. The assays for superoxide dismutase (SOD-1) activity in the red blood cells from patient and his parents gave normal results. This findings is compatible with the hypothesis that only the segment distal to the SOD-1 locus, i.e. 21q22.2 leads to qter, has been lost during ring formation.

Segregation of an X ring chromosome in two generations

A 45,X/46,X,r(X) mosaicism was found in a mother and daughter. Characterisation of the ring by banding studies showed that breakpoints had occurred at bands Xp13 and Xq27. It is confirmed that women heterozygotes for partial deficiencies of the short arm of an X chromosome are fertile. Although the mother developed secondary amenorrhoea at the age of 29, it is suggested that fertility per se may not be affected by deficiencies of the distal part of Xq.

Increased HK1 activity levels in the red cells of a patient with a de novo trisomy 10p: t(Y;10)(p11;p12)

A male patient with mental retardation and typical clinical features of 10p trisomy syndrome was found to have a duplication of the short arm of chromosome 10 attached to the short arm of the Y chromosome. Quantitative evaluation of nine red cell enzymes showed significantly increased activity levels of HK1 and, to a lesser extent, of PK, PGI, 6PGD, and G6PD. It is suggested that the HK1 locus may be in the 10pter leads to p12 region. The increased levels of HK1 could affect other erythrocyte metabolic pathways slowing down the physiological rate of cellular senescence and result in increased activity levels of other cell-age-dependent enzymes.

Translocation Y/5 resulting in Cri du Chat syndrome

A case of 45,X,del(5)(p14/45,X,t(Y;5)(q11;p14) mosaicism is described. The patient displays the clinical features of the Cri du Chat syndrome, together with gross malformation of the distal left arm. The presence of male sex development is consistent with the location of factor(s) controlling the male sex determination in the paracentromeric area of the Y chromosome.