Isolation and regional mapping of 110 chromosome 22 STSs

As part of a larger effort to create a complete physical map of the human genome, we have developed 110 new STSs specific for human chromosome 22. Clones isolated and sequenced from chromosome 22-enriched libraries provided a source of primers. These STSs were localized to regions of chromosome 22 using a panel of somatic cell hybrids. In building a refined physical map of chromosome 22, this set of STSs should provide a substantial backbone.

Prenatal diagnosis of the derivative chromosome 22 associated with cat eye syndrome by fluorescence in situ hybridization

Cytogenetic studies of cultured amniocytes demonstrated a karyotype of 46,XX/47,XX, +mar. A bisatellited, dicentric, distamycin-DAPI negative, NOR-positive marker was present in 76 per cent of the metaphases examined. Similar markers have been associated with cat eye syndrome (CES). We report on the utilization of fluorescence in situ hybridization (FISH) with a 14/22 alpha-satellite probe and a chromosome 22-specific cosmid for locus D22S9 to determine the origin of the prenatally detected supernumerary marker chromosome. FISH studies demonstrated that the marker is a derivative of chromosome 22 and enabled us to provide the family with additional prognostic information.

Velo-cardio-facial syndrome and DiGeorge sequence with meningomyelocele and deletions of the 22q11 region

Approximately 5% of children with neural tube defects (NTDs) have a congenital heart defect and/or cleft lip and palate. The cause of isolated meningomyelocele, congenital heart defects, or cleft lip and palate has been largely thought to be multifactorial. However, chromosomal, teratogenic, and single gene causes of combinations of NTDs with congenital heart defects and/or cleft lip and palate have been reported. We report on 3 patients with meningomyelocele, congenital heart defects, and 22q11 deletions. Two of the children had the clinical diagnosis of velo-cardio-facial syndrome (VCFS); both also have bifid uvula. The third child had DiGeorge sequence (DGS). The association of NTDs with 22q11 deletions has not been reported previously. An accurate diagnosis of the 22q11 deletion is critical as this micro-deletion and its associated clinical problems is transmitted as an autosomal dominant trait due to the inheritance of the deletion-bearing chromosome. We recommend that all children with NTDs and congenital heart defects, with or without cleft palate, have cytogenetic and molecular studies performed to detect 22q11 deletions.

"CATCH 22" sans cardiac anomaly, thymic hypoplasia, cleft palate, and hypocalcaemia: cAtch 22. A common result of 22q11 deficiency?

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EWS-erg and EWS-Fli1 fusion transcripts in Ewing's sarcoma and primitive neuroectodermal tumors with variant translocations

We have determined the frequency of EWS fusion transcripts in a series of primary Ewing's sarcomas and peripheral primitive neuroectodermal tumors and cells lines. Type 1 and 2 EWS-Fli1 fusions were demonstrated in 8 cell lines and 14 patient samples. Five patients with cytogenetically characterized rearrangements of chromosome 22 that did not involve chromosome 11 were included in these studies. A novel EWS-Fli1 in-frame isoform fusing EWS to exon 8 of Fli1 was isolated from a tumor with a variant t(12;22;22)(q14;p1;q12) translocation. Three in-frame isoforms of a novel hybrid transcript derived from the fusion of EWS with the ETS domain of the human erg gene were identified in patient samples and a cell line with cytogenetically unidentified or cryptic translocations involving chromosomes 21 and 22. Interphase analysis by fluorescent in situ suppression hybridization using two overlapping erg yeast artificial chromosome clones demonstrated disruption of the erg gene on chromosome 21 in a patient sample with monosomy 22. Our results provide new information about the involvement of EWS in small round cell tumors involving exchange of its putative RNA-binding domain with DNA-binding domains derived from different members of the ETS family of transcription factors. These studies emphasize the utility of reverse transcriptase PCR analysis and fluorescent in situ hybridization as additional diagnostic tools for differential diagnosis among small round cell tumors.

Mapping of the human lambda immunoglobulin variable gene subgroup 1

We describe the cloning and mapping of 20 putative members of the IGLV subgroup 1. These gene segments are contained on 26 phage clones which fall into 7 contigs plus one solitary phage. This represents approximately 240 kilobases (kb) of cloned DNA. Like IGLC gene segments, the IGLV gene segments were found to be oriented proximal to distal on the chromosome, indicating IGL somatic rearrangement is by deletion. The gene segments were placed on a long-range map of the IGL locus, which covers at least 800 kb. Clones were further ordered by pulsed field gel electrophoresis analysis of B-cell lines known to produce IGL-containing immunoglobulins. DNA deletions ranged from 120 to 570 kb.

Molecular characterization of the marker chromosome associated with cat eye syndrome

Cat eye syndrome (CES) is associated with a supernumerary bisatellited marker chromosome which is derived from duplicated regions of 22pter-22q11.2. In this study we have used dosage and RFLP analyses on 10 CES patients with marker chromosomes, by using probes to five loci mapped to 22q11.2. The sequences recognized by the probes D22S9, D22S43, and D22S57 are in four copies in all patients, but the sequences at the more distal loci, D22S36 and D22S75, are duplicated only in some individuals. D22S36 is present in three copies in some individuals, and D22S75 is present in two copies in the majority of cases. Only three individuals have a duplication of the most distal locus examined (D22S75), and these individuals have the largest marker chromosomes identified in this study. From the dosage analysis it was found that the marker chromosomes are variable in size and can be asymmetric in nature. There is no obvious correlation between the severity of the phenotype and the size of the duplication. The distal boundary of the CES critical region (D22S36) is proximal to that of DiGeorge syndrome, a contiguous-gene-deletion syndrome of 22q11.2.

Structure, chromosomal localization, and methylation pattern of the human mb-1 gene

The Ag receptor on B lymphocytes is a multimeric complex that is composed of an Ag-specific component, surface Ig, which is noncovalently associated with at least two other proteins, Ig alpha and Ig beta. These are the glycoprotein products of the B lineage-restricted mb-1 and B29 genes and are crucial for the cell surface expression and function of the Ag receptor on B lymphocytes. To better understand the regulation of mb-1, we have cloned and sequenced a 5.7-kb genomic DNA fragment that contained the human gene. The overall structure of human mb-1 is very similar to that of the murine gene, including the number and approximate size of exons. The promoter region lacks a TATA element, but contains two copies of an early B cell factor-binding motif, which previously has been shown to be important for murine mb-1 expression. Other structural features include two nuclear factor-kappa B binding sites at the 5' end of the gene and a long stretch of AG rich-sequence between exons 3 and 4, downstream of an Alu repeat sequence that contains a potential stem-loop structure. The mb-1 gene was localized to chromosome 19q13.2-13.3 by a combination of two methods, PCR amplification of DNA from a somatic cell hybrid-mapping panel and fluorescence in situ hybridization. An examination of the methylation pattern revealed a striking correlation between demethylation in the 5' region of the gene and expression of mb-1. The demethylated HpaII/MspI sites are adjacent to the nuclear factor-kappa B-binding motifs, which suggests a role for this transcription factor in the regulation of human mb-1 gene expression.

Structure, chromosomal localization, and methylation pattern of the human mb-1 gene

The Ag receptor on B lymphocytes is a multimeric complex that is composed of an Ag-specific component, surface Ig, which is noncovalently associated with at least two other proteins, Ig alpha and Ig beta. These are the glycoprotein products of the B lineage-restricted mb-1 and B29 genes and are crucial for the cell surface expression and function of the Ag receptor on B lymphocytes. To better understand the regulation of mb-1, we have cloned and sequenced a 5.7-kb genomic DNA fragment that contained the human gene. The overall structure of human mb-1 is very similar to that of the murine gene, including the number and approximate size of exons. The promoter region lacks a TATA element, but contains two copies of an early B cell factor-binding motif, which previously has been shown to be important for murine mb-1 expression. Other structural features include two nuclear factor-kappa B binding sites at the 5' end of the gene and a long stretch of AG rich-sequence between exons 3 and 4, downstream of an Alu repeat sequence that contains a potential stem-loop structure. The mb-1 gene was localized to chromosome 19q13.2-13.3 by a combination of two methods, PCR amplification of DNA from a somatic cell hybrid-mapping panel and fluorescence in situ hybridization. An examination of the methylation pattern revealed a striking correlation between demethylation in the 5' region of the gene and expression of mb-1. The demethylated HpaII/MspI sites are adjacent to the nuclear factor-kappa B-binding motifs, which suggests a role for this transcription factor in the regulation of human mb-1 gene expression.

Assessment of injury in transplanted and nontransplanted lungs after 6 h of cold storage with glutathione

Single-lung transplantation after 3 h of hypothermic storage produces bilateral lung injury [pulmonary reimplantation response (PRR)]. We hypothesized that glutathione (GSH) hypothermic storage would protect both lungs from PRR for extended preservation times and that differences in injury and protection would be realized between the graft and the nontransplanted lung. Mongrel dogs underwent left single-lung autotransplantation after preservation for 5-6 h in Euro-Collins (EC) solution, EC plus exogenous GSH (EC+GSH), or Viaspan (VIA) at 4 degrees C. Lung injury was measured in both lungs after 1 h of reperfusion. EC dogs demonstrated significant increases in lung edema, lipid peroxidation, and alveolar neutrophil recruitment in the lung graft and to a less extent in the nontransplanted right lung compared with control dogs (P < 0.05). Edema, lipid peroxidation, and alveolar neutrophils were significantly reduced in both lungs from EC+GSH and VIA dogs compared with lungs from EC dogs (P < 0.05). An increase in large-pore permeability was measured in the lung graft from EC dogs compared with all other lungs. Bronchoalveolar lavage fluid lactate dehydrogenase and total protein concentrations were elevated in both lungs from all three groups of tranplanted dogs compared with those of control dogs (P < 0.05). These data suggest that GSH-containing solutions attenuate the PRR after 6 h of ischemic hypothermic storage but that the protection is incomplete. Mechanisms of injury affecting the lung graft during the PRR appear to differ from those affecting the nontransplanted lung.

Assignment of sterol carrier protein X/sterol carrier protein 2 to 1p32 and its exclusion as the causative gene for infantile neuronal ceroid lipofuscinosis

In the positional cloning of a disease gene with an unknown protein defect a spectrum of molecular biological methods is applied after linkage has been established. It is reasonable to analyze in detail any relevant candidate gene mapping to the particular chromosomal region. We report here the refined chromosomal assignment of SCPx/SCP2, a gene coding for the protein that is believed to have an important role in lipid metabolism by transporting many kinds of lipid molecules between organelles. This gene represents an excellent candidate gene for infantile neuronal ceroid lipofuscinosis, earlier assigned to 1p32 by us, since lipid metabolism in the patient's brain appears to be significantly disturbed. Expression and structural analyses by Northern, Southern and Western blotting as well as SSCP and direct sequencing did not detect any differences between the cDNAs of patients and controls. Consequently, it is unlikely that a mutation in SCPx/SCP2 is the underlying cause of this severe neurodegenerative disease of childhood.

Abnormalities of chromosome 22 in pediatric meningiomas

Cytogenetic studies of eight meningiomas in young children or adolescents were performed. Two tumors exhibited normal karyotypes. Two tumors from patients with bilateral acoustic neurofibromatosis demonstrated monosomy 22 as the only abnormality. Four patients had more complicated karyotypes in which one or both of the chromosomes 22 were missing or structurally altered. The most common secondary changes in these four tumors involved monosomy or structural abnormalities of chromosome 6. These findings confirm that the primary cytogenetic changes in meningioma are similar in children and adults. Molecular analyses of pediatric meningiomas with deletions or translocations of chromosome 22 will be useful for identifying the role of chromosome 22 tumor suppressor genes in this disease.

DiGeorge anomaly with renal agenesis in infants of mothers with diabetes

We report on 2 infants with the DiGeorge anomaly born to diabetic mothers treated with insulin. Both infants had unilateral renal agenesis. One of the mothers has manifestations suggestive of velo-cardio-facial syndrome (VCFS). Cytogenetic studies on both patients and the mother with apparent VCFS were normal. Molecular studies utilizing probes from the DiGeorge critical region did not demonstrate a 22q11 microdeletion in either patient or the mother with apparent VCFS. We conclude that maternal diabetes is a pathogenetic factor in the DiGeorge anomaly, and infants of diabetic mothers who have this anomaly should also be screened for renal agenesis.

Fusion of a fork head domain gene to PAX3 in the solid tumour alveolar rhabdomyosarcoma

We have examined the structure and expression of the products associated with the t(2;13)(q35;q14) translocation associated with alveolar rhabdomyosarcoma. The chromosome 13 gene (FKHR) is identified as a member of the fork head domain family of transcription factors characterized by a conserved DNA binding motif. Polymerase chain reaction analysis demonstrates that a 5'PAX3-3' FKHR chimaeric transcript is expressed in all eight alveolar rhabdomyosarcomas investigated. Immunoprecipitation experiments detect the predicted fusion protein. These findings indicate that the t(2;13) generates a potentially tumorigenic fusion transcription factor consisting of intact PAX3 DNA binding domains, a truncated fork head DNA binding domain and C-terminal FKHR regions.

Long-range restriction map of human chromosome 22q11-22q12 between the lambda immunoglobulin locus and the Ewing sarcoma breakpoint

A long-range restriction map of the region between the immunoglobulin lambda locus and the Ewing sarcoma breakpoint has been constructed using the rare-cutting enzymes NotI, NruI, AscI, and BsiWI. The map spans approximately 11,000 kb and represents about one-fifth of the long arm of chromosome 22. Thirty-nine markers, including seven NotI junction clones as well as numerous genes and anonymous sequences, were mapped to the region with a somatic cell hybrid panel. These probes were then used to produce the map. The seven NotI junction clones each identified a possible CpG island. The breakpoints of the RAJ5 hybrid and the Ewing sarcoma t(11;22) were also localized in the resulting map. This physical map will be useful in studying chromosomal rearrangements in the region, as well as providing the details to examine the fidelity of the YAC and cosmid contigs currently under construction. Comparisons of this physical map to genetic and radiation hybrid maps are discussed.

Velo-cardio-facial syndrome. Intrafamilial variability of the phenotype

We describe a mother and son with velo-cardio-facial syndrome (VCFS) in whom cytogenetic and DNA molecular studies demonstrate an interstitial deletion of the long arm of chromosome 22. Although these two individuals manifest the typical facial and cognitive features of VCFS, they are discordant for the cardiovascular and palatal anomalies, which are seminal manifestations of the disorder. Previously, this degree of phenotypic variability had not been well appreciated within a single family segregating the VCFS deletion. A review of other familial cases of VCFS suggests that the family described in this article is not atypical. Because a microdeletion would be expected to be inherited without alteration within individual families, the phenotypic variability observed in these families appears to be an intrinsic quality of the syndrome and not wholly due to genetic heterogeneity.

A microsatellite-based multipoint index map of human chromosome 22

Utilizing the CEPH (Centre d'Etude du Polymorphism Humain) reference panel and genotyping data for 24 simple tandem repeat polymorphism (STRP) markers, we have constructed a 15-locus multipoint genetic framework map of human chromosome 22. The markers form a continuous linkage group of 51 cM in males and 81 cM in females. Likely genetic locations are provided for 9 additional STRP sequences. The map was constructed employing the CRIMAP computational methodology to build the multipoint map via a stepwise algorithm. The quality of the framework map was evaluated using a battery of statistical diagnostics that suggest a typing error frequency of 0.1% for markers within the map.

Microdeletions of chromosomal region 22q11 in patients with congenital conotruncal cardiac defects

Congenital conotruncal cardiac defects occur with increased frequency in patients with DiGeorge syndrome (DGS). Previous studies have shown that the majority of patients with DGS or velocardiofacial syndrome (VCFS) have a microdeletion within chromosomal region 22q11. We hypothesised that patients with conotruncal defects who were not diagnosed with DGS or VCFS would also have 22q11 deletions. Seventeen non-syndromic patients with one of three types of conotruncal defects most commonly seen in DGS or VCFS were evaluated for a 22q11 deletion. DNA probes from within the DiGeorge critical region were used. Heterozygosity at a locus was assessed using restriction fragment length polymorphisms. Copy number was determined by dosage analysis using Southern blot analysis of fluorescence in situ hybridisation of metaphase spreads. Five of 17 patients were shown to have a 22q11 deletion when evaluated by dosage analysis. This study shows a genetic contribution to the development of some conotruncal cardiac malformations and alters knowledge regarding the risk of heritability of these defects in certain cases.

Prevalence of 22q11 microdeletions in DiGeorge and velocardiofacial syndromes: implications for genetic counselling and prenatal diagnosis

Deletions of chromosome 22q11 have been seen in association with DiGeorge syndrome (DGS) and velocardiofacial syndrome (VCFS). In the present study, we analysed samples from 76 patients referred with a diagnosis of either DGS or VCFS to determine the prevalence of 22q11 deletions in these disorders. Using probes and cosmids from the DiGeorge critical region (DGCR), deletions of 22q11 were detected in 83% of DGS and 68% of VCFS patients by DNA dosage analysis, fluorescence in situ hybridisation, or by both methods. Combined with our previously reported patients, deletions have been detected in 88% of DGS and 76% of VCFS patients. The results of prenatal testing for 22q11 deletions by FISH in two pregnancies are presented. We conclude that FISH is an efficient and direct method for the detection of 22q11 deletions in subjects with features of DGS and VCFS as well as in pregnancies at high risk for a deletion.

A panel of sequence tagged sites for chromosome band 11q23

A panel of sequence tagged sites (STSs) representing 30 markers previously assigned to human chromosome band 11q23 has been assembled. Eleven STSs represent cloned genes, and the remainder are from anonymous DNA segments. The STSs have been used in PCR experiments to localize their cognate sequences further with respect to five translocation breakpoints that define three intervals in 11q23. Two of these translocation breakpoints have been mapped more precisely by the STS assignments. The STS panel will form a useful starting point for the generation of a genomic contig of band 11q23.

Comparative mapping of 9 human chromosome 22q loci in the laboratory mouse

We present a comparative map of genes on human chromosome 22q and homologous loci in the mouse genome. Gene order in humans was established using a panel of somatic cell hybrids. Genetic maps spanning homologous segments on three mouse chromosomes were generated using an interspecific backcross. The conserved linkage between human chromosome 22 and mouse chromosome 16 includes two closely linked loci, Comt and IgI-1. The second conserved linkage involves human chromosome 22 and mouse chromosome 11 and contains two genetically and physically linked loci, Lif and Nfh. Finally, conserved synteny involving mouse chromosome 15 and human chromosome 22 spans 30 cM and contains five loci (Acr, Bzrp, Dia-1, Il2rb and Pdgfb). Loci within this conserved synteny have been sublocalized to different portions of human chromosome 22. The order of genes on mouse chromosome 15 and human chromosome 22 provides further evidence for chromosomal rearrangements within the conserved synteny that have occurred since the divergence of lineages leading to mice and humans.

Malaria in children in Chicago

OBJECTIVE

To review the experience of a large children's hospital and two community hospitals in Chicago in which malaria was diagnosed in children during a recent 6-year period.

METHODS

Retrospective medical record review covering the years 1985 to 1990.

RESULTS

Twenty cases of childhood malaria were diagnosed, generally in patients hospitalized for fever unresponsive to oral antibiotics also associated with splenomegaly, with presumptive diagnoses of malignancy, typhoid fever, acute appendicitis, or urinary tract infection. History of recent immigration to the United States or travel to a malaria-endemic area was frequently not elicited until several days into hospitalization, thus delaying diagnosis and therapy.

CONCLUSIONS

Because malaria in the United States pediatric population has increased as a result of foreign immigration and overseas travel, pediatricians must be alert to the possibility of malaria in febrile children, and the importance of antimalarial prophylaxis should be communicated to parents of children traveling to endemic areas.

Allopurinol inhibition of neutrophilic alveolar response during hyperoxia

Allopurinol is a potent xanthine oxidase inhibitor that has been administered to animals to protect tissues from oxidant injury. We hypothesized that allopurinol may protect against oxidant injury by inhibiting the inflammatory response. Male Sprague-Dawley rats were injected daily with vehicle or allopurinol and compared with noninjected controls. Animals were exposed to room air or 90% oxygen for 14 days. At the end of the exposure period, all animals were lavaged and bronchoalveolar lavage fluid (BALF) was examined for cell counts, lactate dehydrogenase (LDH), and protein. BALF neutrophils were significantly increased in oxygen-exposed noninjected controls (33 +/- 7 x 10(3)/mm3) and also in the vehicle-inoculated oxygen-exposed animals (43 +/- 6 x 10(3)/mm3). Allopurinol treatment resulted in a decrease in the neutrophilic alveolar response in oxygen-exposed animals (5.3 +/- 4 x 10(3)/mm3, P < 0.001). These data reveal that oxygen exposure produces a neutrophilic alveolar response that is attenuated by allopurinol treatment. BALF protein and LDH were significantly increased in all inoculated and noninoculated oxygen-exposed animals compared with air-exposed animals. Therefore, allopurinol decreases the neutrophilic alveolar response produced by a hyperoxic exposure in the rat but does not decrease lung injury as assessed by alveolar LDH and protein release.

A set of STS assays targeting the chromosome 22 physical framework markers

The widespread use of the sequence-tagged site (STS) as a quick, efficient, and reproducible assay for comparing physical and genetic map information promises to facilitate greatly long-range goals of the mapping of the human genome. We have designed 21 STS assays for loci on human chromosome 22. These assays primarily tag the physical framework markers of the long arm of 22, but additional assays have been designed from known genes and loci in the neurofibromatosis 2 (NF2) region. The availability of these assays will make these loci available to the research community without physical transfer of materials and will serve as start points for further efforts to physically map chromosome 22 with yeast artificial chromosome clones.