High prevalence of comorbidities and use of concomitant medication in treated people living with HIV in Germany - results of the BESIDE study

Due to demographic changes in people living with HIV (PLHIV), physicians are challenged with age-related comorbidities and their management. In the absence of comprehensive data collection, the burden of comorbidities and co-medication in addition to antiretroviral therapy (ART) remains unclear for the German real-world setting. BESIDE was an observational, cross-sectional study evaluating the prevalence of comorbidities and use of co-medication in treated PLHIV. Regional distribution of study centers (n = 20), consecutive patient recruitment, and age-stratified sampling in alignment with national epidemiologic data aimed to ensure a representative sample (n = 453). The overall prevalence of comorbidities was 91.2%; 31.6% of patients had ≥4 comorbidities. The most common diagnoses were vitamin D deficiency (29.1%), depressive episode (27.8%), arterial hypertension (16.3%), and hypercholesterolemia (10.8%). 83.7% of patients were on co-medication; 21.2% taking ≥4 medications. The most common medications or supplements were vitamins (31.6%), anti-inflammatory agents (16.1%), renin-angiotensin system agents (12.1%), acid suppressants (11.7%), lipid modifying agents (10.8%); 1.3% of patients were on co-medication that should not be co-administered with ART, 41.5% on co-medication with potential for drug-drug interactions. The prevalence of comorbidities and use of co-medication among treated PLHIV in Germany is consistently high and increases across age groups, illustrating the complexity of HIV care involving appropriate ART selection.

High prevalence of recreational and illicit drug use in German people living with HIV with a potential for drug-drug interactions with antiretroviral therapy

Recreational drug use is higher in people living with HIV (PLHIV) than in the general population in Europe. This use increases the risk for drug-drug interactions (DDIs) and adverse events. We assessed the prevalence and clinical consequences of substance abuse among PLHIV. BESIDE was a cross-sectional, multi-center study in 2016/18, evaluating comorbidities, polypharmacy and recreational/illicit drug use in PLHIV on antiretroviral therapy (ART) in Germany. Legal and illicit drug use was recorded using two anonymous patient questionnaires one year apart (Q1 and Q2). The BESIDE study population consisted of 453 PLHIV (22% female, median age 46 years). Recreational drug use was reported by the majority (Q1: ever used 73%, within previous 6 months 56%): nitrite inhalants ("poppers"), cannabis and PDE-5 inhibitors were common across all age groups; ecstasy, (meth-)amphetamine and gamma-hydroxybutyrate/gamma-butyrolactone were predominantly reported by younger PLHIV. Based on Q2, two-thirds of PLHIV (67%) had been informed about potential risks of drug abuse by their doctors, whereas one-third (33%) had talked to their doctors on their own initiative with only 7% considering drug use in combination with ART a problem. Strikingly, 44% and 42% had undergone medical treatment or had been hospitalized due to drug use. These data emphasize the high clinical relevance of recreational drug use in PLHIV and the need for treating physicians to pro-actively communicate the potential risks.

The genetic architecture of left ventricular non-compaction reveals both substantial overlap with other cardiomyopathies and a distinct aetiology in a subset of cases

Background

Left ventricular non-compaction (LVNC) is a condition characterised by trabeculations in the myocardial wall and is the subject of considerable conjecture as to whether it represents a distinct pathology or a secondary phenotype associated with other cardiac diseases, particularly cardiomyopathies.

Purpose

To investigate the genetic architecture of LVNC by identifying genes and variant classes robustly associated with disease and comparing these to other genetically characterised cardiomyopathies.

Methods

We performed rare variant association analysis using six different LVNC cohorts comprising 840 cases together with 125,748 gnomAD population controls and compared results to similar analyses with dilated cardiomyopathy (DCM) and hypertrophic cardiomyopathy (HCM) cases.

Results

We observed substantial overlap in genes and variant classes enriched in LVNC and DCM/HCM, indicating that in many cases LVNC belongs to a spectrum of more established cardiomyopathies, with non-compaction representing a phenotypic variation in patients with DCM- or HCM-causing variants. In contrast, five variant classes were uniquely enriched in LVNC cases, of which truncating variants in MYH7, ACTN2 and PRDM16 may represent a distinct LVNC aetiology. MYH7 truncating variants are generally considered as non-pathogenic but were detected in 2% of LVNC cases compared to 0.1% of controls, including a cluster of variants around a single splice region. Additionally, structural variants (exon deletions) in RYR2 and missense variants in the transmembrane region of HCN4 were enriched in LVNC cases, confirming prior reports regarding the association of these variant classes with combined LVNC and arrhythmia phenotypes.

Conclusions

We demonstrated that genetic association analysis can clarify the relationship between LVNC and established cardiomyopathies, highlighted substantial overlap with DCM/HCM but also identified variant classes associated with distinct LVNC and with joint LVNC/arrhythmia phenotypes. These results underline the complex genetic landscape of LVNC and inform how genetic testing in LVNC cases should be pursued and interpreted.

Cardiomyopathy rare variant frequencies

Funding Acknowledgement

Type of funding source: None

4258Re-evaluating the genetic contribution of monogenic dilated cardiomyopathy

Background

Dilated cardiomyopathy (DCM) is genetically heterogeneous, with >100 purported disease genes tested in clinical laboratories. However, many genes were originally identified based on candidate-gene studies that did not adequately account for background population variation. Here we define the frequency of rare variation in 2538 DCM patients across protein-coding regions of 56 commonly tested genes and compare this to both 912 confirmed healthy controls and a reference population of 60,706 individuals.

Purpose

To identify clinically interpretable genes robustly associated with dominant monogenic DCM.

Methods

We used the TruSight Cardio sequencing panel to evaluate the burden of rare variants in 56 putative DCM genes in 1040 DCM patients and 912 healthy volunteers processed with identical sequencing and bioinformatics pipelines. We further aggregated data from 1498 DCM patients sequenced in diagnostic laboratories and the ExAC database for replication and meta-analysis.

Results

Specific variant classes in TTN, DSP, MYH7 and LMNA were associated with DCM in all comparisons. Variants in BAG3, TNNT2, TPM1, NEXN and VCL were significantly enriched specific patient subsets, with the last 3 genes likely contributing primarily to early-onset forms of DCM. Overall, rare variants in these 9 genes potentially explained 19–26% of cases. Whilst the absence of a significant excess in other genes cannot preclude a role in disease, such genes have limited diagnostic value since novel variants will be uninterpretable and therefore non-actionable, and their diagnostic yield is minimal.

Conclusion

In the largest sequenced DCM cohort yet described, we observe robust disease association only with a limited number of genes, highlighting their importance in DCM and translating into high interpretability in diagnostic testing. The other genes evaluated have limited value in diagnostic testing in DCM. This data will contribute to community gene curation efforts, and will reduce erroneous and inconclusive findings in diagnostic testing.

Acknowledgement/Funding

Wellcome Trust (107469/Z/15/Z), BHF (SP/10/10/28431), MRC (MR/M003191/1), Fondation Leducq (11-CVD01), Italian Ministry of Health (RF-2013-02356787)

Cross-sectional increase of adherence to multidisciplinary tumor board decisions

BACKGROUND

Cancer research has made great progress in the recent years. With the increasing number of options in diagnosis and therapy the implementation of tumorboards (TUBs) has become standard procedure in the treatment of cancer patients. Adherence tests on tumor board decisions are intended to enable quality assurance and enhancement for work in tumor boards in order to continuously optimize treatment options for cancer patients.

METHODS

Subject of this study was the adherence of the recommendations made in three of 14 tumorboards, which take place weekly in the Center for Integrated Oncology (CIO) at the University Hospital Bonn. In total, therapy recommendations of 3815 patient cases were checked on their implementation. A classification into four groups has been made according to the degree of implementation. A second classification followed regarding the reasons for differences between the recommendation and the therapy which the patient actually received.

RESULTS

The study showed that 80.1% of all recommendations in the three TUBs were implemented. 8.3% of all recommendations showed a deviance. Most important reasons for the deviances were patient wish (36.5%), patient death (26%) and doctoral decision, due to the patient's comorbidities or side effects of the treatment (24.1%).Interestingly, deviance in all three tumor boards in total significantly decreased over time.

CONCLUSIONS

Aim of the study was to clarify the use of tumor boards and find approaches to make them more efficient. Based on the results efficiency might be optimized by increased consideration of patients` preferences, improved presentation of patient-related data, more detailed documentation and further structuring of the tumor board meetings.

Similar efficacy and tolerability of raltegravir-based antiretroviral therapy in HIV-infected patients, irrespective of age group, burden of comorbidities and concomitant medication: Real-life analysis of the German 'WIP' cohort

Only limited efficacy and tolerability data on raltegravir (RAL) use are currently available. Study objectives were to describe the efficacy and tolerability profile of RAL-based antiretroviral therapy (ART) in routine clinical practice in Germany. The WIP study (WIP = “Wirksamkeit von Isentress unter Praxisbedingungen”, Efficacy of Isentress under routine clinical conditions) was a prospective, multi-centre cohort study in Germany. Human immunodeficiency virus (HIV)-infected patients aged ≥ 18 years in whom combinational ART with RAL 400 mg BID was indicated were enrolled. The primary endpoint was virologic response (HIV-RNA <50 copies/mL; non-completion equals failure) after 48 weeks. Of 451 patients, 85.1% (n = 384) were still receiving RAL at week 48. At baseline (BL), the prevalence of concomitant diseases was higher in patients of the age group ≥50 years (94.2% vs. 75.7%) as well as concomitant medications (74.8 % vs. 55.4%). Virologic response at week 48 was 74.7% (overall), 75.0% (naïve at BL), 81.5% (suppressed at BL), 47.1% (interrupted previous treatment at BL) and 64.9% (failing at BL), without significant differences by age group. A significant correlation of achievement of HIV-RNA <50 copies/mL was seen with treatment status at BL (p = 0.004). In addition, 77.3 % of the patients with a CD4 cell count >200 cells/µL at BL achieved HIV-RNA <50 copies/mL (p = 0.029). RAL was well tolerated with 80 adverse events (AEs) in 49 patients (10.9%) and 8 serious AEs (SAEs) in 6 patients (1.3%) reported to be drug related. A total of 22 patients (4.9%) discontinued treatment due to AEs. The WIP study shows that the previously reported efficacy and safety profile of RAL can be achieved in a population with multiple comorbidities and comedications, with no major difference observed in ageing patients (≥50 years) vs. younger patients. RAL is therefore an attractive treatment option in routine medical care in Germany.

Vertical structure of stratospheric water vapour trends derived from merged satellite data

Stratospheric water vapour is a powerful greenhouse gas. The longest available record from balloon observations over Boulder, Colorado, USA shows increases in stratospheric water vapour concentrations that cannot be fully explained by observed changes in the main drivers, tropical tropopause temperatures and methane. Satellite observations could help resolve the issue, but constructing a reliable long-term data record from individual short satellite records is challenging. Here we present an approach to merge satellite data sets with the help of a chemistry-climate model nudged to observed meteorology. We use the models' water vapour as a transfer function between data sets that overcomes issues arising from instrument drift and short overlap periods. In the lower stratosphere, our water vapour record extends back to 1988 and water vapour concentrations largely follow tropical tropopause temperatures. Lower and mid-stratospheric long-term trends are negative, and the trends from Boulder are shown not to be globally representative. In the upper stratosphere, our record extends back to 1986 and shows positive long-term trends. The altitudinal differences in the trends are explained by methane oxidation together with a strengthened lower-stratospheric and a weakened upper-stratospheric circulation inferred by this analysis. Our results call into question previous estimates of surface radiative forcing based on presumed global long-term increases in water vapour concentrations in the lower stratosphere.

Functional characterisation of decoy receptor 3 in Crohn's disease

AIMS

Both epithelial barrier dysfunction and apoptosis resistance of immune cells contribute to the pathogenesis of Crohn's disease. The soluble decoy receptor 3 (DcR3) acts in an anti-apoptotic manner by neutralising the death ligand CD95L. Here, we investigated the possible involvement of DcR3 in Crohn's disease.

METHODS

The epithelial fraction of human small intestinal mucosa samples was obtained by laser microdissection. Expression of DcR3 was examined by global gene expression profiling, quantitative reverse transcription polymerase chain reaction, immunoblot analysis, and immunohistochemistry. DcR3 concentrations in the serum of patients with Crohn's disease were measured by enzyme-linked immunosorbent assay. Apoptosis assays were performed to study the effects of DcR3 in intestinal epithelial cells and lamina propria T cells.

RESULTS

DcR3 is over-expressed in the epithelial layer of ileum specimens in patients with Crohn's disease, both at actively inflamed and non-active sites. DcR3 serum levels are significantly elevated in patients with active and non-active Crohn's disease as compared to healthy controls. The expression of DcR3 in intestinal epithelial cells is induced by tumour necrosis factor alpha. Increased DcR3 expression is associated with activation of nuclear factor kappa B (NF-kappaB) and results in protection of intestinal epithelial cells and lamina propria T cells from CD95L-induced apoptosis.

CONCLUSIONS

DcR3 may promote inflammation in Crohn's disease by inhibiting CD95L-induced apoptosis of epithelial and immune cells as well as by inducing NF-kappaB activation.

Up-regulation of the phosphoinositide 3-kinase pathway in human lamina propria T lymphocytes

Human intestinal lamina propria T lymphocytes (LPT), when investigated ex vivo, exhibit functional properties profoundly different from those of peripheral blood T lymphocytes (PBT). One prominent feature represents their enhanced sensitivity to CD2 stimulation when compared to PBT. Given that LPT are hyporesponsive to T cell receptor (TCR)/CD3 stimulation, an alternative activation mode, as mimicked by CD2 triggering in vitro, may be functional in mucosal inflammation in vivo. This study provides insight into signalling events associated with the high CD2 responsiveness of LPT. When compared to PBT, LPT show an increased activation of the phosphoinositide 3/protein kinase B/glycogen synthase kinase 3beta (PI3-kinase/AKT/GSK-3beta) pathway in response to CD2 stimulation. Evidence is provided that up-regulation of this pathway contributes to the enhanced CD2-induced cytokine production in LPT. Given the importance of TCR-independent stimulation for the initiation of intestinal immune responses analysis of signalling pathways induced by 'co-stimulatory' receptors may provide valuable information for therapeutic drug design.

A novel model of fibroblast-mediated cartilage destruction

In rheumatoid arthritis (RA), fibroblasts have been shown to be crucial for disease progression as well as joint destruction. In the model of human/murine SCID arthritis, synovial explants as well as fibroblasts from human rheumatoid synovial membrane induce destructive arthritis in immunodeficient mice. Hereby, the underlying cartilage destruction is accomplished by murine fibroblasts. Therefore, murine destructive fibroblasts represent a promising tool to investigate destruction of articular cartilage and bone. In this context, a novel destructive murine fibroblast line (LS48) was examined for morphological, ultrastructural, immunological and functional cellular parameters. These cells were injected into knees of SCID mice. Subsequently, the animals were monitored for joint swelling and serological parameters of arthritis by radiological methods. Finally, cartilage destruction was assessed morphologically. Cultured LS48 cells exhibit characteristic features that resemble those of activated synovial fibroblasts in human RA. Expression levels of inducible nitric oxide synthase, interleukin-6, tumour necrosis factor-alpha and matrix metalloproteinases were comparable to those detected in invasive human fibroblasts. The instillation of 5 x 10(5) LS48 cells into the knee joints of SCID mice initiated a rapid progressive process, that caused cartilage destruction within 10 days, and morphological examinations revealed that articular cartilage was infiltrated by the fibroblasts injected previously. In summary, the intra-articular application of LS48 cells represents a rapid and highly reproducible model to investigate the initiation and progression of cartilage destruction in connection with RA therapy and represents an easy-to-handle animal model.

Immunological evaluation of the new stable ultrasound contrast agent LK565: a phase one clinical trial

Background

Ultrasound contrast agents (UCAs) allow the enhancement of vascular definition, thereby providing more diagnostic information. LK565 is a new second-generation UCA based on synthetic polymers of aspartic acid which is eliminated from the blood stream via phagocytosis. LK565 forms very stable air-filled microspheres and is capable of repeated passage through the pulmonary capillary bed after peripheral intravenous injection. This characteristic allows examination of the cardiac function or extracardiac vessel abnormalities up to 15 minutes.

Methods

A phase one clinical study was conducted on 15 healthy volunteers to identify the development of an undesirable immune response. Phagocytosis capacity, TNF-α secretion, and MHC class II upregulation of monocytes was monitored, as well as microsphere specific antibody development (IgM, IgG). Furthermore, the kinetics of the activation surface markers CD69, CD25, CD71, and CD11b on leukocytes were analyzed.

Results

Due to LK565-metabolism the administration of the UCA led to saturation of phagocytes which was reversible after 24 hrs. Compared to positive controls neither significant TNF-α elevation, neither MHC class II and activation surface markers upregulation, nor specific antibody development was detectable.

Conclusion

The administration of LK565 provides a comfortable duration of signal enhancement, esp. in echocardiography, without causing a major activation cascade or triggering an adaptive immune response. To minimize the risk of undesirable adverse events such as anaphylactoid reactions, immunological studies should be included in clinical trials for new UCAs. The use of LK565 as another new ultrasound contrast agent should be encouraged as a safe means to provide additional diagnostic information.

Mice overexpressing genes from the 22q11 region deleted in velo-cardio-facial syndrome/DiGeorge syndrome have middle and inner ear defects

Velo-cardio-facial syndrome/DiGeorge syndrome (VCFS/DGS) is a congenital anomaly disorder associated with hemizygous 22q11 deletions. We previously showed that bacterial artificial chromosome (BAC) transgenic mice overexpressing four transgenes, PNUTL1, (CDCrel-1), GP1B beta, TBX1 and WDR14, had reduced viability, cardiovascular malformations and thymus gland hypoplasia. Since these are hallmark features of VCFS/DGS, we analyzed the mice for additional anomalies. We found that the mice have important defects in the middle and inner ear that are directly relevant to the disorder. The most striking defect was the presence of chronic otitis media, a common finding in VCFS/DGS patients. In addition, the mice had a hyperactive circling behavior and sensorineural hearing loss. This was associated with middle and inner ear malformations, analogous to Mondini dysplasia in humans reported to occur in VCFS/DGS patients. We propose that overexpression of one or more of the transgenes is responsible for the etiology of the ear defects in the mice. Based upon its pattern of expression in the ear and functional studies of the gene, TbX1 likely plays a central role. Haploinsufficiency of TBX1 may be responsible for ear disorders in VCFS/DGS patients.

Isolation and characterization of a novel gene containing WD40 repeats from the region deleted in velo-cardio-facial/DiGeorge syndrome on chromosome 22q11

Three congenital disorders, cat-eye syndrome (CES), der(22) syndrome, and velo-cardio-facial syndrome/DiGeorge syndrome (VCFS/DGS), result from tetrasomy, trisomy, and monosomy, respectively, of part of 22q11. They share a 1.5-Mb region of overlap, which contains 24 known genes. Although the region has been sequenced and extensively analyzed, it is expected to contain additional genes, which have thus far escaped identification. To understand completely the molecular etiology of VCFS/DGS, der(22) syndrome, and CES, it is essential to isolate all genes in the interval. We have identified and characterized a novel human gene, located within the 1.5-Mb region deleted in VCFS/DGS, trisomic in der(22) syndrome and tetrasomic in CES. The deduced amino acid sequence of the human gene and its mouse homologue contain several WD40 repeats, but lack homology to known proteins. We termed this gene WDR14 (WD40 repeat-containing gene deleted in VCFS). It is expressed in a variety of human and mouse adult and fetal tissues with substantial expression levels in the adult thymus, an organ hypoplastic in VCFS/DGS.

TBX1 is responsible for cardiovascular defects in velo-cardio-facial/DiGeorge syndrome

Velo-cardio-facial syndrome (VCFS)/DiGeorge syndrome (DGS) is a human disorder characterized by a number of phenotypic features including cardiovascular defects. Most VCFS/DGS patients are hemizygous for a 1.5-3.0 Mb region of 22q11. To investigate the etiology of this disorder, we used a cre-loxP strategy to generate mice that are hemizygous for a 1.5 Mb deletion corresponding to that on 22q11. These mice exhibit significant perinatal lethality and have conotruncal and parathyroid defects. The conotruncal defects can be partially rescued by a human BAC containing the TBX1 gene. Mice heterozygous for a null mutation in Tbx1 develop conotruncal defects. These results together with the expression patterns of Tbx1 suggest a major role for this gene in the molecular etiology of VCFS/DGS.

Optimized spectral microwindows for data analysis of the Michelson Interferometer for Passive Atmospheric Sounding on the Environmental Satellite

For data analysis of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) atmospheric limb emission spectroscopic experiment on Environmental Satellite microwindows, i.e., small spectral regions for data analysis, have been defined and optimized. A novel optimization scheme has been developed for this purpose that adjusts microwindow boundaries such that the total retrieval error with respect to measurement noise, parameter uncertainties, and systematic errors is minimized. Dedicated databases that contain optimized microwindows for retrieval of vertical profiles of pressure and temperature, H2O, O3, HNO3, CH4, N2O, and NO2 have been generated. Furthermore, a tool for optimal selection of subsets of predefined microwindows for specific retrieval situations has been provided. This tool can be used further for estimating total retrieval errors for a selected microwindow subset. It has been shown by use of this tool that an altitude-dependent definition of microwindows is superior to an altitude-independent definition. For computational efficiency a dedicated microwindow-related list of spectral lines has been defined that contains only those spectral lines that are of relevance for MIPAS limb sounding observations.

Expression of Cdcrel-1 (Pnutl1), a gene frequently deleted in velo-cardio-facial syndrome/DiGeorge syndrome

The murine Cdcrel-1 (Pnutl1) gene belongs to the family of septins, which are thought to be involved in cytokinesis in yeast, Drosophila and vertebrates. Recent studies implicate Cdcrel-1 in the regulation of vesicle transport in neurons of the adult brain. The human homologue, hCDCREL-1 maps to chromosome 22q11.2, a region commonly deleted in patients displaying velo-cardio-facial syndrome (VCFS) or DiGeorge syndrome (DGS). During development, Cdcrel-1 transcripts are expressed from E10.5 on in the nervous system such as the dorsal root ganglia and the cranial ganglia as well as the lateral layer of the neural tube, the area where terminally differentiated neurons are located. Low level expression is found in the mesenchyme of the frontonasal mass and the limb bud mesenchyme of E11.5 and E13.5 murine embryos. At E15.5, expression is detected in the nervous tissue and in the neural layer of the eye. Based on the expression pattern as well as clinical data, Cdcrel-1 may be involved in the etiology of VCFS/DGS.

A common molecular basis for rearrangement disorders on chromosome 22q11

The chromosome 22q11 region is susceptible to rearrangements that are associated with congenital anomaly disorders and malignant tumors. Three congenital anomaly disorders, cat-eye syndrome, der() syndrome and velo-cardio-facial syndrome/DiGeorge syndrome (VCFS/DGS) are associated with tetrasomy, trisomy or monosomy, respectively, for part of chromosome 22q11. VCFS/DGS is the most common syndrome associated with 22q11 rearrangements. In order to determine whether there are particular regions on 22q11 that are prone to rearrangements, the deletion end-points in a large number of VCFS/DGS patients were defined by haplotype analysis. Most VCFS/DGS patients have a similar 3 Mb deletion, some have a nested distal deletion breakpoint resulting in a 1.5 Mb deletion and a few rare patients have unique deletions or translocations. The high prevalence of the disorder in the population and the fact that most cases occur sporadically suggest that sequences at or near the breakpoints confer susceptibility to chromosome rearrangements. To investigate this hypothesis, we developed hamster-human somatic hybrid cell lines from VCFS/DGS patients with all three classes of deletions and we now show that the breakpoints occur within similar low copy repeats, termed LCR22s. To support this idea further, we identified a family that carries an interstitial duplication of the same 3 Mb region that is deleted in VCFS/DGS patients. We present models to explain how the LCR22s can mediate different homologous recombination events, thereby generating a number of rearrangements that are associated with congenital anomaly disorders. We identified five additional copies of the LCR22 on 22q11 that may mediate other rearrangements leading to disease.

Der(22) syndrome and velo-cardio-facial syndrome/DiGeorge syndrome share a 1.5-Mb region of overlap on chromosome 22q11

Derivative 22 (der[22]) syndrome is a rare disorder associated with multiple congenital anomalies, including profound mental retardation, preauricular skin tags or pits, and conotruncal heart defects. It can occur in offspring of carriers of the constitutional t(11;22)(q23;q11) translocation, owing to a 3:1 meiotic malsegregation event resulting in partial trisomy of chromosomes 11 and 22. The trisomic region on chromosome 22 overlaps the region hemizygously deleted in another congenital anomaly disorder, velo-cardio-facial syndrome/DiGeorge syndrome (VCFS/DGS). Most patients with VCFS/DGS have a similar 3-Mb deletion, whereas some have a nested distal deletion endpoint resulting in a 1.5-Mb deletion, and a few rare patients have unique deletions. To define the interval on 22q11 containing the t(11;22) breakpoint, haplotype analysis and FISH mapping were performed for five patients with der(22) syndrome. Analysis of all the patients was consistent with 3:1 meiotic malsegregation in the t(11;22) carrier parent. FISH-mapping studies showed that the t(11;22) breakpoint occurred in the same interval as the 1.5-Mb distal deletion breakpoint for VCFS. The deletion breakpoint of one VCFS patient with an unbalanced t(18;22) translocation also occurred in the same region. Hamster-human somatic hybrid cell lines from a patient with der(22) syndrome and a patient with VCFS showed that the breakpoints occurred in an interval containing low-copy repeats, distal to RANBP1 and proximal to ZNF74. The presence of low-copy repetitive sequences may confer susceptibility to chromosome rearrangements. A 1.5-Mb region of overlap on 22q11 in both syndromes suggests the presence of dosage-dependent genes in this interval.

Isolation and characterization of a human gene containing a nuclear localization signal from the critical region for velo-cardio-facial syndrome on 22q11

Velo-cardio-facial syndrome (VCFS) and DiGeorge syndrome are congenital disorders characterized by craniofacial anomalies, conotruncal heart defects, immune deficiencies, and learning disabilities. Both diseases are associated with similar hemizygous 22q11 deletions, indicating that haploinsufficiency of a gene(s) in 22q11 is responsible for their etiology. We describe here a new gene called NLVCF, which maps to the critical region for VCFS on 22q11 between the genes HIRA and UFD1L. NLVCF encodes a putative protein of 206 amino acids. The coding region encompasses four exons that span a genomic interval of 3.4 kb. Coding sequence analysis revealed that NLVCF is a novel gene that contains two consensus sequences for nuclear localization signals. The Nlvcf mouse homolog is 75% identical in amino acid sequence and maps to the orthologous region on mouse chromosome 16. The human NLVCF transcript is 1.3 kb in size and is expressed at varying levels in many fetal and adult tissues. Whole-mount in situ hybridization showed that Nlvcf is expressed in most structures of 9.5-dpc mouse embryos, with especially high expression in the head as well as in the first and second pharyngeal arches. NLVCF and HIRA are divergently transcribed, and their start codons lie approximately 1 kb apart in both humans and mice. Interestingly, the two genes exhibit a similar expression pattern in mouse embryos, suggesting that they may share common regulatory elements. The pattern of expression of NLVCF and its localization in the critical region suggest that NLVCF may contribute to the etiology of VCFS.

Comparative mapping of the human 22q11 chromosomal region and the orthologous region in mice reveals complex changes in gene organization

The region of human chromosome 22q11 is prone to rearrangements. The resulting chromosomal abnormalities are involved in Velo-cardio-facial and DiGeorge syndromes (VCFS and DGS) (deletions), "cat eye" syndrome (duplications), and certain types of tumors (translocations). As a prelude to the development of mouse models for VCFS/DGS by generating targeted deletions in the mouse genome, we examined the organization of genes from human chromosome 22q11 in the mouse. Using genetic linkage analysis and detailed physical mapping, we show that genes from a relatively small region of human 22q11 are distributed on three mouse chromosomes (MMU6, MMU10, and MMU16). Furthermore, although the region corresponding to about 2.5 megabases of the VCFS/DGS critical region is located on mouse chromosome 16, the relative organization of the region is quite different from that in humans. Our results show that the instability of the 22q11 region is not restricted to humans but may have been present throughout evolution. The results also underscore the importance of detailed comparative mapping of genes in mice and humans as a prerequisite for the development of mouse models of human diseases involving chromosomal rearrangements.

Characterization and mutation analysis of goosecoid-like (GSCL), a homeodomain-containing gene that maps to the critical region for VCFS/DGS on 22q11

Velocardiofacial syndrome (VCFS) is a developmental disorder characterized by conotruncal heart defects, craniofacial anomalies, and learning disabilities. VCFS is phenotypically related to DiGeorge syndrome (DGS) and both syndromes are associated with hemizygous 22q11 deletions. Because many of the tissues and structures affected in VCFS/DGS derive from the pharyngeal arches of the developing embryo, it is believed that haploinsufficiency of a gene(s) involved in embryonic development may be responsible for its etiology. A homeodomain-containing gene, Goosecoidlike (GSCL), has been recently described, and it resides in the critical region for VCFS/DGS on 22q11. GSCL is related to the Goosecoid gene (GSC) in both sequence of the homeodomain and genomic organization. Gsc in the mouse is expressed during early and midembryogenesis and is required for craniofacial rib, and limb development. The chick homolog of GSCL, termed GSX, is expressed during early chick embryogenesis. We detected GSCL expression in human embryos and biphasic expression in mouse embryos. It is possible that the vertebrate GSCL gene is also required for embryonic development. Due to its location in the critical region on 22q11, GSCL is an excellent candidate gene for VCFS/DGS. The vertebrate GSC protein has the same DNA binding specificity as the Drosophila morphogen, bicoid. Upon examination of the putative GSCL promoter, we found three sequence elements with an exact match to the reverse complement of the bicoid DNA recognition motif, suggesting that GSC, or possibly GSCL itself, regulates the transcription of GSCL. Sequence analysis of the putative promoter and the coding region of GSCL was performed on the DNA template from 17 VCFS patients who did not have a detectable 22q11 deletion to identify mutations. We did not detect a mutation in this set of VCFS patients. A polymorphism was detected in codon 47 of exon 1.

The mouse poly(C)-binding protein exists in multiple isoforms and interacts with several RNA-binding proteins

The murine poly(C)-binding protein (mCBP) was previously shown to belong to the group of K-homology (KH) proteins by virtue of its homology to hnRNP-K. We have isolated cDNA-splice variants of mCBP which differ by two variable regions of 93 bp and/or 39 +/- 3 bp respectively. Both variable regions are located between the second and third KH-domain of mCBP. The characterization of a partial genomic clone enabled us to propose a model for the generation of the second variable region by the use of a putative alternative splice signal. The mCBP mRNA is expressed ubiquitously and the protein is found predominantly in the nucleus with the exception of the nucleoli. We have identified five proteins which interact with mCBP in the yeast two hybrid system: mouse y-box protein 1 (msy-1), y-box-binding protein, hnRNP-L, filamin and splicing factor 9G8. The interaction between mCBP and splicing factor 9G8 was confirmed in vivo. These results suggest a function of mCBP in RNA metabolism.

Murine protein which binds preferentially to oligo-C-rich single-stranded nucleic acids

Two single-stranded nucleic acid binding proteins mCBP and mCTBP were identified by means of their binding to a potential recombination hotspot in LTRs of mouse retro-transposons. Both are nuclear proteins of 35 and 55 kDa respectively. mCBP binds preferentially to oligo dC, mCTBP to oligo dCdT. mCBP was purified and its cDNA was isolated and sequenced.