Showing papers by "Uta Francke published in 2000"

A Physical Map, Including a BAC/PAC Clone Contig, of the Williams-Beuren Syndrome–Deletion Region at 7q11.23

Abstract: Summary Williams-Beuren syndrome (WBS) is a developmental disorder caused by haploinsufficiency for genes in a 2-cM region of chromosome band 7q11.23. With the exception of vascular stenoses due to deletion of the elastin gene, the various features of WBS have not yet been attributed to specific genes. Although ⩾16 genes have been identified within the WBS deletion, completion of a physical map of the region has been difficult because of the large duplicated regions flanking the deletion. We present a physical map of the WBS deletion and flanking regions, based on assembly of a bacterial artificial chromosome/P1-derived artificial chromosome contig, analysis of high-throughput genome-sequence data, and long-range restriction mapping of genomic and cloned DNA by pulsed-field gel electrophoresis. Our map encompasses 3 Mb, including 1.6 Mb within the deletion. Two large duplicons, flanking the deletion, of ⩾320 kb contain unique sequence elements from the internal border regions of the deletion, such as sequences from GTF2I (telomeric) and FKBP6 (centromeric). A third copy of this duplicon exists in inverted orientation distal to the telomeric flanking one. These duplicons show stronger sequence conservation with regard to each other than to the presumptive ancestral loci within the common deletion region. Sequence elements originating from beyond 7q11.23 are also present in these duplicons. Although the duplicons are not present in mice, the order of the single-copy genes in the conserved syntenic region of mouse chromosome 5 is inverted relative to the human map. A model is presented for a mechanism of WBS-deletion formation, based on the orientation of duplicons' components relative to each other and to the ancestral elements within the deletion region.

Small Evolutionarily Conserved RNA, Resembling C/D Box Small Nucleolar RNA, Is Transcribed from PWCR1, a Novel Imprinted Gene in the Prader-Willi Deletion Region, Which Is Highly Expressed in Brain

Abstract: Prader-Willi syndrome is a complex neurodevelopmental disorder caused by the inactivation or deletion of imprinted, paternally expressed genes in chromosome band 15q11.2. We report the identification and characterization of PWCR1, a novel imprinted gene within that region, and its mouse orthologue, Pwcr1, which was mapped to the conserved syntenic region on mouse chromosome 7. Expressed only from the paternal allele, both genes require the imprinting-center regulatory element for expression and are transcribed from the same strand. They are intronless and do not appear to encode a protein product. High human/mouse sequence similarity (87% identity) is limited to a 99-bp region called “HMCR” (for “human-mouse conserved region”). The HMCR sequence has features of a C/D box small nucleolar RNA (snoRNA) and is represented in an abundant small transcript in both species. Located in nucleoli, snoRNAs serve as methylation guidance RNAs in the modification of ribosomal RNA and other small nuclear RNAs. In addition to the nonpolyadenylated small RNAs, larger polyadenylated PWCR1 transcripts are found in most human tissues, whereas expression of any Pwcr1 RNAs is limited to mouse brain. Genomic sequence analysis reveals the presence of multiple copies of PWCR1 and Pwcr1 that are organized within local tandem-repeat clusters. On a multispecies Southern blot, hybridization to an HMCR probe encoding the putative snoRNA is limited to mammals.

Manifestations and linkage analysis in X-linked autoimmunity-immunodeficiency syndrome.

Abstract: The clinical findings of a kindred with an X-linked disorder are characterized by autoimmune polyendocrinopathy, enteropathy with villous atrophy, chronic dermatitis, and variable immunodeficiency. Linkage analysis was performed on 20 members of the affected kindred to determine the location of the responsible locus. Informative recombinations limited the region to an approximate 20 cM interval bordered by DXS1055 and DXS1196/DXS1050. Multipoint analysis generated a lod score >3 for the region contained between DXS8024 and DXS8031. The candidate region includes the Wiskott-Aldrich syndrome (WAS) locus. Evaluation of the Wiskott-Aldrich syndrome protein gene by single strand conformational analysis, heteroduplex analysis, and direct sequencing of the 12 exons in an affected male and two carrier females revealed no abnormalities. We conclude that this kindred has an X-linked disorder, distinct from WAS, that results in autoimmunity and variable immunodeficiency. The responsible locus maps to the pericentromeric region Xp11.23 to Xq21.1.

Expression of human Wiskott-Aldrich syndrome protein in patients' cells leads to partial correction of a phenotypic abnormality of cell surface glycoproteins.

Abstract: The Wiskott-Aldrich syndrome (WAS) is an uncommon X-linked recessive disease characterized by thrombocytopenia, eczema and immunodeficiency. The biochemical defect of this disorder primarily affects cells derived from bone marrow. To understand better the molecular mechanisms underlying this disease and to evaluate the possibility of correcting the genetic defects in hematopoietic cells, a Moloney murine leukemia virus (MoMLV)- based retroviral vector carrying a functional Wiskott-Aldrich syndrome protein (WASp) cDNA driven by an SV40 promoter (LNS-WASp) was constructed. A packaging cell line containing this vector produced a stable level of WAS protein and maintained a high titer of viral output. Epstein-Barr virus (EBV)-transformed B lymphoblastoid cell lines (B-LCL) from WAS patients, which lack expression of the WAS protein, were transduced by the LNS-WASp retroviral vector and showed expression of WASp by Western blot. Analysis of the O-glycan pattern on cell surface glycoproteins from WAS patients' B-LCL showed an altered glycosylation pattern, due to increased activity of beta-1, 6-N-acetylglucosaminyltransferase (C2GnT). Transduction by the retroviral vector carrying the functional WASp cDNA partially restored the abnormal glycosylation pattern, and was accompanied by a decreasing C2GnT activity. These findings imply a functional linkage between the WAS protein and the expression of the glycosyltransferase involved in the O-glycosylation, and also suggest a potential gene therapy via transferring a functional WASp cDNA into hematopoietic cells for Wiskott-Aldrich syndrome. Gene Therapy (2000) 7, 314-320.

Diverse deletions in the growth hormone receptor gene cause growth hormone insensitivity syndrome.

Abstract: Growth hormone insensitivity syndrome (GHIS; also known as Laron syndrome), is characterized by severe postnatal growth failure and normal growth hormone. The syndrome is frequently caused by point mutations in the growth hormone receptor gene (GHR). Here we report five families with GHIS and partial deletions of the GHR gene. The deletion breakpoints were sequenced and PCR-based diagnostic tests were developed. In a Cambodian family, a novel deletion removed part of exon 5 and 1.2 kb of the preceding intron. The deletion occurred by recombination within four identical nucleotides. In the mutant transcript, skipping of the truncated exon 5 leads to a frameshift and premature termination codon (PTC). A previously reported discontinuous deletion of GHR exons 3, 5, and 6 was identified in three Oriental Jewish families. An unaffected individual was heterozygous for the exon 5 and 6 deletion, but homozygously deleted for exon 3 suggesting that the exon 3 deletion is a polymorphism. The pathogenic deletion of exons 5 and 6 spans about 7.5 kb. Sequence analysis of the breakpoints revealed an imperfect junction between introns 4 and 6, with a four basepair insertion. A novel deletion of 13 nucleotides within exon 9 was identified in a Caucasian girl with GHIS who carries the I153T missense mutation on her other allele. The exon 9 deletion leads to a frameshift and PTC. The predicted protein retains the transmembrane domain and a short cytoplasmic tail. Four family members in three generations were carriers of this deletion, but only two of them were below normal for height, suggesting that this mutation by itself does not act as a dominant negative, as was reported for two other GHR mutations which lead to truncation of the intracellular domain.

My Year as 1999 ASHG President

Abstract: Upon our request, the Society has been admitted to full membership in FASEB (the Federation of American Societies of Experimental Biology), the nation's largest association of biomedical scientists. Made up of 19 societies, with a combined total of 63,000 members, FASEB has a strong voice on matters of legislative and public interest and has campaigned successfully for increased biomedical research funding. We have appointed ASHG representatives to the FASEB Board of Directors and to seven different committees dealing with research funding, public affairs, and science policy.In national debates about guidelines and regulations, many issues have come to the forefront and will continue to be addressed by the Society, its committees, and its members. These include the overhaul of the NIH peer-review system, the establishment of PubMed Central, the derivation and use of human pluripotent stem cells in research, the use of archived human tissues for research, federal oversight of genetic testing, and patenting of human genes and of genetic diagnostic tests. The protection of human subjects from research risks—including the protection of the privacy of genetic information collected as part of family studies—and issues of informed consent procedures for mentally disabled persons have caught public attention. With the formation of the Office of Human Research Protection (OHRP) under the Secretary of HHS—replacing the Office of Protection from Research Risks (OPRR) under the NIH Director—there will be increased scrutiny of informed-consent procedures and of the role of Institutional Review Boards. These developments are likely to have considerable impact on researchers in human genetics.Under John Carey, an Ad Hoc Committee on Consumer Issues has been formed of researchers and leaders of advocacy groups. With the support of ASHG, a workshop was held to address consumer issues surrounding participation in clinical genetic research. The combined voice of researchers and consumer advocates will be needed to ensure that the progress of research will not be impeded by—and will be conducted within the framework of—existing federal regulations. The ASHG Social Issues Committee, under Mark Rothstein, has developed a statement on Genetic Testing in Adoption that will soon be released. As Social Issue Committees of other genetics organizations (ACMG, NSGC, and ISONG) are dealing with similar topics, the Board strongly encouraged joint sessions and activities of the ASHG committee with these committees.To improve communication between the ASHG officers, the membership, and the public, a Communications Committee has been established by the Board to redesign our Web site, making it more visible, informative, and interactive. This effort should enable ASHG members to be informed of critical issues in a timely fashion and to act in influencing public policy. Active participation of the ASHG membership will be essential for some of these complex issues.With increasing globalization, the communication between human genetics societies around the world is facilitated by the formation of the International Federation of Human Genetics Societies (IFHGS). The Federation currently has three full members—the regional societies ASHG, ESHG (European Society of Human Genetics), and HGSA (Human Genetics Society of Australasia)—and over 30 national societies as corresponding members. As I am beginning a three-year term as President of the IFHGS, I look forward to expanding the activities of this global organization in the information age. The new IFHGS web site is http://www.faseb.org/genetics/ifhgs/index.html. Elaine Strass, the ASHG Executive Director, deserves recognition for her expert management of the Society's office in Bethesda and special gratitude for serving as IFHGS Executive Secretary as well.