RESUMO
Simpson-Golabi-Behmel syndrome (SGBS) is an X-linked condition characterized by pre- and postnatal overgrowth with visceral and skeletal anomalies. To identify the causative gene, breakpoints in two female patients with X;autosome translocations were identified. The breakpoints occur near the 5' and 3' ends of a gene, GPC3, that spans more than 500 kilobases in Xq26; in three families, different microdeletions encompassing exons cosegregate with SGBS. GPC3 encodes a putative extracellular proteoglycan, glypican 3, that is inferred to play an important role in growth control in embryonic mesodermal tissues in which it is selectively expressed. Initial western- and ligand-blotting experiments suggest that glypican 3 forms a complex with insulin-like growth factor 2 (IGF2), and might thereby modulate IGF2 action.
Assuntos
Anormalidades Múltiplas/genética , Aberrações Cromossômicas/genética , Transtornos do Crescimento/genética , Proteoglicanas de Heparan Sulfato , Heparitina Sulfato/genética , Proteoglicanas/genética , Cromossomo X , Sequência de Aminoácidos , Animais , Sequência de Bases , Linhagem Celular , Transtornos Cromossômicos , Mapeamento Cromossômico , Cromossomos Humanos Par 1 , Cromossomos Humanos Par 16 , Clonagem Molecular , Primers do DNA , Feminino , Deleção de Genes , Ligação Genética , Glipicanas , Células HeLa , Heparitina Sulfato/metabolismo , Humanos , Técnicas Imunológicas , Fator de Crescimento Insulin-Like II/metabolismo , Masculino , Camundongos , Dados de Sequência Molecular , Linhagem , Ligação Proteica , Proteoglicanas/metabolismo , Homologia de Sequência de Aminoácidos , Síndrome , Translocação Genética , Células Tumorais CultivadasRESUMO
Ectodermal dysplasias comprise over 150 syndromes of unknown pathogenesis. X-linked anhidrotic ectodermal dysplasia (EDA) is characterized by abnormal hair, teeth and sweat glands. We now describe the positional cloning of the gene mutated in EDA. Two exons, separated by a 200-kilobase intron, encode a predicted 135-residue transmembrane protein. The gene is disrupted in six patients with X;autosome translocations or submicroscopic deletions; nine patients had point mutations. The gene is expressed in keratinocytes, hair follicles, and sweat glands, and in other adult and fetal tissues. The predicted EDA protein may belong to a novel class with a role in epithelial-mesenchymal signalling.
Assuntos
Displasia Ectodérmica/genética , Hipo-Hidrose/genética , Proteínas de Membrana/genética , Anormalidades Dentárias/genética , Cromossomo X/genética , Adulto , Alelos , Alopecia/genética , Sequência de Aminoácidos , Sequência de Bases , Cromossomos Artificiais de Levedura , Ilhas de CpG , Primers do DNA/química , DNA Complementar/genética , Ectodisplasinas , Expressão Gênica , Ligação Genética , Cabelo/anormalidades , Cabelo/fisiologia , Humanos , Hibridização In Situ , Masculino , Dados de Sequência Molecular , Regiões Promotoras Genéticas , RNA Mensageiro/genética , Fenômenos Fisiológicos da Pele , Translocação GenéticaRESUMO
Ordered shotgun sequencing (OSS) has been successfully carried out with an Xq25 YAC substrate. yWXD703 DNA was subcloned into lambda phage and sequences of insert ends of the lambda subclones were used to generate a map to select a minimum tiling path of clones to be completely sequenced. The sequence of 135 038 nt contains the entire ANT2 cDNA as well as four other candidates suggested by computer-assisted analyses. One of the putative genes is homologous to a gene implicated in Graves' disease and it, ANT2 and two others are confirmed by EST matches. The results suggest that OSS can be applied to YACs in accord with earlier simulations and further indicate that the sequence of the YAC accurately reflects the sequence of uncloned human DNA.
Assuntos
Cromossomos Artificiais de Levedura/genética , Análise de Sequência/métodos , Cromossomo X/genética , Bacteriófago lambda/genética , Clonagem Molecular , Primers do DNA , Feminino , Humanos , Dados de Sequência Molecular , Reação em Cadeia da Polimerase , Sequências Repetitivas de Ácido Nucleico , Sitios de Sequências Rotuladas , SoftwareRESUMO
In order to identify the gene for human X-linked anhidrotic ectodermal dysplasia (EDA), a translocation breakpoint in a female with t(X;1)(q13.1;p36.3) and EDA (patient AK) was finely mapped. The EDA region contains five groups of rare-cutter restriction sites that define CpG islands. The two more centromeric of these islands are associated with transcripts of 3.5 kb and 1.8 kb. The third CpG island maps within <1 kb of the translocation breakpoint in patient AK, as indicated by a genomic rearrangement, and approximately 100 kb centromeric from another previously mapped translocation breakpoint (patient AnLy). Northern analysis with a probe from this CpG island detected an approximately 6-kb mRNA in several fetal tissues tested. An extended YAC contig of 1,200 kb with an average of fivefold coverage was constructed. The two most telomeric CpG islands map 350 kb telomeric of the two translocations. Taken together, the results suggest that the CpG island just proximal of the AK translocation breakpoint lies at the 5' end of a candidate gene for EDA.