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C L Shovlin

Publications and source records attributed to C L Shovlin.

15 recordsLinked to original sources
PubMed1998

Glaxo/MRS Young Investigator Medal. Molecular studies on adenosine deaminase deficiency and hereditary haemorrhagic telangiectasia.

1. This manuscript describes two different strategies to progress from the clinical assessment of patients to the identification of disease-causing mutations. In the first disease, recognition of a metabolic abnormality allowed direct molecular analysis of the causal gene. In contrast, localization of the second disease gene by linkage analysis was critical to implicate a gene with a previously unsuspected disease role. 2. Two sisters with chronic respiratory disease and recurrent infections were identified as the first cases of adult onset immunodeficiency due to adenosine deaminase deficiency. Autosomal recessive inheritance of two mutations in the adenosine deaminase gene was demonstrated. Enzyme replacement therapy improved the patients' immunological and clinical status. 3. Individuals with pulmonary arteriovenous malformations were used to identify families with hereditary haemorrhagic telangiectasia (HHT, Rendu-Osler-Weber Syndrome). Linkage studies mapped the HHT disease gene in some families to chromosome 9, and demonstrated genetic heterogeneity. The chromosome 9 disease interval was refined, and several candidate genes were assessed. Following the first description of disease-segregating mutations, a complete analysis of the endoglin gene (which encodes an endothelial cell transforming growth factor-beta receptor) identified seven novel mutations. Two mutations did not produce mutant mRNA, and disease severity was comparable between families, indicating that HHT results from stoichiometric insufficiency of endoglin. 4. Each study has implications extending beyond the relatively rare disease analysed. The adenosine-deaminase-deficient patients highlight a treatable cause of HIV-negative CD4+ lymphopenia in adults, perhaps accounting for further cases of 'non-HIV AIDS'. The HHT studies have illuminated a novel area of vascular pathophysiology, with potential relevance to further disease states.

Adenosine Deaminase↗
PubMed1997

Characterization of endoglin and identification of novel mutations in hereditary hemorrhagic telangiectasia.

To identify mutations that cause hereditary hemorrhagic telangiectasia (HHT, or Rendu-Osler-Weber syndrome), clinical evaluations and genetic studies were performed on 32 families. Linkage studies in four of eight families indicated an endoglin (ENG) gene mutation. ENG sequences of affected members of the four linked families and probands from the 24 small families were screened for mutations, by Southern blot analyses and by cycle sequencing of PCR-amplified DNA. Seven novel mutations were identified in eight families. Two mutations (a termination codon in exon 4 and a large genomic deletion extending 3' of intron 8) did not produce a stable ENG transcript in lymphocytes. Five other mutations (two donor splice-site mutations and three deletions) produce altered mRNAs that are predicted to encode markedly truncated ENG proteins. Mutations in other families are predicted to lie in ENG-regulatory regions or in one of the additional genes that may cause HHT. These data suggest that the molecular mechanism by which ENG mutations cause HHT is haploinsufficiency. Furthermore, because the clinical manifestation of disease in these eight families was similar, we hypothesize that phenotypic variation of HHT is not related to a particular ENG mutation.

Adult↗
PubMed1997

Molecular defects in rare bleeding disorders: hereditary haemorrhagic telangiectasia.

Vascular diseases may mimic coagulopathies by presenting as a haemorrhagic state. The archetypal example of an inherited disorder resulting in haemorrhage from dilated vessels of the microvasculature (telangiectasia) is Hereditary Haemorrhagic Telangiectasia (HHT, Rendu-Osler-Weber syndrome). This autosomal dominant disorder is characterised by haemorrhage from nasal, mucocutaneous and gastrointestinal telangiectasia, in addition to vascular anomalies in other organs, particularly in the pulmonary, hepatic and cerebral circulations. Linkage analyses have indicated there are at least three HHT loci, including the genes for endoglin on chromosome 9, and activin-like receptor kinase (ALK1) on chromosome 12. Mutations in these genes, together with recent data on the normal function of the encoded proteins highlight the role of TGF-b family members in the pathogenesis of HHT. Complimentary information from other telangiectatic states indicates potential precipitants, and indicate a critical role for TGF-beta ligand-receptor interactions in vascular homeostasis.

Activin Receptors↗
PubMed1996

Genetic analysis of susceptibility to experimental autoimmune encephalomyelitis in a cross between SJL/J and B10.S mice.

Experimental autoimmune encephalomyelitis (EAE), a model for human multiple sclerosis, is a T cell-mediated autoimmune disease that can be induced in experimental animals by immunization with myelin Ags. Inbred strains of mice show varying degrees of susceptibility to EAE, indicating that susceptibility is an inherited trait. To define the genetic factors that control susceptibility to EAE, we performed linkage analysis on the first backcross (BC1) between highly susceptible SJL/J mice and resistant B10.S mice, both of which are of the H-2s haplotype. Mice were immunized for disease with encephalitogenic myelin proteolipid protein peptide 139 to 151, and analysis was performed on 68 backcross mice showing the severe disease phenotype (disease score > or = 3)and 68 backcross mice of the resistant phenotype (no clinical or histologic signs of disease) using microsatellite markers covering >98% of the genome. We found the strongest linkage (p = 0.001) with clinical disease at two loci: one at the telomeric end of chromosome 2, and another near the center of chromosome 3. In addition, several other regions showing some evidence of linkage (p < or = 0.05) with clinical disease were found.

Animals↗
PubMed1996

Inherited diseases of the vasculature.

This review focuses on a spectrum of inherited disorders in which recent genetic advances have made a significant contribution to our understanding of vascular pathology and homeostasis. They are discussed according to the type of blood vessel affected and the compounded physiological processes that include angiogenesis, vascular development, and defects in the structure and regulation of the mature vessel. Vascular malformations, arterial aneurysms and dissection, telangiectasia, infiltrative vascular disease, and inherited tumors and disorders of neovascularization are discussed in a variety of settings. Disease roles for endoglin, tissue inhibitor of metalloproteinases 3 (TIMP3), and vascular endothelial growth factor (VEGF) dysregulation are highlighted (175 references).

Animals↗
PubMed1995

Medical complications of pregnancy in hereditary haemorrhagic telangiectasia.

Hereditary haemorrhagic telangiectasia (HHT) displays significant variation in severity between affected individuals in the same family, ranging from relatively trivial epistaxis and telangiectasia to gastrointestinal, cerebral and pulmonary involvement. Evidence for successful therapy of HHT-related haemorrhage with oestrogens and progesterones, and recent case reports outlining pulmonary complications of pregnancy in HHT, prompted us to review the outcome of 161 pregnancies in 47 affected women. HHT-related maternal complications developed in eleven patients, ten in the subgroup of 23 pregnancies in which pulmonary arteriovenous malformations (PAVMs) were present at the outset, or documented in the two years following pregnancy. We present six cases of intrapulmonary shunt deterioration, two cases of fatal pulmonary haemorrhage and three cerebrovascular accidents related to pregnancy. A predisposition towards PAVMs in females was observed. Following the recent discovery of mutations in the endoglin gene in this disease, our data support a hypothesis of hormonal modification of the HHT phenotype. In addition, a significant excess of affected offspring are present in HHT families. We consider contributary aetiological factors, and discuss implications for patient management.

Abortion, Spontaneous↗
PubMed1994

Adult onset immunodeficiency caused by inherited adenosine deaminase deficiency.

Adenosine deaminase (ADA) deficiency is identified here as a cause of adult onset immunodeficiency. Two sisters who noted recurrent, predominantly chest infections in their twenties were found in their thirties to have CD4+ lymphopenia and lymphocyte ADA activity of approximately 5% of the lower limit of normal. Immune function, measured by proliferation of PBMCs in vitro to mitogens and specific Ags, was impaired. Inheritance of a polymorphic marker showed that both patients were heterozygous at the ADA locus. In the paternal allele there was a deletion resulting from homologous recombination between two alu elements that normally flank the first exon and the polymorphic marker. The recombination site was distinct from that in similar deletions described in two infants having severe combined immunodeficiency. This allele is predicted to result in a null phenotype. In the mutant allele inherited from the mother, a C to T transition in a CpG dinucleotide changed the codon for arginine 211, which lies in a conserved sequence close to the active site, to that for cysteine. This mutation has been observed previously in a child in whom the other allele was also a null mutation, but who was diagnosed as having partial ADA deficiency because immune function was apparently normal. The late onset of immunodeficiency in our patients suggests that immune function in children with partial ADA deficiency may deteriorate with time and that ADA deficiency should be regarded as a possible cause of adult onset immune dysfunction of unknown etiology.

Adenosine Deaminase↗
PubMed1994

A gene for hereditary haemorrhagic telangiectasia maps to chromosome 9q3.

Hereditary haemorrhagic telangiectasia (HHT) is an autosomal dominant vascular disorder that is characterized by frequent nosebleeds, mucocutaneous telangiectases and vascular malformations that cause recurrent haemorrhage and arteriovenous shunting. Linkage analyses in one kindred identified an HHT locus on the long arm of chromosome 9 (maximum multipoint lod score = 6.20 between D9S60 and D9S61). Analyses in two other unrelated HHT families demonstrated that the disease in one was not linked to the locus on chromosome 9q3. We conclude that HHT is a genetically heterogeneous disorder. Based on its map location (9q3) and expression in vascular tissues, type V collagen is a possible candidate gene for HHT.

Adult↗