Publications by authors named "Heather Fawcett"

10 Publications

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Functional and clinical relevance of novel mutations in a large cohort of patients with Cockayne syndrome.

J Med Genet 2018 05 23;55(5):329-343. Epub 2018 Mar 23.

Genome Damage and Stability Centre, University of Sussex, Brighton, UK.

Background: Cockayne syndrome (CS) is a rare, autosomal recessive multisystem disorder characterised by prenatal or postnatal growth failure, progressive neurological dysfunction, ocular and skeletal abnormalities and premature ageing. About half of the patients with symptoms diagnostic for CS show cutaneous photosensitivity and an abnormal cellular response to UV light due to mutations in either the / or / gene. Studies performed thus far have failed to delineate clear genotype-phenotype relationships. We have carried out a four-centre clinical, molecular and cellular analysis of 124 patients with CS.

Methods And Results: We assigned 39 patients to the and 85 to the genes. Most of the genetic variants were truncations. The missense variants were distributed non-randomly with concentrations in relatively short regions of the respective proteins. Our analyses revealed several hotspots and founder mutations in Although no unequivocal genotype-phenotype relationships could be made, patients were more likely to have severe clinical features if the mutation was downstream of the PiggyBac insertion in intron 5 of than if it was upstream. Also a higher proportion of severely affected patients was found with mutations in than in .

Conclusion: By identifying >70 novel homozygous or compound heterozygous genetic variants in 124 patients with CS with different disease severity and ethnic backgrounds, we considerably broaden the and mutation spectrum responsible for CS. Besides providing information relevant for diagnosis of and genetic counselling for this devastating disorder, this study improves the definition of the puzzling genotype-phenotype relationships in patients with CS.
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http://dx.doi.org/10.1136/jmedgenet-2017-104877DOI Listing
May 2018

Deep phenotyping of 89 xeroderma pigmentosum patients reveals unexpected heterogeneity dependent on the precise molecular defect.

Proc Natl Acad Sci U S A 2016 Mar 16;113(9):E1236-45. Epub 2016 Feb 16.

Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton BN1 9RQ, United Kingdom;

Xeroderma pigmentosum (XP) is a rare DNA repair disorder characterized by increased susceptibility to UV radiation (UVR)-induced skin pigmentation, skin cancers, ocular surface disease, and, in some patients, sunburn and neurological degeneration. Genetically, it is assigned to eight complementation groups (XP-A to -G and variant). For the last 5 y, the UK national multidisciplinary XP service has provided follow-up for 89 XP patients, representing most of the XP patients in the United Kingdom. Causative mutations, DNA repair levels, and more than 60 clinical variables relating to dermatology, ophthalmology, and neurology have been measured, using scoring systems to categorize disease severity. This deep phenotyping has revealed unanticipated heterogeneity of clinical features, between and within complementation groups. Skin cancer is most common in XP-C, XP-E, and XP-V patients, previously considered to be the milder groups based on cellular analyses. These patients have normal sunburn reactions and are therefore diagnosed later and are less likely to adhere to UVR protection. XP-C patients are specifically hypersensitive to ocular damage, and XP-F and XP-G patients appear to be much less susceptible to skin cancer than other XP groups. Within XP groups, different mutations confer susceptibility or resistance to neurological damage. Our findings on this large cohort of XP patients under long-term follow-up reveal that XP is more heterogeneous than has previously been appreciated. Our data now enable provision of personalized prognostic information and management advice for each XP patient, as well as providing new insights into the functions of the XP proteins.
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http://dx.doi.org/10.1073/pnas.1519444113DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4780618PMC
March 2016

A Distinct Genotype of XP Complementation Group A: Surprisingly Mild Phenotype Highly Prevalent in Northern India/Pakistan/Afghanistan.

J Invest Dermatol 2016 Apr 29;136(4):869-872. Epub 2015 Dec 29.

National Xeroderma Pigmentosum Service, Department of Photodermatology, St. John's Institute of Dermatology, Guy's and St. Thomas' NHS Foundation Trust, London, United Kingdom. Electronic address:

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http://dx.doi.org/10.1016/j.jid.2015.12.031DOI Listing
April 2016

XRCC4 deficiency in human subjects causes a marked neurological phenotype but no overt immunodeficiency.

J Allergy Clin Immunol 2015 Oct 5;136(4):1007-17. Epub 2015 Aug 5.

Department of Genetics, Research Institute of Environmental Medicine (RIeM), Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Japan; Nagasaki University Research Centre for Genomic Instability and Carcinogenesis (NRGIC), Nagasaki, Japan; Department of Molecular Medicine, Atomic Bomb Disease Institute, Nagasaki University, Nagasaki, Japan; Microbial Genetics Laboratory, Genetic Strains Research Center, National Institute of Genetics, Mishima, Japan. Electronic address:

Background: Nonhomologous end-joining (NHEJ) is the major DNA double-strand break (DSB) repair mechanism in human cells. The final rejoining step requires DNA ligase IV (LIG4) together with the partner proteins X-ray repair cross-complementing protein 4 (XRCC4) and XRCC4-like factor. Patients with mutations in genes encoding LIG4, XRCC4-like factor, or the other NHEJ proteins DNA-dependent protein kinase catalytic subunit and Artemis are DSB repair defective and immunodeficient because of the requirement for NHEJ during V(D)J recombination.

Objective: We found a patient displaying microcephaly and progressive ataxia but a normal immune response. We sought to determine pathogenic mutations and to describe the molecular pathogenesis of the patient.

Methods: We performed next-generation exome sequencing. We evaluated the DSB repair activities and V(D)J recombination capacity of the patient's cells, as well as performing a standard blood immunologic characterization.

Results: We identified causal mutations in the XRCC4 gene. The patient's cells are radiosensitive and display the most severe DSB repair defect we have encountered using patient-derived cell lines. In marked contrast, a V(D)J recombination plasmid assay revealed that the patient's cells did not display the junction abnormalities that are characteristic of other NHEJ-defective cell lines. The mutant protein can interact efficiently with LIG4 and functions normally in in vitro assays and when transiently expressed in vivo. However, the mutation makes the protein unstable, and it undergoes proteasome-mediated degradation.

Conclusion: Our findings reveal a novel separation of impact phenotype: there is a pronounced DSB repair defect and marked clinical neurological manifestation but no clinical immunodeficiency.
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http://dx.doi.org/10.1016/j.jaci.2015.06.007DOI Listing
October 2015

Hypomorphic PCNA mutation underlies a human DNA repair disorder.

J Clin Invest 2014 Jul 9;124(7):3137-46. Epub 2014 Jun 9.

Numerous human disorders, including Cockayne syndrome, UV-sensitive syndrome, xeroderma pigmentosum, and trichothiodystrophy, result from the mutation of genes encoding molecules important for nucleotide excision repair. Here, we describe a syndrome in which the cardinal clinical features include short stature, hearing loss, premature aging, telangiectasia, neurodegeneration, and photosensitivity, resulting from a homozygous missense (p.Ser228Ile) sequence alteration of the proliferating cell nuclear antigen (PCNA). PCNA is a highly conserved sliding clamp protein essential for DNA replication and repair. Due to this fundamental role, mutations in PCNA that profoundly impair protein function would be incompatible with life. Interestingly, while the p.Ser228Ile alteration appeared to have no effect on protein levels or DNA replication, patient cells exhibited marked abnormalities in response to UV irradiation, displaying substantial reductions in both UV survival and RNA synthesis recovery. The p.Ser228Ile change also profoundly altered PCNA's interaction with Flap endonuclease 1 and DNA Ligase 1, DNA metabolism enzymes. Together, our findings detail a mutation of PCNA in humans associated with a neurodegenerative phenotype, displaying clinical and molecular features common to other DNA repair disorders, which we showed to be attributable to a hypomorphic amino acid alteration.
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http://dx.doi.org/10.1172/JCI74593DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4071375PMC
July 2014

Malfunction of nuclease ERCC1-XPF results in diverse clinical manifestations and causes Cockayne syndrome, xeroderma pigmentosum, and Fanconi anemia.

Am J Hum Genet 2013 May 25;92(5):807-19. Epub 2013 Apr 25.

Department of Plastic and Reconstructive Surgery, Graduate School of Biomedical Sciences, Nagasaki University, 1-7-1 Sakamoto, Nagasaki 852-8501, Japan.

Cockayne syndrome (CS) is a genetic disorder characterized by developmental abnormalities and photodermatosis resulting from the lack of transcription-coupled nucleotide excision repair, which is responsible for the removal of photodamage from actively transcribed genes. To date, all identified causative mutations for CS have been in the two known CS-associated genes, ERCC8 (CSA) and ERCC6 (CSB). For the rare combined xeroderma pigmentosum (XP) and CS phenotype, all identified mutations are in three of the XP-associated genes, ERCC3 (XPB), ERCC2 (XPD), and ERCC5 (XPG). In a previous report, we identified several CS cases who did not have mutations in any of these genes. In this paper, we describe three CS individuals deficient in ERCC1 or ERCC4 (XPF). Remarkably, one of these individuals with XP complementation group F (XP-F) had clinical features of three different DNA-repair disorders--CS, XP, and Fanconi anemia (FA). Our results, together with those from Bogliolo et al., who describe XPF alterations resulting in FA alone, indicate a multifunctional role for XPF.
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http://dx.doi.org/10.1016/j.ajhg.2013.04.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3644632PMC
May 2013

A rapid non-radioactive technique for measurement of repair synthesis in primary human fibroblasts by incorporation of ethynyl deoxyuridine (EdU).

Nucleic Acids Res 2009 Mar 29;37(4):e31. Epub 2009 Jan 29.

Department of Molecular Medicine, Atomic Bomb Disease Institute, Nagasaki University, Nagasaki, 852-8523 Japan.

Xeroderma pigmentosum (XP) is an autosomal recessive genetic disorder. Afflicted patients show extreme sun-sensitivity and skin cancer predisposition. XP is in most cases associated with deficient nucleotide excision repair (NER), which is the process responsible for removing photolesions from DNA. Measuring NER activity by nucleotide incorporation into repair patches, termed 'unscheduled DNA synthesis (UDS)', is one of the most commonly used assays for XP-diagnosis and NER research. We have established a rapid and accurate procedure for measuring UDS by replacement of thymidine with 5-ethynyl-2'-deoxyuridine (EdU). EdU incorporated into repair patches can be directly conjugated to fluorescent azide derivatives, thereby obviating the need for either radiolabeled thymidine or denaturation and antibody detection of incorporated bromodeoxyuridine (BrdU). We demonstrate that the EdU incorporation assay is compatible with conventional techniques such as immunofluorescent staining and labeling of cells with micro-latex beads. Importantly, we can complete the entire UDS assay within half a day from preparation of the assay coverslips; this technique may prove useful as a method for XP diagnosis.
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http://dx.doi.org/10.1093/nar/gkp023DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2651789PMC
March 2009

Incidence of DNA repair deficiency disorders in western Europe: Xeroderma pigmentosum, Cockayne syndrome and trichothiodystrophy.

DNA Repair (Amst) 2008 May 10;7(5):744-50. Epub 2008 Mar 10.

Department of Clinical Genetics, Erasmus Medical Centre, Rotterdam, The Netherlands.

Laboratory diagnosis for DNA repair diseases has been performed in western Europe from the early seventies for xeroderma pigmentosum (XP) and from the mid-eighties for Cockayne syndrome (CS) and trichothiodystrophy (TTD). The combined data from the DNA repair diagnostic centres in France, (West) Germany, Italy, the Netherlands and the United Kingdom have been investigated for three groups of diseases: XP (including XP-variant), CS (including XP/CS complex) and TTD. Incidences in western Europe were for the first time established at 2.3 per million livebirths for XP, 2.7 per million for CS and 1.2 per million for TTD. As immigrant populations were disproportionately represented in the patients' groups, incidences were also established for the autochthonic western European population at: 0.9 per million for XP, 1.8 per million for CS and 1.1 per million for TTD. Perhaps contrary to general conceptions, compared to XP the incidence of CS appears to be somewhat higher and the incidence of TTD to be quite similar in the native West-European population.
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http://dx.doi.org/10.1016/j.dnarep.2008.01.014DOI Listing
May 2008

Two new XPD patients compound heterozygous for the same mutation demonstrate diverse clinical features.

J Invest Dermatol 2005 Jul;125(1):86-92

Department of Dermatology, Jichi Medical School, Japan.

Xeroderma pigmentosum (XP) and Cockayne syndrome (CS) are both rare autosomal recessive disorders with defects in DNA repair. They are usually distinct both clinically and genetically but in rare cases, patients exhibit the clinical characteristics of both diseases concurrently. We report two new phenotypically distinct cases of XP with additional features of CS (xeroderma pigmentosum and Cockayne syndrome crossover syndrome (XP/CS)) carrying an identical mutation (G47R) in the XPD gene within the N terminus of the protein. Both patients had clinical features of XP and CS but only one fulfilled most criteria for diagnosing CS. Unusually, patient 1 developed early skin cancer, in contrast to patient 2, who never developed any malignancies. Cells from both these patients have repair defects typical of xeroderma pigmentosum complementation group D (XPD) cells, but also had the phenotype of uncontrolled DNA breakage found specifically in XPD/CS cells and similarly reduced levels of TFIIH. Despite these similarities between our two patients, their clinical features are quite different and the clinical severity correlates with other cellular responses to ultraviolet irradiation.
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http://dx.doi.org/10.1111/j.0022-202X.2005.23745.xDOI Listing
July 2005

Molecular analysis of mutations in DNA polymerase eta in xeroderma pigmentosum-variant patients.

Proc Natl Acad Sci U S A 2002 Jan 2;99(2):815-20. Epub 2002 Jan 2.

Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton BN1 9RR, United Kingdom.

Xeroderma pigmentosum variant (XP-V) cells are deficient in their ability to synthesize intact daughter DNA strands after UV irradiation. This deficiency results from mutations in the gene encoding DNA polymerase eta, which is required for effecting translesion synthesis (TLS) past UV photoproducts. We have developed a simple cellular procedure to identify XP-V cell strains, and have subsequently analyzed the mutations in 21 patients with XP-V. The 16 mutations that we have identified fall into three categories. Many of them result in severe truncations of the protein and are effectively null alleles. However, we have also identified five missense mutations located in the conserved catalytic domain of the protein. Extracts of cells falling into these two categories are defective in the ability to carry out TLS past sites of DNA damage. Three mutations cause truncations at the C terminus such that the catalytic domains are intact, and extracts from these cells are able to carry out TLS. From our previous work, however, we anticipate that protein in these cells will not be localized in the nucleus nor will it be relocalized into replication foci during DNA replication. The spectrum of both missense and truncating mutations is markedly skewed toward the N-terminal half of the protein. Two of the missense mutations are predicted to affect the interaction with DNA, the others are likely to disrupt the three-dimensional structure of the protein. There is a wide variability in clinical features among patients, which is not obviously related to the site or type of mutation.
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http://dx.doi.org/10.1073/pnas.022473899DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC117388PMC
January 2002