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Leidenz FAB, Bittencourt FV, Braga WG, de Sá Araújo EM, Gomes CC, de Fatima Bernardes V, Friedman E, De Marco L. Familial Melanoma Phenotype With Xeroderma Pigmentosum Group C (XP-C) Genotype - The Putative Role of MC1R Polymorphism as Modifier. Dermatol Pract Concept 2024; 14:dpc.1401a50. [PMID: 38364385 PMCID: PMC10868875 DOI: 10.5826/dpc.1401a50] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/27/2023] [Indexed: 02/18/2024] Open
Abstract
INTRODUCTION Xeroderma pigmentosum (XP), a rare inherited condition, hallmarked by extreme sensitivity to sun exposure resulting in multiple skin cancers and non-malignant skin alterations is attributed to homozygous inactivating pathogenic variants (PVs) in DNA repair genes, predominantly the XPC gene. OBJECTIVES Report a unique phenotypic expression of mutant XPC allele that may be compatible with a putative modifier role for MC1R polymorphism. METHODS A family of 13 siblings, seven of whom were diagnosed with at least one cutaneous melanoma (N = 53) and non-melanoma skin cancers (N = 9) was studied. Of seven melanoma-affected cases, five consented for genetic analysis. CDKN2A revealed no PV in any case and subsequent whole-exome sequencing (WES) identified a rare homozygous missense PV (c.919C>T; p.Arg307Trp) in exon 8 of the XPC gene in all affected individuals. Notably, XPC PV carriers who co-harbored the p.I155T MC1R variant (N = 3) exhibited larger number of tumors, deeper Breslow indexes, higher rates of invasive melanomas and earlier age at diagnosis compared with non MC1R variant carriers (N = 2). CONCLUSIONS Familial malignant melanoma phenotype may, in fact, be an unusual clinical presentation of XPC, and MC1R may be a genetic modifier of penetrance and phenotype of mutant XPC alleles.
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Affiliation(s)
| | - Flavia Vasques Bittencourt
- Departments of Medicine, School of Medicine, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Williana Garcia Braga
- Departments of Surgery, School of Medicine, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Elio Magno de Sá Araújo
- Departments of Surgery, School of Medicine, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Carolina Cavalieri Gomes
- Departments of Pathology, School of Medicine, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | | | - Eitan Friedman
- The Preventive Personalized Medicine Center, Assuta Medical Center and the Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel
| | - Luiz De Marco
- Departments of Surgery, School of Medicine, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
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Zong D, Li J, Liu X, Guo T, Ouyang R. Identification of a Novel Pathogenic Folliculin Variant in a Chinese Family With Birt-Hogg-Dubé Syndrome (Hornstein-Knickenberg Syndrome). Front Genet 2020; 11:565566. [PMID: 33240319 PMCID: PMC7667195 DOI: 10.3389/fgene.2020.565566] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 10/02/2020] [Indexed: 12/15/2022] Open
Abstract
Birt–Hogg–Dubé syndrome (BHDS), which is also called Hornstein-Knickenberg syndrome (HKS), is a hereditary autosomal dominant disorder caused by germline mutations in the folliculin gene (FLCN, NM_144997). More pulmonary manifestations (pulmonary cysts and recurrent pneumothoraxes) but fewer skin fibrofolliculomas and renal malignancy are found in Asian BHDS patients compared with other BHDS patients. The atypical manifestation can easily lead to a missed or delayed diagnosis. Here, we report a Chinese family with BHDS that presented with primary spontaneous pneumothorax (PSP) and extensive pulmonary cysts in the absence of skin lesions or renal neoplasms. Next-generation sequencing (NGS) was used to sequence the FLCN gene, and Sanger sequencing was carried out on the samples to confirm the presence of these variants. Among the 13 family members, a novel frameshift variant of FLCN (c.912delT/p.E305KfsX18) was identified in seven individuals. This variant has not been reported before. Bioinformatics analysis showed that the novel variant might lead to a premature stop codon after 18 amino acid residues in exon 9, and this may affect the expression level of FLCN. The identification of this novel frameshift variant of FLCN not only further confirms the familial inheritance of BHDS in the proband but also expands the mutational spectrum of the FLCN gene in patients with BHDS.
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Affiliation(s)
- Dandan Zong
- Department of Pulmonary and Critical Care Medicine, The Second Xiangya Hospital, Central South University, Changsha, China.,Research Unit of Respiratory Disease, Central South University, Changsha, China.,Diagnosis and Treatment Center of Respiratory Disease, Central South University, Changsha, China
| | - Jinhua Li
- Department of Pulmonary and Critical Care Medicine, The Second Xiangya Hospital, Central South University, Changsha, China.,Research Unit of Respiratory Disease, Central South University, Changsha, China.,Diagnosis and Treatment Center of Respiratory Disease, Central South University, Changsha, China
| | - Xiangming Liu
- Department of Pulmonary and Critical Care Medicine, The Second Xiangya Hospital, Central South University, Changsha, China.,Research Unit of Respiratory Disease, Central South University, Changsha, China.,Diagnosis and Treatment Center of Respiratory Disease, Central South University, Changsha, China
| | - Ting Guo
- Department of Pulmonary and Critical Care Medicine, The Second Xiangya Hospital, Central South University, Changsha, China.,Research Unit of Respiratory Disease, Central South University, Changsha, China.,Diagnosis and Treatment Center of Respiratory Disease, Central South University, Changsha, China
| | - Ruoyun Ouyang
- Department of Pulmonary and Critical Care Medicine, The Second Xiangya Hospital, Central South University, Changsha, China.,Research Unit of Respiratory Disease, Central South University, Changsha, China.,Diagnosis and Treatment Center of Respiratory Disease, Central South University, Changsha, China
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Ali MZ, Blatterer J, Khan MA, Schaflinger E, Petek E, Ahmad S, Khan E, Windpassinger C. Identification of a novel protein truncating mutation p.Asp98* in XPC associated with xeroderma pigmentosum in a consanguineous Pakistani family. Mol Genet Genomic Med 2020; 8:e1060. [PMID: 31923348 PMCID: PMC7005610 DOI: 10.1002/mgg3.1060] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 10/12/2019] [Accepted: 10/23/2019] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Xeroderma pigmentosum (XP) is a rare genetic disorder, which is characterized by hyper-sensitivity to solar ultraviolet (UV) radiation. Clinical consequences of sun exposure are skin lesions and an increased risk of developing skin cancer. Genetic studies have identified eight genes associated with xeroderma pigmentosum. The proteins encoded by these genes are mainly involved in DNA repair mechanisms. METHODS Molecular genetic characterization of patients with xeroderma pigmentosum involved positional cloning methods such as homozygosity mapping and subsequent candidate gene analysis. Mutation screening was performed through Sanger DNA sequencing. RESULTS AND DISCUSSION In this case study, we report a novel protein truncating mutation in XPC associated with autosomal recessive xeroderma pigmentosum in a consanguineous Pakistani family. Genetic mapping revealed a novel single base insertion of a thymine nucleotide NM_004628.4: c.291dupT (c.291_292insT) in the second exon of XPC. The identified mutation leads to a premature stop codon (TGA) at amino acid position 98 (p.Asp98*) and thus presumably results in a truncated protein. The Xeroderma pigmentosum, complementation group C (XPC) is located on 3p25.1 and encodes a protein involved in nucleotide excision repair. The identified mutation presumably truncates all functional domains of the XPC protein, which likely results in the loss of protein function. CONCLUSION The study expands the knowledge of the mutational spectrum of XPC and is valuable for genetic counseling of affected individuals and their families.
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Affiliation(s)
- Muhammad Z Ali
- Gomal Centre of Biochemistry and Biotechnology, Gomal University, Dera Ismail Khan, Khyber Pakhtunkhwa, Pakistan
| | - Jasmin Blatterer
- Diagnostic & Research Institute of Human Genetics, Medical University of Graz, Graz, Austria
| | - Muzammil A Khan
- Gomal Centre of Biochemistry and Biotechnology, Gomal University, Dera Ismail Khan, Khyber Pakhtunkhwa, Pakistan
| | - Erich Schaflinger
- Diagnostic & Research Institute of Human Genetics, Medical University of Graz, Graz, Austria
| | - Erwin Petek
- Diagnostic & Research Institute of Human Genetics, Medical University of Graz, Graz, Austria
| | - Safeer Ahmad
- Gomal Centre of Biochemistry and Biotechnology, Gomal University, Dera Ismail Khan, Khyber Pakhtunkhwa, Pakistan
| | - Ejazullah Khan
- Gomal Centre of Biochemistry and Biotechnology, Gomal University, Dera Ismail Khan, Khyber Pakhtunkhwa, Pakistan
| | - Christian Windpassinger
- Diagnostic & Research Institute of Human Genetics, Medical University of Graz, Graz, Austria
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