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Fioretti T, Martora F, De Maggio I, Ambrosio A, Piscopo C, Vallone S, Amato F, Passaro D, Acquaviva F, Gaudiello F, Di Girolamo D, Maiolo V, Zarrilli F, Esposito S, Vitiello G, Auricchio L, Sammarco E, Brasi DD, Petillo R, Gambale A, Cattaneo F, Ammendola R, Nappa P, Esposito G. Comprehensive Molecular Analysis of Disease-Related Genes as First-Tier Test for Early Diagnosis, Classification, and Management of Patients Affected by Nonsyndromic Ichthyosis. Biomedicines 2024; 12:1112. [PMID: 38791074 PMCID: PMC11117922 DOI: 10.3390/biomedicines12051112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Revised: 05/07/2024] [Accepted: 05/13/2024] [Indexed: 05/26/2024] Open
Abstract
Inherited ichthyoses are a group of clinically and genetically heterogeneous rare disorders of skin keratinization with overlapping phenotypes. The clinical picture and family history are crucial to formulating the diagnostic hypothesis, but only the identification of the genetic defect allows the correct classification. In the attempt to molecularly classify 17 unrelated Italian patients referred with congenital nonsyndromic ichthyosis, we performed massively parallel sequencing of over 50 ichthyosis-related genes. Genetic data of 300 Italian unaffected subjects were also analyzed to evaluate frequencies of putative disease-causing alleles in our population. For all patients, we identified the molecular cause of the disease. Eight patients were affected by autosomal recessive congenital ichthyosis associated with ALOX12B, NIPAL4, and TGM1 mutations. Three patients had biallelic loss-of-function variants in FLG, whereas 6/11 males were affected by X-linked ichthyosis. Among the 24 different disease-causing alleles we identified, 8 carried novel variants, including a synonymous TGM1 variant that resulted in a splicing defect. Moreover, we generated a priority list of the ichthyosis-related genes that showed a significant number of rare and novel variants in our population. In conclusion, our comprehensive molecular analysis resulted in an effective first-tier test for the early classification of ichthyosis patients. It also expands the genetic, mutational, and phenotypic spectra of inherited ichthyosis and provides new insight into the current understanding of etiologies and epidemiology of this group of rare disorders.
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Affiliation(s)
- Tiziana Fioretti
- CEINGE Advanced Biotechnologies Franco Salvatore, 80145 Naples, Italy; (T.F.); (A.A.); (S.V.); (F.A.); (F.Z.); (S.E.)
| | - Fabrizio Martora
- Section of Dermatology, Department of Clinical Medicine and Surgery, School of Medicine, University of Naples “Federico II”, 80131 Naples, Italy; (F.M.); (F.G.); (L.A.); (P.N.)
| | - Ilaria De Maggio
- Medical and Laboratory Genetics Unit, AORN A. Cardarelli, 80131 Naples, Italy; (I.D.M.); (C.P.); (R.P.)
| | - Adelaide Ambrosio
- CEINGE Advanced Biotechnologies Franco Salvatore, 80145 Naples, Italy; (T.F.); (A.A.); (S.V.); (F.A.); (F.Z.); (S.E.)
| | - Carmelo Piscopo
- Medical and Laboratory Genetics Unit, AORN A. Cardarelli, 80131 Naples, Italy; (I.D.M.); (C.P.); (R.P.)
| | - Sabrina Vallone
- CEINGE Advanced Biotechnologies Franco Salvatore, 80145 Naples, Italy; (T.F.); (A.A.); (S.V.); (F.A.); (F.Z.); (S.E.)
- Department of Molecular Medicine and Medical Biotechnologies, School of Medicine, University of Naples “Federico II”, 80131 Naples, Italy; (D.P.); (V.M.); (F.C.); (R.A.)
| | - Felice Amato
- CEINGE Advanced Biotechnologies Franco Salvatore, 80145 Naples, Italy; (T.F.); (A.A.); (S.V.); (F.A.); (F.Z.); (S.E.)
- Department of Molecular Medicine and Medical Biotechnologies, School of Medicine, University of Naples “Federico II”, 80131 Naples, Italy; (D.P.); (V.M.); (F.C.); (R.A.)
| | - Diego Passaro
- Department of Molecular Medicine and Medical Biotechnologies, School of Medicine, University of Naples “Federico II”, 80131 Naples, Italy; (D.P.); (V.M.); (F.C.); (R.A.)
| | - Fabio Acquaviva
- Medical Genetics Unit, Department of General and Emergency Paediatrics, AORN Santobono-Pausilipon, 80122 Naples, Italy; (F.A.); (D.D.B.)
| | - Francesca Gaudiello
- Section of Dermatology, Department of Clinical Medicine and Surgery, School of Medicine, University of Naples “Federico II”, 80131 Naples, Italy; (F.M.); (F.G.); (L.A.); (P.N.)
| | - Daniela Di Girolamo
- Department of Biology, University of Naples “Federico II”, 80126 Naples, Italy;
| | - Valeria Maiolo
- Department of Molecular Medicine and Medical Biotechnologies, School of Medicine, University of Naples “Federico II”, 80131 Naples, Italy; (D.P.); (V.M.); (F.C.); (R.A.)
| | - Federica Zarrilli
- CEINGE Advanced Biotechnologies Franco Salvatore, 80145 Naples, Italy; (T.F.); (A.A.); (S.V.); (F.A.); (F.Z.); (S.E.)
- Department of Molecular Medicine and Medical Biotechnologies, School of Medicine, University of Naples “Federico II”, 80131 Naples, Italy; (D.P.); (V.M.); (F.C.); (R.A.)
| | - Speranza Esposito
- CEINGE Advanced Biotechnologies Franco Salvatore, 80145 Naples, Italy; (T.F.); (A.A.); (S.V.); (F.A.); (F.Z.); (S.E.)
- Department of Molecular Medicine and Medical Biotechnologies, School of Medicine, University of Naples “Federico II”, 80131 Naples, Italy; (D.P.); (V.M.); (F.C.); (R.A.)
| | - Giuseppina Vitiello
- Medical Genetics Unit, Integrated Care Department of Laboratory and Transfusion Medicine, Federico II Hospital, 80131 Naples, Italy; (G.V.); (A.G.)
| | - Luigi Auricchio
- Section of Dermatology, Department of Clinical Medicine and Surgery, School of Medicine, University of Naples “Federico II”, 80131 Naples, Italy; (F.M.); (F.G.); (L.A.); (P.N.)
| | - Elena Sammarco
- Pediatric Dermatology Unit, Department of Dermo-Immuno-Rheumatology Paediatrics, AORN Santobono-Pausilipon, 80122 Naples, Italy;
| | - Daniele De Brasi
- Medical Genetics Unit, Department of General and Emergency Paediatrics, AORN Santobono-Pausilipon, 80122 Naples, Italy; (F.A.); (D.D.B.)
| | - Roberta Petillo
- Medical and Laboratory Genetics Unit, AORN A. Cardarelli, 80131 Naples, Italy; (I.D.M.); (C.P.); (R.P.)
| | - Antonella Gambale
- Medical Genetics Unit, Integrated Care Department of Laboratory and Transfusion Medicine, Federico II Hospital, 80131 Naples, Italy; (G.V.); (A.G.)
| | - Fabio Cattaneo
- Department of Molecular Medicine and Medical Biotechnologies, School of Medicine, University of Naples “Federico II”, 80131 Naples, Italy; (D.P.); (V.M.); (F.C.); (R.A.)
| | - Rosario Ammendola
- Department of Molecular Medicine and Medical Biotechnologies, School of Medicine, University of Naples “Federico II”, 80131 Naples, Italy; (D.P.); (V.M.); (F.C.); (R.A.)
| | - Paola Nappa
- Section of Dermatology, Department of Clinical Medicine and Surgery, School of Medicine, University of Naples “Federico II”, 80131 Naples, Italy; (F.M.); (F.G.); (L.A.); (P.N.)
| | - Gabriella Esposito
- CEINGE Advanced Biotechnologies Franco Salvatore, 80145 Naples, Italy; (T.F.); (A.A.); (S.V.); (F.A.); (F.Z.); (S.E.)
- Department of Molecular Medicine and Medical Biotechnologies, School of Medicine, University of Naples “Federico II”, 80131 Naples, Italy; (D.P.); (V.M.); (F.C.); (R.A.)
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Multi-Gene Next-Generation Sequencing for Molecular Diagnosis of Autosomal Recessive Congenital Ichthyosis: A Genotype-Phenotype Study of Four Italian Patients. Diagnostics (Basel) 2020; 10:diagnostics10120995. [PMID: 33255364 PMCID: PMC7760754 DOI: 10.3390/diagnostics10120995] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 11/13/2020] [Accepted: 11/21/2020] [Indexed: 02/06/2023] Open
Abstract
Autosomal recessive congenital ichthyoses (ARCI) are rare genodermatosis disorders characterized by phenotypic and genetic heterogeneity. At least fourteen genes so far have been related to ARCI; however, despite genetic heterogeneity, phenotypes associated with mutation of different ARCI genes may overlap, thereby making difficult their clinical and molecular classification. In addition, molecular tests for diagnosis of such an extremely rare heterogeneous inherited disease are not easily available in clinical settings. In the attempt of identifying the genetic cause of the disease in four Italian patients with ARCI, we performed next-generation sequencing (NGS) analysis targeting 4811 genes that have been previously linked to human genetic diseases; we focused our analysis on the 13 known ARCI genes comprised in the panel. Nine different variants including three novel small nucleotide changes and two novel large deletions have been identified and validated in the ABCA12, ALOX12B, CYP4F22, and SULT2B1 genes. Notably, two patients had variants in more than one gene. The identification and validation of new pathogenic ABCA12, ALOX12B, CYP4F22, and SULT2B1 variants through multi-gene NGS in four cases of ARCI further highlight the importance of these genes in proper skin function and development.
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Marukian NV, Hu RH, Craiglow BG, Milstone LM, Zhou J, Theos A, Kaymakcalan H, Akkaya DA, Uitto JJ, Vahidnezhad H, Youssefian L, Bayliss SJ, Paller AS, Boyden LM, Choate KA. Expanding the Genotypic Spectrum of Bathing Suit Ichthyosis. JAMA Dermatol 2017; 153:537-543. [PMID: 28403434 DOI: 10.1001/jamadermatol.2017.0202] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Importance Bathing suit ichthyosis (BSI) is a rare congenital disorder of keratinization characterized by restriction of scale to sites of relatively higher temperature such as the trunk, with cooler areas remaining unaffected. Fewer than 40 cases have been reported in the literature. Bathing suit ichthyosis is caused by recessive, temperature-sensitive mutations in the transglutaminase-1 gene (TGM1). Clear genotype-phenotype correlations have been difficult to establish because several of the same TGM1 mutations have been reported in BSI and other forms of congenital ichthyosis. We identify novel and recurrent mutations in 16 participants with BSI. Objective To expand the genotypic spectrum of BSI, identifying novel TGM1 mutations in patients with BSI, and to use BSI genotypes to draw inferences about the temperature sensitivity of TGM1 mutations. Design, Setting, and Participants A total of 16 participants with BSI from 13 kindreds were identified from 6 academic medical centers. A detailed clinical history was obtained from each participant, including phenotypic presentation at birth and disease course. Each participant underwent targeted sequencing of TGM1. Main Outcomes and Measures Phenotypic and genotypic characteristics in these patients from birth onward. Results Of the 16 participants, 7 were male, and 9 were female (mean age, 12.6 years; range, 1-39 years). We found 1 novel TGM1 indel mutation (Ile469_Cys471delinsMetLeu) and 8 TGM1 missense mutations that to our knowledge have not been previously reported in BSI: 5 have been previously described in non-temperature-sensitive forms of congenital ichthyosis (Arg143Cys, Gly218Ser, Gly278Arg, Arg286Gln, and Ser358Arg), and 3 (Tyr374Cys, Phe495Leu, and Ser772Arg) are novel mutations. Three probands were homozygous for Arg264Trp, Arg286Gln, or Arg315Leu, indicating that these mutations are temperature sensitive. Seven of 10 probands with a compound heterozygous TGM1 genotype had a mutation at either arginine 307 or 315, providing evidence that mutations at these sites are temperature sensitive and highlighting the importance of these residues in the pathogenesis of BSI. Conclusions and Relevance Our findings expand the genotypic spectrum of BSI and the understanding of temperature sensitivity of TGM1 mutations. Increased awareness of temperature-sensitive TGM1 genotypes should aid in genetic counseling and provide insights into the pathophysiology of TGM1 ichthyoses, transglutaminase-1 enzymatic activity, and potential therapeutic approaches.
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Affiliation(s)
- Nareh V Marukian
- Department of Dermatology, Yale University School of Medicine, New Haven, Connecticut
| | - Rong-Hua Hu
- Department of Dermatology, Yale University School of Medicine, New Haven, Connecticut
| | - Brittany G Craiglow
- Department of Dermatology, Yale University School of Medicine, New Haven, Connecticut2Department of Pediatrics, Yale University School of Medicine, New Haven, Connecticut
| | - Leonard M Milstone
- Department of Dermatology, Yale University School of Medicine, New Haven, Connecticut
| | - Jing Zhou
- Department of Dermatology, Yale University School of Medicine, New Haven, Connecticut
| | - Amy Theos
- Department of Dermatology, University of Alabama School of Medicine, Birmingham
| | - Hande Kaymakcalan
- Department of Pediatrics, Istanbul Bilim University, Istanbul, Turkey
| | - Deniz A Akkaya
- Department of Dermatology, Koç University Hospital, Istanbul, Turkey6Department of Dermatology, V.K.F American Hospital of Istanbul, Istanbul, Turkey
| | - Jouni J Uitto
- Department of Dermatology, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Hassan Vahidnezhad
- Department of Dermatology, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Leila Youssefian
- Department of Dermatology, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Susan J Bayliss
- Division of Dermatology, Department of Medicine, Washington University School of Medicine, St Louis, Missouri
| | - Amy S Paller
- Department of Dermatology, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - Lynn M Boyden
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut
| | - Keith A Choate
- Department of Dermatology, Yale University School of Medicine, New Haven, Connecticut10Department of Genetics, Yale University School of Medicine, New Haven, Connecticut11Department of Pathology, Yale University School of Medicine, New Haven, Connecticut
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Esposito G, De Falco F, Neri I, Graziano C, Toschi B, Auricchio L, Gouveia C, Sousa AB, Salvatore F. Different TGM1 mutation spectra in Italian and Portuguese patients with autosomal recessive congenital ichthyosis: evidence of founder effects in Portugal. Br J Dermatol 2013; 168:1364-7. [PMID: 23278109 DOI: 10.1111/bjd.12179] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Akiyama M, Sakai K, Yanagi T, Fukushima S, Ihn H, Hitomi K, Shimizu H. Transglutaminase1 preferred substrate peptide K5 is an efficient tool in diagnosis of lamellar ichthyosis. THE AMERICAN JOURNAL OF PATHOLOGY 2010; 176:1592-9. [PMID: 20167857 DOI: 10.2353/ajpath.2010.090597] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Lamellar ichthyosis (LI) is a genetically heterogeneous, severe genodermatosis showing widespread hyperkeratosis of the skin. Transglutaminase 1 (TGase1) deficiency by TGase1 gene (TGM1) mutations is the most prevalent cause of LI. Screening of TGase1 deficiency in skin is essential to facilitate the molecular diagnosis of LI. However, cadaverine, the most widely used substrate for TGase activity assay, is not isozyme specific. Recently, a human TGase1-specific highly preferred substrate peptide K5 (pepK5) was generated. To evaluate its potential as a diagnostic tool for LI, we performed pepK5 labeling of TGase1 activity in normal human and LI skin. Ca(2+)-dependent labeling of FITC-pepK5 was clearly seen in the upper spinous and granular layers of normal human skin where it precisely overlapped with TGase1 immunostaining. Both specificity and sensitivity of FITC-pepK5 labeling for TGase1 activity were higher than those of FITC-cadaverine labeling. FITC-pepK5 labeling colocalized with involucrin and loricrin immunostaining at cornified cell envelope forming sites. FITC-pepK5 labeling was negative in LI patients carrying TGM1 truncation mutations and partially abolished in the other LI patients harboring missense mutations. The present results clearly indicate that pepK5 is a powerful tool for screening LI patient TGase1 deficiency when we make molecular diagnosis of LI.
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Affiliation(s)
- Masashi Akiyama
- Department of Dermatology, Hokkaido University Graduate School of Medicine, Sapporo 060-8638, Japan.
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Chiavérini C. Ichtyoses génétiques. Ann Dermatol Venereol 2009; 136:923-34. [DOI: 10.1016/j.annder.2009.01.021] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2008] [Accepted: 01/23/2009] [Indexed: 01/07/2023]
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Turgut B, Aydemir O, Kaya M, Türkçüoğlu P, Demir T, Celiker U. Spontaneous corneal perforation in a patient with lamellar ichthyosis and dry eye. Clin Ophthalmol 2009; 3:611-3. [PMID: 19997563 PMCID: PMC2788586 DOI: 10.2147/opth.s8407] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2009] [Indexed: 11/23/2022] Open
Abstract
We report spontaneous corneal perforation in a patient with lamellar ichthyosis. The patient presented with complaints of pain, redness, diminished vision, and discharge in her right eye for 15 days. Visual acuities were light perception in the right and 20/400 in the left eye. Cicatricial ectropion in both lower eyelids and 2 mm perforation site in the center of the right cornea were observed. Lamellar ichthyosis was suspected because of scaling and excessive dryness of entire body skin and was confirmed by skin biopsy. Amniotic membrane transplantation and transient tarsorraphy was performed and systemic anti-ichthyosis therapy was started. The follow-up visits were not possible because of patient inconsistency. In patients with cicatricial ectropion secondary to ichthyosis, corneal health should be closely monitored because of the perforation risk.
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Affiliation(s)
- Burak Turgut
- Firat University School of Medicine, Department of Ophthalmology, Elaziğ, Turkey.
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Autosomal recessive congenital ichthyosis and congenital hypothyroidism in a Tunisian patient with a nonsense mutation in TGM1. J Dermatol Sci 2009; 55:128-30. [DOI: 10.1016/j.jdermsci.2009.05.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2009] [Revised: 05/11/2009] [Accepted: 05/15/2009] [Indexed: 11/19/2022]
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Herman ML, Farasat S, Steinbach PJ, Wei MH, Toure O, Fleckman P, Blake P, Bale SJ, Toro JR. Transglutaminase-1 gene mutations in autosomal recessive congenital ichthyosis: summary of mutations (including 23 novel) and modeling of TGase-1. Hum Mutat 2009; 30:537-47. [PMID: 19241467 PMCID: PMC3243309 DOI: 10.1002/humu.20952] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Autosomal recessive congenital ichthyosis (ARCI) is a heterogeneous group of rare cornification diseases. Germline mutations in TGM1 are the most common cause of ARCI in the United States. TGM1 encodes for the TGase-1 enzyme that functions in the formation of the cornified cell envelope. Structurally defective or attenuated cornified cell envelop have been shown in epidermal scales and appendages of ARCI patients with TGM1 mutations. We review the clinical manifestations as well as the molecular genetics of ARCI. In addition, we characterized 115 TGM1 mutations reported in 234 patients from diverse racial and ethnic backgrounds (Caucasion Americans, Norwegians, Swedish, Finnish, German, Swiss, French, Italian, Dutch, Portuguese, Hispanics, Iranian, Tunisian, Moroccan, Egyptian, Afghani, Hungarian, African Americans, Korean, Japanese and South African). We report 23 novel mutations: 71 (62%) missense; 20 (17%) nonsense; 9 (8%) deletion; 8 (7%) splice-site, and 7 (6%) insertion. The c.877-2A>G was the most commonly reported TGM1 mutation accounting for 34% (147 of 435) of all TGM1 mutant alleles reported to date. It had been shown that this mutation is common among North American and Norwegian patients due to a founder effect. Thirty-one percent (36 of 115) of all mutations and 41% (29 of 71) of missense mutations occurred in arginine residues in TGase-1. Forty-nine percent (35 of 71) of missense mutations were within CpG dinucleotides, and 74% (26/35) of these mutations were C>T or G>A transitions. We constructed a model of human TGase-1 and showed that all mutated arginines that reside in the two beta-barrel domains and two (R142 and R143) in the beta-sandwich are located at domain interfaces. In conclusion, this study expands the TGM1 mutation spectrum and summarizes the current knowledge of TGM1 mutations. The high frequency of mutated arginine codons in TGM1 may be due to the deamination of 5' methylated CpG dinucleotides.
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Affiliation(s)
- Matthew L. Herman
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, Rockville, MD 20892, USA
| | - Sharifeh Farasat
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, Rockville, MD 20892, USA
| | - Peter J. Steinbach
- Center for Molecular Modeling, Division of Computational Bioscience, Center for Information Technology, NIH, Bethesda, MD, 20892, USA
| | - Ming-Hui Wei
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, Rockville, MD 20892, USA
- Basic Research Program, SAIC-Frederick Inc., Frederick, MD 21702, USA
| | - Ousmane Toure
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, Rockville, MD 20892, USA
| | - Philip Fleckman
- Division of Dermatology, Department of Medicine, University of Washington, Seattle, WA, 98195, USA
| | - Patrick Blake
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, Rockville, MD 20892, USA
- Howard Hughes Medical Institute, Chevy Chase, MD
| | | | - Jorge R. Toro
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, Rockville, MD 20892, USA
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Farasat S, Wei MH, Herman M, Liewehr DJ, Steinberg SM, Bale SJ, Fleckman P, Toro JR. Novel transglutaminase-1 mutations and genotype-phenotype investigations of 104 patients with autosomal recessive congenital ichthyosis in the USA. J Med Genet 2008; 46:103-11. [PMID: 18948357 DOI: 10.1136/jmg.2008.060905] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BACKGROUND Autosomal recessive congenital ichthyosis (ARCI) is a rare hereditary disorder of cornification. Mutations in the transglutaminase-1 (TGM1) gene, which encodes for the epidermal enzyme transglutaminase-1 (TGase-1), are one of the causes of ARCI. METHODS The TGM1 mutation spectrum was characterised and genotype-phenotype correlations investigated in 104 patients with ARCI ascertained through the National Registry for Ichthyosis and Related Disorders in the USA. Methods: Germline mutations in TGM1 were identified in 55% (57/104) of patients with ARCI. Arginine residues in TGase-1 were mutated in 39% (22/57) of patients overall and 54% (20/37) of those with missense mutations. In total, 55% (12/22) of missense mutations were within CpG dinucleotides and 92% (11/12) of these mutations were C-->T or G-->A transitions. The genotype-phenotype investigation found that ARCI with TGM1 mutations was significantly associated with presence of collodion membrane at birth (p = 0.006), ectropion (p = 0.001), plate-like scales (p = 0.005) and alopecia (p = 0.001). Patients who had at least one mutation predicted to truncate TGase-1 were more likely to have more severe hypohidrosis (p = 0.001) and overheating (p = 0.0007) at onset of symptoms than were those with exclusively TGM1 missense mutations. A logistic model was developed, which predicted that individuals with collodion membrane, alopecia and/or eye problems are about four times more likely to have TGM1 mutations than patients without these findings. CONCLUSION This is the largest investigation of patients with ARCI to date. It expands the TGM1 mutation spectrum and confirms that despite genetic and phenotypic heterogeneity in ARCI, TGM1 is the main causative gene for this disorder. The high frequency of mutated arginine codons in TGM1 may be due to the deamination of CpG dinucleotides.
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Affiliation(s)
- S Farasat
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, 6120 Executive Boulevard, Rockville, MD 20892-4562, USA
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