Katariina Hannula-Jouppi1, Satu-Leena Laasanen2, Mette Ilander3, Laetitia Furio4, Mirja Tuomiranta5, Riitta Marttila6, Leila Jeskanen7, Valtteri Häyry8, Mervi Kanerva8, Sirpa Kivirikko9, Marja-Leena Tuomi2, Hannele Heikkilä7, Satu Mustjoki3, Alain Hovnanian10, Annamari Ranki7. 1. Department of Dermatology and Allergology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland2Folkhälsan Institute of Genetics, University of Helsinki, Helsinki, Finland. 2. Department of Dermatology, Tampere University Hospital, Tampere, Finland. 3. Hematology Research Unit Helsinki, Department of Clinical Chemistry and Hematology, University of Helsinki and Helsinki University Hospital Comprehensive Cancer Center, Helsinki, Finland. 4. Laboratory of Genetic Skin Diseases, Institut National de la Santé et de la Recherche Medicale, Unité Mixte de Recherche 1163, Paris, France6Imagine Institute, Paris Descartes University-Sorbonne Paris Cité, Paris, France. 5. Department of Dermatology, Seinäjoki Central Hospital, Seinäjoki, Finland. 6. Department of Pediatrics, Seinäjoki Central Hospital, Seinäjoki, Finland. 7. Department of Dermatology and Allergology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland. 8. Department of Otorhinolaryngology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland. 9. Department of Clinical Genetics, University of Helsinki and Helsinki University Hospital, Helsinki, Finland. 10. Laboratory of Genetic Skin Diseases, Institut National de la Santé et de la Recherche Medicale, Unité Mixte de Recherche 1163, Paris, France6Imagine Institute, Paris Descartes University-Sorbonne Paris Cité, Paris, France11Department of Genetics, Necker H.
Abstract
IMPORTANCE: Netherton syndrome (NS) is a rare and severe genodermatosis caused by SPINK5 mutations leading to the loss of lymphoepithelial Kazal-type-related inhibitor (LEKTI). Netherton syndrome is characterized by neonatal scaling erythroderma, a bamboolike hair defect, a substantial skin barrier defect, and a profound atopic diathesis. Netherton syndrome has been proposed to be a primary immunodeficiency syndrome because of the high frequency of infections. The precise mechanisms underlying the disease are not fully understood. OBJECTIVE: To study the association of the SPINK5 mutation with the NS phenotype and the extent of immunologic deficiencies in NS. DESIGN, SETTING, AND PARTICIPANTS: Relevant tissue samples and follow-up data from 11 patients with NS from 7 families, including 3 multiplex families, were collected, constituting all known patients with NS in Finland. Another patient with NS from a neighboring country was included. Data were collected from August 10, 2011, to February 20, 2015. SPINK5 mutations were sequenced, and thorough clinical evaluation and histopathologic and immunohistochemical evaluations of skin samples were performed. The function of natural killer cells, lymphocyte phenotype, and serum immunoglobulin subclass levels were evaluated. Data analysis was conducted from October 19, 2011, to February 20, 2015. MAIN OUTCOMES AND MEASURES: The nature of SPINK5 mutations and their correlation with phenotypes in Finnish patients with NS, intrafamilial phenotype variations, and the type of immunologic defects in NS were evaluated. RESULTS: Among the 11 Finnish patients with NS (8 male [73%]; 3 female [27%]; mean [SD] age, 30.1 [9.1] years), a Finnish founder mutation c.652C>T (p.Arg218*) in SPINK5 was identified in 10 patients from 6 families who all originated from the same region. Eight patients were homozygotes for this mutation and 2 siblings were compound heterozygotes with a splice site mutation c.1220 + 1G>C (IVS13 + 1 G>C). Phenotypes were comparable, but some intrafamilial and interfamilial variations were noted. Compound heterozygous patients had a milder phenotype and showed residual LEKTI expression. A previously unreported c.1772delT (p.Leu591Glnfs124*) mutation was found in 1 patient with a phenotype similar to the patients homozygous for the founder mutation. The patient from the neighboring country had a distinct phenotype and different mutations. Immunologically, natural killer cells had an immature phenotype and impaired cytotoxicity and degranulation, levels of memory B cells were reduced, and serum IgG4 levels were elevated. Intravenous immunoglobulin treatment has been beneficial in 1 patient with NS. CONCLUSIONS AND RELEVANCE: This report discloses a prevalent SPINK5 founder mutation in Finland and illustrates NS phenotype variability. Our results also point to a possible role of immature immunity in the frequent infections seen in NS.
IMPORTANCE: Netherton syndrome (NS) is a rare and severe genodermatosis caused by SPINK5 mutations leading to the loss of lymphoepithelial Kazal-type-related inhibitor (LEKTI). Netherton syndrome is characterized by neonatal scaling erythroderma, a bamboolike hair defect, a substantial skin barrier defect, and a profound atopic diathesis. Netherton syndrome has been proposed to be a primary immunodeficiency syndrome because of the high frequency of infections. The precise mechanisms underlying the disease are not fully understood. OBJECTIVE: To study the association of the SPINK5 mutation with the NS phenotype and the extent of immunologic deficiencies in NS. DESIGN, SETTING, AND PARTICIPANTS: Relevant tissue samples and follow-up data from 11 patients with NS from 7 families, including 3 multiplex families, were collected, constituting all known patients with NS in Finland. Another patient with NS from a neighboring country was included. Data were collected from August 10, 2011, to February 20, 2015. SPINK5 mutations were sequenced, and thorough clinical evaluation and histopathologic and immunohistochemical evaluations of skin samples were performed. The function of natural killer cells, lymphocyte phenotype, and serum immunoglobulin subclass levels were evaluated. Data analysis was conducted from October 19, 2011, to February 20, 2015. MAIN OUTCOMES AND MEASURES: The nature of SPINK5 mutations and their correlation with phenotypes in Finnish patients with NS, intrafamilial phenotype variations, and the type of immunologic defects in NS were evaluated. RESULTS: Among the 11 Finnish patients with NS (8 male [73%]; 3 female [27%]; mean [SD] age, 30.1 [9.1] years), a Finnish founder mutation c.652C>T (p.Arg218*) in SPINK5 was identified in 10 patients from 6 families who all originated from the same region. Eight patients were homozygotes for this mutation and 2 siblings were compound heterozygotes with a splice site mutation c.1220 + 1G>C (IVS13 + 1 G>C). Phenotypes were comparable, but some intrafamilial and interfamilial variations were noted. Compound heterozygous patients had a milder phenotype and showed residual LEKTI expression. A previously unreported c.1772delT (p.Leu591Glnfs124*) mutation was found in 1 patient with a phenotype similar to the patients homozygous for the founder mutation. The patient from the neighboring country had a distinct phenotype and different mutations. Immunologically, natural killer cells had an immature phenotype and impaired cytotoxicity and degranulation, levels of memory B cells were reduced, and serum IgG4 levels were elevated. Intravenous immunoglobulin treatment has been beneficial in 1 patient with NS. CONCLUSIONS AND RELEVANCE: This report discloses a prevalent SPINK5 founder mutation in Finland and illustrates NS phenotype variability. Our results also point to a possible role of immature immunity in the frequent infections seen in NS.
Authors: Dillon Mintoff; Isabella Borg; Julia Vornweg; Liam Mercieca; Rijad Merdzanic; Johannes Numrich; Susan Aquilina; Nikolai Paul Pace; Judith Fischer Journal: Mol Genet Genomic Med Date: 2021-02-03 Impact factor: 2.183