Hereditary myeloperoxidase deficiency (MPOD; #254600) is characterised by decreased or completely absent myeloperoxidase activity in neutrophils and monocytes. The disorder is caused by mutations occurring in the MPO gene.1–3 In humans, the disorder is not uncommon with an estimated frequency of 1/1000 to 1/4000 people.4 Myeloperoxidase (EC 1.11.2.2) contributes to host innate immunity, and MPOD in humans and in a mouse model has been associated with an increased susceptibility to certain fungal infections and, in particular, to disseminated Candida albicans infection.5–9 During routine examinations, we identified a 12-year-old Italian hound dog from the local dog shelter that despite the absence of any evident symptoms of the underlying disease showed primary MPOD in the polymorphonuclear leucocytes and monocytes. This was evident from a complete blood count on an ADVIA 2120 Siemens Analyser with automated MPO staining for differentiation of white blood cells. In typical staining scattergrams, MPO-positive cells, such as neutrophils and monocytes, are clustered within specified areas demarcated by thresholds. The affected dog showed a scattergram typical for MPOD deficiency in humans with all white blood cells consistently aligned on the left in the large unstained cell area. To confirm the diagnosis, the complete blood count was repeated once a month for three consecutive months with identical findings (Fig. 1). (CANFA) MPO messenger RNA was purified from blood and reverse-transcribed using SuperScript III Reverse Transcriptase (Invitrogen). Overlapping gene fragments were amplified and forward- and reverse-sequenced. Comparison of the (CANFA) MPO sequences from the affected dog, from a normal dog and from two predicted MPO splice variants allowed the identification of a homozygous c.1987C>T (Ensembl transcript ID: ENSCAFT00000027699) or c.1753C>T (Ensembl transcript ID: ENSCAFT00000049922) substitution, which results in a premature termination codon (p.663Arg*) in the superoxide domain (Fig. S1, Accession number KX017977). The mutation was confirmed by sequencing of a PCR fragment with genomic DNA purified from blood as template (Table S1). Expression of mRNA level in the MPOD dog was substantially lowerthan in the control, which may be explained by a nonsense- mediated decay system (Fig. S2). This is the first description of hereditary MPOD in a dog and its causative mutation. Hereditary myeloperoxidase deficiencyaffected dogs may represent a reliable spontaneous animal model of the human counterpart as an alternative to knockout mice.5–8,10

A nonsense mutation in the myeloperoxidase gene is responsible for hereditary myeloperoxidase deficiency in an Italian hound dog

GENTILINI, FABIO;
2016

Abstract

Hereditary myeloperoxidase deficiency (MPOD; #254600) is characterised by decreased or completely absent myeloperoxidase activity in neutrophils and monocytes. The disorder is caused by mutations occurring in the MPO gene.1–3 In humans, the disorder is not uncommon with an estimated frequency of 1/1000 to 1/4000 people.4 Myeloperoxidase (EC 1.11.2.2) contributes to host innate immunity, and MPOD in humans and in a mouse model has been associated with an increased susceptibility to certain fungal infections and, in particular, to disseminated Candida albicans infection.5–9 During routine examinations, we identified a 12-year-old Italian hound dog from the local dog shelter that despite the absence of any evident symptoms of the underlying disease showed primary MPOD in the polymorphonuclear leucocytes and monocytes. This was evident from a complete blood count on an ADVIA 2120 Siemens Analyser with automated MPO staining for differentiation of white blood cells. In typical staining scattergrams, MPO-positive cells, such as neutrophils and monocytes, are clustered within specified areas demarcated by thresholds. The affected dog showed a scattergram typical for MPOD deficiency in humans with all white blood cells consistently aligned on the left in the large unstained cell area. To confirm the diagnosis, the complete blood count was repeated once a month for three consecutive months with identical findings (Fig. 1). (CANFA) MPO messenger RNA was purified from blood and reverse-transcribed using SuperScript III Reverse Transcriptase (Invitrogen). Overlapping gene fragments were amplified and forward- and reverse-sequenced. Comparison of the (CANFA) MPO sequences from the affected dog, from a normal dog and from two predicted MPO splice variants allowed the identification of a homozygous c.1987C>T (Ensembl transcript ID: ENSCAFT00000027699) or c.1753C>T (Ensembl transcript ID: ENSCAFT00000049922) substitution, which results in a premature termination codon (p.663Arg*) in the superoxide domain (Fig. S1, Accession number KX017977). The mutation was confirmed by sequencing of a PCR fragment with genomic DNA purified from blood as template (Table S1). Expression of mRNA level in the MPOD dog was substantially lowerthan in the control, which may be explained by a nonsense- mediated decay system (Fig. S2). This is the first description of hereditary MPOD in a dog and its causative mutation. Hereditary myeloperoxidase deficiencyaffected dogs may represent a reliable spontaneous animal model of the human counterpart as an alternative to knockout mice.5–8,10
Gentilini, Fabio; Zambon, Elisa; Mancini, Danilo; Turba, Maria Elena
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/587393
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