A 6 NUCLEOTIDE IN FRAME DUPLICATION IN PIEZO1 GENE IN TWO FAMILIES WITH DEHYDRATED HEREDITARY STOMATOCYTOSIS
(Abstract release date: 05/19/16)
EHA Library. Andolfo I. 06/09/16; 133013; E1464
Disclosure(s): No conflict of interest to disclose
Dr. Immacolata Andolfo
Contributions
Contributions
Abstract
Abstract: E1464
Type: Eposter Presentation
Background
Dehydrated hereditary stomatocytosis (DHSt), also known as hereditary xerocytosis, is an autosomal dominant congenital hemolytic anemia associated with a monovalent cation leak. DHSt consists of an usually compensated hemolysis, associated with moderate splenomegaly. Blood smears show variable numbers of stomatocytes, elevated reticulocyte count and a slightly increased red cell mean corpuscular volume (MCV). DHSt red blood cells (RBCs) exhibit decreased intraerythrocytic K+ content and increased intraerythrocytic Na+ content.The causative gene of this condition was recently identified in the FAM38A gene encoding the mechanosensitive cation channel, PIEZO1 (Andolfo I., et al, 2013; Zarychanski R., et al, 2012). Several functional characterizations of identified PIEZO1 mutations in DHSt families have uniformly demonstrated gain-of-function properties consistent with the increased net ion fluxes leading to DHSt (Andolfo I., et al, 2013; Albuisson J, et al, 2013; Bae C., et al, 2013).Recently, a new causative gene of DHSt was identified in the KCNN4 gene encoding the Gardos channel (Andolfo I., et al, 2015; Raphael R-M, et al, 2015; Glogowska E., et al, 2015). The Gardos channel/KCNN4 is a widely expressed Ca2+-dependent K+ channel that mediates the major K+ conductance of erythrocytes (Begenisich T, et al, 2004).
Aims
In this study we performed osmotic gradient ektacytometry and DNA sequence analysis of PIEZO1/KCNN4 genes in seven patients with clinical suspicion of DHSt from two unrelated families (family 1 and family 2) to assess the clinical diagnosis.
Methods
Deformability of the RBCs of the patients and relative control subjects were evaluated by osmotic gradient ektacytometry using the Laser-assisted Optical Rotational Cell Analyzer (LORCA). Genomic mutational screening was performed by direct sequencing analysis, as previously described (Andolfo I., et al, 2013).
Results
Ektacytometric analyses showed a leftward shift of the bell-shaped curve for all the patients in respect to the healthy controls indicating dehydration of the RBCs.Subsequently, DNA analysis of the patients revealed no mutations in KCNN4 gene and the mutation c.7473_7478dupGGAGCT, p.Glu2492_Leu2493dup in PIEZO1 gene that cosegregated with the disease phenotypes in both the families. Both Glu2492 and Leu2493 residues are highly conserved in PIEZO1 (http://genome.ucsc.edu/). Interestingly, the duplication is localized in the C-terminal domain of the protein that was recently identified as the pore of the mechanosensitive cation channel.Moreover, the proband of the family 1 showed another de novo PIEZO1 mutation c.5591G>A, p.Arg1864His in cis with the duplication p.Glu2492_Leu2493dup. Of note, the proband presents a more severe clinical phenotype when compared to that observed in his affected father.
Conclusion
Molecular characterization of seven DHSt patients from two unrelated families revealed a novel in frame duplication and a novel missense mutation in PIEZO1 gene. We are currently performing a functional study to evaluate the causative role of both novel mutations here described. Particularly, we are characterizing the possible modifier role of the de novo mutation, p.Arg1864His, in cis with the inherited duplication on the occurrence of severe phenotype observed in the proband of family 1.
Session topic: E-poster
Keyword(s): Anemia, Genetic, Genetic modifiers, Red blood cell
Type: Eposter Presentation
Background
Dehydrated hereditary stomatocytosis (DHSt), also known as hereditary xerocytosis, is an autosomal dominant congenital hemolytic anemia associated with a monovalent cation leak. DHSt consists of an usually compensated hemolysis, associated with moderate splenomegaly. Blood smears show variable numbers of stomatocytes, elevated reticulocyte count and a slightly increased red cell mean corpuscular volume (MCV). DHSt red blood cells (RBCs) exhibit decreased intraerythrocytic K+ content and increased intraerythrocytic Na+ content.The causative gene of this condition was recently identified in the FAM38A gene encoding the mechanosensitive cation channel, PIEZO1 (Andolfo I., et al, 2013; Zarychanski R., et al, 2012). Several functional characterizations of identified PIEZO1 mutations in DHSt families have uniformly demonstrated gain-of-function properties consistent with the increased net ion fluxes leading to DHSt (Andolfo I., et al, 2013; Albuisson J, et al, 2013; Bae C., et al, 2013).Recently, a new causative gene of DHSt was identified in the KCNN4 gene encoding the Gardos channel (Andolfo I., et al, 2015; Raphael R-M, et al, 2015; Glogowska E., et al, 2015). The Gardos channel/KCNN4 is a widely expressed Ca2+-dependent K+ channel that mediates the major K+ conductance of erythrocytes (Begenisich T, et al, 2004).
Aims
In this study we performed osmotic gradient ektacytometry and DNA sequence analysis of PIEZO1/KCNN4 genes in seven patients with clinical suspicion of DHSt from two unrelated families (family 1 and family 2) to assess the clinical diagnosis.
Methods
Deformability of the RBCs of the patients and relative control subjects were evaluated by osmotic gradient ektacytometry using the Laser-assisted Optical Rotational Cell Analyzer (LORCA). Genomic mutational screening was performed by direct sequencing analysis, as previously described (Andolfo I., et al, 2013).
Results
Ektacytometric analyses showed a leftward shift of the bell-shaped curve for all the patients in respect to the healthy controls indicating dehydration of the RBCs.Subsequently, DNA analysis of the patients revealed no mutations in KCNN4 gene and the mutation c.7473_7478dupGGAGCT, p.Glu2492_Leu2493dup in PIEZO1 gene that cosegregated with the disease phenotypes in both the families. Both Glu2492 and Leu2493 residues are highly conserved in PIEZO1 (http://genome.ucsc.edu/). Interestingly, the duplication is localized in the C-terminal domain of the protein that was recently identified as the pore of the mechanosensitive cation channel.Moreover, the proband of the family 1 showed another de novo PIEZO1 mutation c.5591G>A, p.Arg1864His in cis with the duplication p.Glu2492_Leu2493dup. Of note, the proband presents a more severe clinical phenotype when compared to that observed in his affected father.
Conclusion
Molecular characterization of seven DHSt patients from two unrelated families revealed a novel in frame duplication and a novel missense mutation in PIEZO1 gene. We are currently performing a functional study to evaluate the causative role of both novel mutations here described. Particularly, we are characterizing the possible modifier role of the de novo mutation, p.Arg1864His, in cis with the inherited duplication on the occurrence of severe phenotype observed in the proband of family 1.
Session topic: E-poster
Keyword(s): Anemia, Genetic, Genetic modifiers, Red blood cell
Abstract: E1464
Type: Eposter Presentation
Background
Dehydrated hereditary stomatocytosis (DHSt), also known as hereditary xerocytosis, is an autosomal dominant congenital hemolytic anemia associated with a monovalent cation leak. DHSt consists of an usually compensated hemolysis, associated with moderate splenomegaly. Blood smears show variable numbers of stomatocytes, elevated reticulocyte count and a slightly increased red cell mean corpuscular volume (MCV). DHSt red blood cells (RBCs) exhibit decreased intraerythrocytic K+ content and increased intraerythrocytic Na+ content.The causative gene of this condition was recently identified in the FAM38A gene encoding the mechanosensitive cation channel, PIEZO1 (Andolfo I., et al, 2013; Zarychanski R., et al, 2012). Several functional characterizations of identified PIEZO1 mutations in DHSt families have uniformly demonstrated gain-of-function properties consistent with the increased net ion fluxes leading to DHSt (Andolfo I., et al, 2013; Albuisson J, et al, 2013; Bae C., et al, 2013).Recently, a new causative gene of DHSt was identified in the KCNN4 gene encoding the Gardos channel (Andolfo I., et al, 2015; Raphael R-M, et al, 2015; Glogowska E., et al, 2015). The Gardos channel/KCNN4 is a widely expressed Ca2+-dependent K+ channel that mediates the major K+ conductance of erythrocytes (Begenisich T, et al, 2004).
Aims
In this study we performed osmotic gradient ektacytometry and DNA sequence analysis of PIEZO1/KCNN4 genes in seven patients with clinical suspicion of DHSt from two unrelated families (family 1 and family 2) to assess the clinical diagnosis.
Methods
Deformability of the RBCs of the patients and relative control subjects were evaluated by osmotic gradient ektacytometry using the Laser-assisted Optical Rotational Cell Analyzer (LORCA). Genomic mutational screening was performed by direct sequencing analysis, as previously described (Andolfo I., et al, 2013).
Results
Ektacytometric analyses showed a leftward shift of the bell-shaped curve for all the patients in respect to the healthy controls indicating dehydration of the RBCs.Subsequently, DNA analysis of the patients revealed no mutations in KCNN4 gene and the mutation c.7473_7478dupGGAGCT, p.Glu2492_Leu2493dup in PIEZO1 gene that cosegregated with the disease phenotypes in both the families. Both Glu2492 and Leu2493 residues are highly conserved in PIEZO1 (http://genome.ucsc.edu/). Interestingly, the duplication is localized in the C-terminal domain of the protein that was recently identified as the pore of the mechanosensitive cation channel.Moreover, the proband of the family 1 showed another de novo PIEZO1 mutation c.5591G>A, p.Arg1864His in cis with the duplication p.Glu2492_Leu2493dup. Of note, the proband presents a more severe clinical phenotype when compared to that observed in his affected father.
Conclusion
Molecular characterization of seven DHSt patients from two unrelated families revealed a novel in frame duplication and a novel missense mutation in PIEZO1 gene. We are currently performing a functional study to evaluate the causative role of both novel mutations here described. Particularly, we are characterizing the possible modifier role of the de novo mutation, p.Arg1864His, in cis with the inherited duplication on the occurrence of severe phenotype observed in the proband of family 1.
Session topic: E-poster
Keyword(s): Anemia, Genetic, Genetic modifiers, Red blood cell
Type: Eposter Presentation
Background
Dehydrated hereditary stomatocytosis (DHSt), also known as hereditary xerocytosis, is an autosomal dominant congenital hemolytic anemia associated with a monovalent cation leak. DHSt consists of an usually compensated hemolysis, associated with moderate splenomegaly. Blood smears show variable numbers of stomatocytes, elevated reticulocyte count and a slightly increased red cell mean corpuscular volume (MCV). DHSt red blood cells (RBCs) exhibit decreased intraerythrocytic K+ content and increased intraerythrocytic Na+ content.The causative gene of this condition was recently identified in the FAM38A gene encoding the mechanosensitive cation channel, PIEZO1 (Andolfo I., et al, 2013; Zarychanski R., et al, 2012). Several functional characterizations of identified PIEZO1 mutations in DHSt families have uniformly demonstrated gain-of-function properties consistent with the increased net ion fluxes leading to DHSt (Andolfo I., et al, 2013; Albuisson J, et al, 2013; Bae C., et al, 2013).Recently, a new causative gene of DHSt was identified in the KCNN4 gene encoding the Gardos channel (Andolfo I., et al, 2015; Raphael R-M, et al, 2015; Glogowska E., et al, 2015). The Gardos channel/KCNN4 is a widely expressed Ca2+-dependent K+ channel that mediates the major K+ conductance of erythrocytes (Begenisich T, et al, 2004).
Aims
In this study we performed osmotic gradient ektacytometry and DNA sequence analysis of PIEZO1/KCNN4 genes in seven patients with clinical suspicion of DHSt from two unrelated families (family 1 and family 2) to assess the clinical diagnosis.
Methods
Deformability of the RBCs of the patients and relative control subjects were evaluated by osmotic gradient ektacytometry using the Laser-assisted Optical Rotational Cell Analyzer (LORCA). Genomic mutational screening was performed by direct sequencing analysis, as previously described (Andolfo I., et al, 2013).
Results
Ektacytometric analyses showed a leftward shift of the bell-shaped curve for all the patients in respect to the healthy controls indicating dehydration of the RBCs.Subsequently, DNA analysis of the patients revealed no mutations in KCNN4 gene and the mutation c.7473_7478dupGGAGCT, p.Glu2492_Leu2493dup in PIEZO1 gene that cosegregated with the disease phenotypes in both the families. Both Glu2492 and Leu2493 residues are highly conserved in PIEZO1 (http://genome.ucsc.edu/). Interestingly, the duplication is localized in the C-terminal domain of the protein that was recently identified as the pore of the mechanosensitive cation channel.Moreover, the proband of the family 1 showed another de novo PIEZO1 mutation c.5591G>A, p.Arg1864His in cis with the duplication p.Glu2492_Leu2493dup. Of note, the proband presents a more severe clinical phenotype when compared to that observed in his affected father.
Conclusion
Molecular characterization of seven DHSt patients from two unrelated families revealed a novel in frame duplication and a novel missense mutation in PIEZO1 gene. We are currently performing a functional study to evaluate the causative role of both novel mutations here described. Particularly, we are characterizing the possible modifier role of the de novo mutation, p.Arg1864His, in cis with the inherited duplication on the occurrence of severe phenotype observed in the proband of family 1.
Session topic: E-poster
Keyword(s): Anemia, Genetic, Genetic modifiers, Red blood cell
{{ help_message }}
{{filter}}