Browsing by Author "Potchanant, Elizabeth Sierra"

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    FANCA safeguards interphase and mitosis during hematopoiesis in vivo
    (Elsevier, 2015-12) Abdul-Sater, Zahi; Cerabona, Donna; Potchanant, Elizabeth Sierra; Sun, Zejin; Enzor, Rikki; He, Ying; Robertson, Kent; Goebel, W. Scott; Nalepa, Grzegorz; Department of Pediatrics, IU School of Medicine
    The Fanconi anemia (FA/BRCA) signaling network controls multiple genome-housekeeping checkpoints, from interphase DNA repair to mitosis. The in vivo role of abnormal cell division in FA remains unknown. Here, we quantified the origins of genomic instability in FA patients and mice in vivo and ex vivo. We found that both mitotic errors and interphase DNA damage significantly contribute to genomic instability during FA-deficient hematopoiesis and in nonhematopoietic human and murine FA primary cells. Super-resolution microscopy coupled with functional assays revealed that FANCA shuttles to the pericentriolar material to regulate spindle assembly at mitotic entry. Loss of FA signaling rendered cells hypersensitive to spindle chemotherapeutics and allowed escape from the chemotherapy-induced spindle assembly checkpoint. In support of these findings, direct comparison of DNA crosslinking and anti-mitotic chemotherapeutics in primary FANCA-/- cells revealed genomic instability originating through divergent cell cycle checkpoint aberrations. Our data indicate that FA/BRCA signaling functions as an in vivo gatekeeper of genomic integrity throughout interphase and mitosis, which may have implications for future targeted therapies in FA and FA-deficient cancers.
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    Whole-exome sequencing enables correct diagnosis and surgical management of rare inherited childhood anemia
    (Cold Spring Harbor Laboratory Press, 2018-10-01) Khurana, Monica; Edwards, Donna; Rescorla, Frederic; Miller, Caroline; He, Ying; Potchanant, Elizabeth Sierra; Nalepa, Grzegorz; Pediatrics, School of Medicine
    Correct diagnosis of inherited bone marrow failure syndromes is a challenge because of the significant overlap in clinical presentation of these disorders. Establishing right genetic diagnosis is crucial for patients' optimal clinical management and family counseling. A nondysmorphic infant reported here developed severe transfusion-dependent anemia and met clinical criteria for diagnosis of Diamond-Blackfan anemia (DBA). However, whole-exome sequencing demonstrated that the child was a compound heterozygote for a paternally inherited pathogenic truncating variant (SPTA1 c.4975 C>T) and a novel maternally inherited missense variant of uncertain significance (SPTA1 c.5029 G>A) within the spectrin gene, consistent with hereditary hemolytic anemia due to disruption of red blood cell (RBC) cytoskeleton. Ektacytometry demonstrated abnormal membrane flexibility of the child's RBCs. Scanning electron microscopy revealed morphological aberrations of the patient's RBCs. Both parents were found to have mild hereditary elliptocytosis. Importantly, patients with severe RBC membrane defects may be successfully managed with splenectomy to minimize peripheral destruction of misshapen RBCs, whereas patients with DBA require lifelong transfusions, steroid therapy, or hematopoietic stem cell transplantation. As suggested by the WES findings, splenectomy rendered our patient transfusion-independent, improving the family's quality of life and preventing transfusion-related iron overload. This case illustrates the utility of whole-exome sequencing in clinical care of children with genetic disorders of unclear presentation.