RESUMO
To identify gene loci associated with steroid-resistant nephrotic syndrome (SRNS), we utilized homozygosity mapping and exome sequencing in a consanguineous pedigree with three affected siblings. High-density genotyping identified three segments of homozygosity spanning 33.6 Mb on chromosomes 5, 10, and 15 containing 296 candidate genes. Exome sequencing identified two homozygous missense variants within the chromosome 15 segment; an A159P substitution in myosin 1E (MYO1E), encoding a podocyte cytoskeletal protein; and an E181K substitution in nei endonuclease VIII-like 1 (NEIL1), encoding a base-excision DNA repair enzyme. Both variants disrupt highly conserved protein sequences and were absent in public databases, 247 healthy controls, and 286 patients with nephrotic syndrome. The MYO1E A159P variant is noteworthy, as it is expected to impair ligand binding and actin interaction in the MYO1E motor domain. The predicted loss of function is consistent with the previous demonstration that Myo1e inactivation produces nephrotic syndrome in mice. Screening 71 additional patients with SRNS, however, did not identify independent NEIL1 or MYO1E mutations, suggesting larger sequencing efforts are needed to uncover which mutation is responsible for the phenotype. Our findings demonstrate the utility of exome sequencing for rapidly identifying candidate genes for human SRNS.
Assuntos
DNA Glicosilases/genética , Análise Mutacional de DNA , Exoma , Miosina Tipo I/genética , Síndrome Nefrótica/congênito , Estudos de Casos e Controles , Cromossomos Humanos Par 15 , DNA Glicosilases/química , Frequência do Gene , Estudos de Associação Genética , Predisposição Genética para Doença , Homozigoto , Humanos , Itália , Modelos Moleculares , Mutação de Sentido Incorreto , Miosina Tipo I/química , Síndrome Nefrótica/genética , Cidade de Nova Iorque , Linhagem , Fenótipo , Conformação Proteica , Relação Estrutura-AtividadeRESUMO
Peripheral T cell lymphomas (PTCLs) are a heterogeneous and poorly understood group of non-Hodgkin lymphomas. Here we combined whole-exome sequencing of 12 tumor-normal DNA pairs, RNA sequencing analysis and targeted deep sequencing to identify new genetic alterations in PTCL transformation. These analyses identified highly recurrent epigenetic factor mutations in TET2, DNMT3A and IDH2 as well as a new highly prevalent RHOA mutation encoding a p.Gly17Val alteration present in 22 of 35 (67%) angioimmunoblastic T cell lymphoma (AITL) samples and in 8 of 44 (18%) PTCL, not otherwise specified (PTCL-NOS) samples. Mechanistically, the RHOA Gly17Val protein interferes with RHOA signaling in biochemical and cellular assays, an effect potentially mediated by the sequestration of activated guanine-exchange factor (GEF) proteins. In addition, we describe new and recurrent, albeit less frequent, genetic defects including mutations in FYN, ATM, B2M and CD58 implicating SRC signaling, impaired DNA damage response and escape from immune surveillance mechanisms in the pathogenesis of PTCL.
Assuntos
Epigênese Genética/genética , Linfoma de Células T Periférico/genética , Proteínas Proto-Oncogênicas c-fyn/genética , Proteína rhoA de Ligação ao GTP/genética , Proteínas Mutadas de Ataxia Telangiectasia/genética , Sequência de Bases , Antígenos CD58/genética , Biologia Computacional , DNA (Citosina-5-)-Metiltransferases/genética , DNA Metiltransferase 3A , Proteínas de Ligação a DNA/genética , Dioxigenases , Escherichia coli , Exoma/genética , Imunofluorescência , Células HEK293 , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Isocitrato Desidrogenase/genética , Dados de Sequência Molecular , Mutação de Sentido Incorreto/genética , Proteínas Proto-Oncogênicas/genética , Análise de Sequência de RNARESUMO
Acute lymphoblastic leukemia (ALL) is an aggressive hematological tumor resulting from the malignant transformation of lymphoid progenitors. Despite intensive chemotherapy, 20% of pediatric patients and over 50% of adult patients with ALL do not achieve a complete remission or relapse after intensified chemotherapy, making disease relapse and resistance to therapy the most substantial challenge in the treatment of this disease. Using whole-exome sequencing, we identify mutations in the cytosolic 5'-nucleotidase II gene (NT5C2), which encodes a 5'-nucleotidase enzyme that is responsible for the inactivation of nucleoside-analog chemotherapy drugs, in 20/103 (19%) relapse T cell ALLs and 1/35 (3%) relapse B-precursor ALLs. NT5C2 mutant proteins show increased nucleotidase activity in vitro and conferred resistance to chemotherapy with 6-mercaptopurine and 6-thioguanine when expressed in ALL lymphoblasts. These results support a prominent role for activating mutations in NT5C2 and increased nucleoside-analog metabolism in disease progression and chemotherapy resistance in ALL.