| Autor: |
Tesi, Bianca, Davidsson, Josef, Voss, Matthias, Rahikkala, Elisa, Holmes, Tim D., Chiang, Samuel C.C., Komulainen-Ebrahim, Jonna, Gorcenco, Sorina, Rundberg Nilsson, Alexandra, Ripperger, Tim, Kokkonen, Hannaleena, Bryder, David, Fioretos, Thoas, Henter, Jan-Inge, Möttönen, Merja, Niinimäki, Riitta, Nilsson, Lars, Pronk, Cornelis Jan, Puschmann, Andreas, Qian, Hong, Uusimaa, Johanna, Moilanen, Jukka, Tedgård, Ulf, Cammenga, Jörg, Bryceson, Yenan T. |
| Zdroj: |
Blood; April 2017, Vol. 129 Issue: 16 p2266-2279, 14p |
| Abstrakt: |
Several monogenic causes of familial myelodysplastic syndrome (MDS) have recently been identified. We studied 2 families with cytopenia, predisposition to MDS with chromosome 7 aberrations, immunodeficiency, and progressive cerebellar dysfunction. Genetic studies uncovered heterozygous missense mutations in SAMD9L, a tumor suppressor gene located on chromosome arm 7q. Consistent with a gain-of-function effect, ectopic expression of the 2 identified SAMD9L mutants decreased cell proliferation relative to wild-type protein. Of the 10 individuals identified who were heterozygous for either SAMD9Lmutation, 3 developed MDS upon loss of the mutated SAMD9Lallele following intracellular infections associated with myeloid, B-, and natural killer (NK)–cell deficiency. Five other individuals, 3 with spontaneously resolved cytopenic episodes in infancy, harbored hematopoietic revertant mosaicism by uniparental disomy of 7q, with loss of the mutated allele or additional in cisSAMD9Ltruncating mutations. Examination of 1 individual indicated that somatic reversions were postnatally selected. Somatic mutations were tracked to CD34+hematopoietic progenitor cell populations, being further enriched in B and NK cells. Stimulation of these cell types with interferon (IFN)-α or IFN-γ induced SAMD9L expression. Clinically, revertant mosaicism was associated with milder disease, yet neurological manifestations persisted in 3 individuals. Two carriers also harbored a rare, in transgerm line SAMD9Lmissense loss-of-function variant, potentially counteracting the SAMD9Lmutation. Our results demonstrate that gain-of-function mutations in the tumor suppressor SAMD9Lcause cytopenia, immunodeficiency, variable neurological presentation, and predisposition to MDS with −7/del(7q), whereas hematopoietic revertant mosaicism commonly ameliorated clinical manifestations. The findings suggest a role for SAMD9L in regulating IFN-driven, demand-adapted hematopoiesis. |
| Databáze: |
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