Congenital Neutropenia With Specific Granulocyte Deficiency Caused By
Novel Double Heterozygous SMARCD2 Mutations: is there a benefit of
thrombopoietin receptor agonist therapy?
Abstract
SMARCD2 (SWI/SNF-related, matrix-associated, actin-dependent regulator
of chromatin, subfamily D, member 2) is critical for myelopoiesis.
Recently, bi-allelic SMARCD2 mutations have been reported in five
children causing autosomal recessive congenital neutropenia with
specific granulocytes deficiency (CN-SGD); a syndrome resulting in G-CSF
resistant neutropenia, recurrent infections and dysplastic myelopoiesis.
We report a new case with CN-SGD caused by two novel heterozygous
pathogenic variants in the SMARCD2 gene (c.1081del (p.Gln361Argfs*15),
and c.217C>T (p.Arg73*)). Treatment with weekly dosing of
thrombopoietin receptor agonist, Romiplostim, along with daily G-CSF
transformed her clinical course implying potential synergism. This
report advances understanding about CN-SGD caused by SMARCD2 mutations.