First allogeneic hematopoietic stem cell transplantation in RASGRP1 deficiency: long-term follow-up

Abstract

RAS guanyl-releasing protein 1 (RASGRP1) is a guanine-nucleotideexchange factor that is involved in lymphocyte development and function [1]. RASGRP1 converts the small GTPase RAS from an inactive GDP-bound state to an active GTP-bound state in response to lymphocyte activation. Activated RAS initiates a MAP-kinase cascade which leads to cytoskeletal reorganization and transcription of effector molecules [1, 2]. RASGRP1 deficiency was defined in human in 2016 [1]. It is shown to cause a combined type of primary immunodeficiency (PID) with susceptibility to Epstein-Barr virus infections [1]. Up to now, less than ten different cases of RASGRP1 deficiency have been defined [1–5]. The main clinical findings of patients include recurrent upper and lower respiratory infections, susceptibility to viral and opportunistic infections, hepatosplenomegaly, lymphadenopathy, EBV-associated lymphoproliferation, B cell lymphoma, and autoimmune features such as autoimmune cytopenia [1, 2, 4, 5]