Tehran University of Medical Sciences Immunology and Genetics Journal 2645-4831 7 2 2024 06 22 82 86 Mostafa Kamali Network of Immunity in Infection, Malignancy and Autoimmunity (NIIMA), Universal Scientific Education and Research Network (USERN), Tehran, Iran Sepideh Shahkarami Department of Pediatrics, Dr. von Hauner Children's Hospital, University Hospital, Ludwig-Maximilians-Universität München (LMU), Munich, Germany; Medical Genetics Network (MeGeNe), Universal Scientific Education and Research Network (USERN), Munich, Germany Elham Rayzan Research Center for Immunodeficiencies, Children’s Medical Center, Tehran University of Medical Sciences, Tehran, Iran; International Hematology/Oncology of Pediatrics Experts (IHOPE), Universal Scientific Education and Research Network (USERN), Tehran, Iran. Iraj Mohammazadeh Noncommunicable Pediatric Diseases Research Center, Amirkola Hospital, Babol University of Medical Sciences, Babol, Iran Meino Rohlfs Department of Pediatrics, Dr. von Hauner Children's Hospital, University Hospital, Ludwig-Maximilians-Universität München (LMU), Munich, Germany Christoph Klein Department of Pediatrics, Dr. von Hauner Children's Hospital, University Hospital, Ludwig-Maximilians-Universität München (LMU), Munich, Germany Nima Rezaei Network of Immunity in Infection, Malignancy and Autoimmunity (NIIMA), Universal Scientific Education and Research Network (USERN), Tehran, Iran; Research Center for Immunodeficiencies, Children’s Medical Center, Tehran University of Medical Sciences, Tehran, Iran; Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran 2025 01 08 2025 01 12 Background: Griscelli syndrome type II is a primary immunodeficiency disorder caused by RAB27A gene mutation and is inherited in an autosomal recessive manner and characterized by oculocutaneous hypopigmentation and various cellular immune system deficiencies. Case Presentation: Herein, we report a 5-year-old girl with silvery-gray hair, eyebrows, and eyelashes who were referred to our primary immune deficiency clinic because of recurrent oral thrush. Further investigations were performed to uncover the probable underlying genetic disorder. Whole-exome sequencing revealed a novel mutation in the RAB27A gene (c.137T>G) and confirmed the diagnosis of Griscelli syndrome type 2. Conclusions: Due to the poor prognosis nature of this disorder and also its need for differential diagnosis with some other conditions with hypopigmentation, prompt diagnosis, genetic analysis, and proper treatment are necessary for avoiding serious complications. https://igj.tums.ac.ir/index.php/igj/article/view/163 https://igj.tums.ac.ir/index.php/igj/article/download/163/146