Donor-type bone marrow aplasia following hematopoietic stem cell transplantation in a child with a novel SAMD9L variant

Pathogenic variants in the genes SAMD9 (sterile a-motif domain containing protein - 9) and SAMD9L (SAMD9-like) cause bone marrow failure with characteristic syndromic features. We report a case of a previously healthy, 3-year-old boy with no dysmorphology, who presented with severe aplastic anemia and a novel variant in the SAMD9L gene. His father, elder brother and sister who harbored the same variant were completely healthy. In the absence of a matched unrelated donor, he underwent a stem cell transplant from his sister, a 10/10 match. Almost 2 years later he developed donor type aplasia and succumbed to an invasive fungal infection after a failed haplograft from his mother. This case highlights the pathogenicity of this previously undescribed germline variation of uncertain significance in the SAMD9L gene and the value of comprehensive genetic testing for inherited bone marrow failures even in the absence of a positive family history or characteristic congenital abnormalities.