BACKGROUND: Chediak-Higashi syndrome (CHS) is a rare, autosomal, recessive 
lysosomal disorder with hematological and immunologic abnormalities; however, 
stem-cell transplantation from a matched or related donor may be curative. Many 
mutations of the CHS1/LYST gene have been reported to date. We report a novel 
nonsense mutation of the CHS1/LYST gene in 3 Omani patients.
METHODS AND RESULTS: Three patients from 2 different families presented with 
clinical and laboratory features of CHS and a history of death of a previous 
sibling because of a severe illness, suggestive of the accelerated phase of CHS. 
Giant granules were present in the myeloid cell lines. Before the stem-cell 
transplant, the first patient underwent gene sequencing of all exons of the 
lysosome trafficking regulator (CHS1/LYST) gene and revealed a nonsense mutation 
in exon 5 (c.925C>T, p.R309X). Subsequently, upon presentation, the second and 
third patients' direct gene sequencing of exon 5 revealed the same mutation.
CONCLUSIONS: We report a nonsense mutation in exon 5 (c.925C>T, p.R309X). This 
supports the allelic heterogeneity of CHS and is in line with most reported 
mutation types that lead to a truncated protein. Identification of the mutation 
type will facilitate timely diagnosis, management, and family counseling for 
those with affected children in Oman.