Homozygous mutation in CSF1R causes brain abnormalities, neurodegeneration, and dysosteosclerosis (BANDDOS).

Introduction: The CSF1R gene encodes the receptor for colony-stimulating factor-1, the macrophage, and monocyte-specific growth factor. Mutations in this gene cause hereditary diffuse leukoencephalopathy with spheroids (HDLS) with autosomal dominant inheritance and BANDDOS (Brain Abnormalities, Neurodegeneration, and Dysosteosclerosis) with autosomal recessive inheritance. Methods: Targeted gene sequencing was performed on the genomic DNA samples of the deceased patient and a fetus along with ten healthy members of his family to identify the disease-causing mutation. Bioinformatics tools were used to study the mutation effect on protein function and structure. To predict the effect of the mutation on the protein, various bioinformatics tools were applied. Results: A novel homozygous variant was identified in the gene CSF1R, c.2498C>T; p.T833M in exon 19, in the index patient and the fetus. Furthermore, some family members were heterozygous for this variant, while they had not any symptoms of the disease. In silico analysis indicated this variant has a detrimental effect on CSF1R. It is conserved among humans and other similar species. The variant is located within the functionally essential PTK domain of the receptor. However, no structural damage was introduced by this substitution. Conclusion: In conclusion, regarding the inheritance pattern in the family and clinical manifestations in the index patient, we propose that the mentioned variant in the CSF1R gene may cause BANDDOS.