A de novo nonsense variant in RPS10 causes Diamond-Blackfan anaemia in an Indian patient: clinical and functional evidence.

Diamond-Blackfan anaemia (DBA) is a rare inherited disorder marked by early-onset macrocytic anaemia and erythroid hypoplasia, resulting from mutations in ribosomal protein genes. Despite growing genetic insights, data on functional validation remain limited in India; here we report a novel RPS10 mutation with functional validation and provide genotype-phenotype correlation by integrating our findings with all previously reported RPS10 variants. A clinically suspected Diamond-Blackfan anaemia (DBA) case was evaluated through haematological profiling, bone marrow examination, and erythrocyte adenosine deaminase (eADA) activity measurement. Whole exome sequencing (WES) was followed by Sanger sequencing to identify and validate a novel pathogenic variant. Gene expression of ribosomal and regulatory genes was analysed by quantitative RT-PCR, and rRNA processing analysis was carried out to assess functional impact. The proband presented with severe macrocytic anaemia, reticulocytopenia, and erythroid hypoplasia consistent with Diamond-Blackfan anaemia (DBA). Whole exome sequencing identified a novel heterozygous nonsense variant in RPS10 (c.206G > A; p.Trp69Ter), and Sanger sequencing confirmed the variant as de novo. Gene expression analysis revealed significant upregulation of TP53 and downregulation of RPS10 and GATA1, indicating ribosomal dysfunction and activation of the p53 pathway. Additionally, the rRNA processing defect validated the pathogenicity of the novel RPS10 variant. This study identifies a novel de novo nonsense variant in RPS10 associated with Diamond-Blackfan anaemia, with supporting functional evidence of haploinsufficiency and p53 pathway activation. These findings expand the mutational spectrum of RPS10 and underscore the diagnostic value of integrating genomic and functional analyses in rare haematological disorders, while also contributing to ongoing efforts to delineate genotype-phenotype correlations in DBA.