Diamond-Blackfan anemia (DBA) is an inherited bone marrow failure syndrome 
characterized by anemia, congenital abnormalities, and cancer predisposition. 
Small ribosomal subunit genes RPS19, RPS24, and RPS17 are mutated in 
approximately one-third of patients. We used a candidate gene strategy combining 
high-resolution genomic mapping and gene expression microarray in the analysis 
of 2 DBA patients with chromosome 3q deletions to identify RPL35A as a potential 
DBA gene. Sequence analysis of a cohort of DBA probands confirmed involvement 
RPL35A in DBA. shRNA inhibition shows that Rpl35a is essential for maturation of 
28S and 5.8S rRNAs, 60S subunit biogenesis, normal proliferation, and cell 
survival. Analysis of pre-rRNA processing in primary DBA lymphoblastoid cell 
lines demonstrated similar alterations of large ribosomal subunit rRNA in both 
RPL35A-mutated and some RPL35A wild-type patients, suggesting additional large 
ribosomal subunit gene defects are likely present in some cases of DBA. These 
data demonstrate that alterations of large ribosomal subunit proteins cause DBA 
and support the hypothesis that DBA is primarily the result of altered ribosomal 
function. The results also establish that haploinsufficiency of large ribosomal 
subunit proteins contributes to bone marrow failure and potentially cancer 
predisposition.