Mutations in the ribosomal protein (RP)S19 gene have been found in about 25% of 
the cases of Diamond-Blackfan anemia (DBA), a rare congenital hypoplastic anemia 
that includes variable physical malformations. Various mutations have been 
identified in the RPS19 gene, but no investigations regarding the effect of 
these alterations on RPS19 mRNA levels have been performed. It is well 
established that mutated mRNA containing a premature stop codon (PTC) or lacking 
a stop codon can be rapidly degraded by specific mechanisms called nonsense 
mediated decay (NMD) and nonstop decay. To study the involvement of such 
mechanisms in DBA, we analyzed immortalized lymphoblastoid cells and primary 
fibroblasts from patients presenting different kinds of mutations in the RPS19 
gene, generating allelic deletion, missense, nonsense, and nonstop messengers. 
We found that RPS19 mRNA levels are decreased in the cells with allelic deletion 
and, to a variable extent, also in all the cell lines with PTC or nonstop 
mutations. Further analysis showed that translation inhibition causes a 
stabilization of the mutated RPS19 mRNA. Our findings indicate that NMD and 
nonstop decay affect the expression of mutated RPS19 genes; this may help to 
clarify genotype-phenotype correlations in DBA.