Novel TMPRSS6 mutations associated with iron-refractory iron deficiency anemia (IRIDA).
Mutations leading to abrogation of matriptase-2 proteolytic activity in humans are associated with an iron-refractory iron deficiency anemia (IRIDA) due to elevated hepcidin levels. In this paper we describe 12 IRIDA patients belonging to 7 unrelated families and identify 10 (9 novel) TMPRSS6 mutations spread along the gene sequence: 5 missense, 1 non sense and 4 frameshift. The frameshift and non sense mutations are predict to result in truncated protein lacking the catalytic domain. The causal role of missense mutations (Y141C, I212T, R271Q, S304L and C510S) is demonstrated by in silico analysis, their absence in 100 control chromosomes and the high conservation of the involved residues. The C510S mutation in the LDLRA domain in silico model causes an intra-molecular structural imbalance that impairs matriptase-2 activation. We also assessed the in vitro effect on hepcidin promoter and the proteolytic activity of I212T and R271Q variants demonstrating a reduced inhibitory effect for the former mutation, but surprisingly a normal function for R271Q which appears a silent mutation in vitro. Based on mRNA expression studies I212T could also decrease the total amount of protein produced, likely interfering with mRNA stability. Collectively, our results extend the pattern of TMPRSS6 mutations associated with IRIDA and propose a model of causality for some of the novel missense mutation.
CEINGE, Centro di Ingegneria Genetica e Biotecnologie Avanzate, Via Comunale Margherita 482, Naples, Italy.
Luigia
L
De Falco
Francesca
F
Totaro
Antonella
A
Nai
Alessia
A
Pagani
Domenico
D
Girelli
Laura
L
Silvestri
Carmelo
C
Piscopo
Natascia
N
Campostrini
Carlo
C
Dufour
Fahd
F
Al Manjomi
Milen
M
Minkov
Dennis G
DG
Van Vuurden
Aurora
A
Feliu
Antonis
A
Kattamis
Clara
C
Camaschella
Achille
A
Iolascon
D018798:Anemia, Iron-Deficiency / Q000201:enzymology / Q000235:genetics*; D023181:Antimicrobial Cationic Peptides / Q000378:metabolism; D002648:Child; D002675:Child, Preschool; D004252:DNA Mutational Analysis; D004789:Enzyme Activation; D005260:Female; D016368:Frameshift Mutation / Q000235:genetics; D064451:Hepcidins; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D020125:Mutation, Missense / Q000235:genetics; D010375:Pedigree; D012697:Serine Endopeptidases / Q000235:genetics* / Q000378:metabolism
D023181:Antimicrobial Cationic Peptides; C578702:HAMP protein, human; D064451:Hepcidins; D008565:Membrane Proteins; D012697:Serine Endopeptidases; C504318:TMPRSS6 protein, human; C467801:matriptase 2