Congenital afibrinogenemia: Mutations leading to premature termination codons in fibrinogen Aα-chain gene are not associated with the decay of the mutant mRNAs

Rosanna Asselta, Stefano Duga, Silvia Spena, Elena Santagostino, Flora Peyvandi, Gavino Piseddu, Roberta Targhetta, Massimo Malcovati, Pier O. Mannucci, Maria Luisa Tenchini

Research output: Contribution to journalArticle

Abstract

Congenital afibrinogenemia is a rare coagulation disorder with autosomal recessive inheritance, characterized by the complete absence or extremely reduced levels of fibrinogen in patients' plasma and platelets. Eight afibrinogenemic probands, with very low plasma levels of immunoreactive fibrinogen were studied. Sequencing of the fibrinogen gene cluster of each proband disclosed 4 novel point mutations (1914C>G, 1193G>T, 1215delT, and 3075C>T) and 1 already reported (3192C>T). All mutations, localized within the first 4 exons of the Aα-chain gene, were null mutations predicted to produce severely truncated Aα-chains because of the presence of premature termination codons. Since premature termination codons are frequently known to affect the metabolism of the corresponding messenger RNAs (mRNAs), the degree of stability of each mutant mRNA was investigated. Cotransfection experiments with plasmids expressing the wild type and each of the mutant Aα-chains, followed by RNA extraction and semiquantitative reverse-transcriptase-polymerase chain reaction analysis, demonstrated that all the identified null mutations escaped nonsensemediated mRNA decay. Moreover, ex vivo analysis at the protein level demonstrated that the presence of each mutation was sufficient to abolish fibrinogen secretion.

Original languageEnglish
Pages (from-to)3685-3692
Number of pages8
JournalBlood
Volume98
Issue number13
DOIs
Publication statusPublished - Dec 15 2001

ASJC Scopus subject areas

  • Hematology

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