Molecular characterization of a factor VII deficient patient supports the importance of the second epidermal growth factor-like domain.
OBJECTIVE
Although a large number of gene mutations have been characterized in patients with factor VII (FVII) deficiency, few naturally occurring mutations have been described in epidermal growth factor (EGF)-like domains. We investigated a 6-year old Italian girl who had low functional and antigenic FVII plasma levels.


METHODS
Plasma levels of FVII activity and antigen were evaluated in the propositus and her relatives. Mutation screening was performed by sequencing the FVII gene. The effect of the identified FVII mutations was investigated by protein expression in transfected cells.


RESULTS
The propositus was shown to be a compound heterozygote for a known (Arg110Cys) and a novel (Asp123Tyr) missense mutation both occurring in the second EGF-like domain. In transfected cells, expression of the Arg110Cys mutation reduced the amount of intracellular and secreted FVII protein (48% and 18%, respectively). Likewise, cells transfected with the Asp123Tyr mutation gave rise to low intracellular (40%) and extracellular (4%) FVII antigen levels. In conditioned media, FVII procoagulant activity was reduced accordingly (10% and <1%, respectively).


CONCLUSIONS
Transient expression of the identified FVII mutations caused severely reduced but detectable FVII antigen and activity levels. The present findings suggest that the two naturally occurring missense mutations identified within the second EGF-like domain severely affect FVII protein handling, impairing the correct folding of FVII.
D'Andrea
Giovanna
G
Unità di Aterosclerosi e Trombosi, I.R.C.C.S. Casa Sollievo della Sofferenza, S. Giovanni Rotondo, Italy.
Bossone
Anna
A
Lupone
Maria Rosaria
MR
Peyvandi
Flora
F
Maisto
Giovanna
G
Perricone
Fabio
F
Grandone
Elvira
E
Margaglione
Maurizio
M
D000818:Animals; D001483:Base Sequence; D019556:COS Cells; D002522:Chlorocebus aethiops; D017931:DNA Primers; D004815:Epidermal Growth Factor / Q000235:genetics*; D005167:Factor VII / Q000235:genetics* / Q000378:metabolism; D005168:Factor VII Deficiency / Q000097:blood / Q000235:genetics*; D006801:Humans; D020125:Mutation, Missense; D017510:Protein Folding; D014162:Transfection
D017931:DNA Primers; D004815:Epidermal Growth Factor; D005167:Factor VII