Fibrinogen Saint-Germain I: a case of the heterozygous Aalpha GLY 12 --> VAL fibrinogen variant.
A fibrinogen variant was suspected based on the results of routine coagulation tests in a 2-year-old asymptomatic child. Coagulation studies showed marked prolongation of both the thrombin and reptilase times, and discrepancy was noted between the level of plasma fibrinogen as measured by a kinetic versus immunological determination. Family studies revealed that the father beared the same abnormality. Studies of purified fibrinogen revealed an impaired release of both fibrinopeptides by thrombin. Fibrin monomer polymerization and fibrin stabilization were normal. DNA sequencing revealed a heterozygous G --> T point mutation in exon 2 of the gene coding for the Aalpha chain, which substituted a Gly for Val at position 12. Although the mutation is the same as in fibrinogen Rouen, fibrinogen Saint-Germain I shows a different fibrinopeptide release pattern and a mild factor V deficiency.
Mathonnet
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F
Laboratoire de biochimie et biologie moléculaire, Hôpital R Poincaré, Garches, France.
Peltier
J Y
JY
Detruit
H
H
de Raucourt
E
E
Alvarez
J C
JC
Mazmanian
G M
GM
de Mazancourt
P
P
D019943:Amino Acid Substitution; D002675:Child, Preschool; D020147:Coagulation Protein Disorders / Q000175:diagnosis* / Q000235:genetics; D004252:DNA Mutational Analysis; D003937:Diagnosis, Differential; D005166:Factor V Deficiency; D005192:Family Health; D005260:Female; D015241:Fibrinogens, Abnormal / Q000235:genetics*; D005344:Fibrinopeptide A / Q000032:analysis; D005345:Fibrinopeptide B / Q000032:analysis; D014644:Genetic Variation; D006579:Heterozygote; D006801:Humans; D017354:Point Mutation
D015241:Fibrinogens, Abnormal; C447420:fibrinogen Saint-Germain I; D005344:Fibrinopeptide A; D005345:Fibrinopeptide B