Fibrinogen Hillsborough: a novel gammaGly309Asp dysfibrinogen with impaired clotting.
We present a novel gamma-chain dysfibrinogen that was discovered in a 32-year-old asymptomatic man admitted to the hospital after a car accident. He presented with a low fibrinogen concentration, 0.5 mg/mL, and a prolonged thrombin clotting time, 58 seconds. Analysis of purified fibrinogen by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed a gamma-chain variant with an apparently higher molecular weight. Isoelectric focusing (IEF) demonstrated an anodal shift in the banding pattern of the chains and electrospray ionization mass spectrometry (ESIMS) showed a 27-Da increase in the average mass of the unresolved variant and normal gamma chains. DNA sequence analysis showed a heterozygous mutation of GGC (Gly)-->GAC (Asp) at codon 309 of the gamma chain gene. This Gly--> Asp substitution was consistent with the charge change shown by IEF as well as the mass change identified by ESIMS. Functional analysis revealed that thrombin-catalyzed polymerization occurred with a longer lag time, lower rate of lateral aggregation, and similar final turbidity compared to normal and that factor XIII cross-linking was normal. The polymerization results suggest that residue gamma309 is necessary for proper alignment of fibrinogen molecules, specifically in protofibril formation and D:D interactions. gammaGly309 is highly conserved and x-ray structures support the conclusion that the lack of a side chain at this position helps facilitate the close contact between abutting gammaD domains of condensing fibrin monomers during polymerization.
Mullin
Jennifer L
JL
Molecular Pathology Laboratory, Canterbury Health Laboratories, Christchurch Hospital, Christchurch, New Zealand. jennifer.mullin@chmeds.ac.nz
Brennan
Stephen O
SO
Ganly
Peter S
PS
George
Peter M
PM
D000328:Adult; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D001224:Aspartic Acid / Q000235:genetics; D001704:Biopolymers / Q000096:biosynthesis; D001777:Blood Coagulation / Q000235:genetics*; D015241:Fibrinogens, Abnormal / Q000737:chemistry / Q000235:genetics* / Q000502:physiology*; D005998:Glycine / Q000235:genetics; D006801:Humans; D008297:Male; D008958:Models, Molecular; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009154:Mutation; D021122:Protein Subunits; D017386:Sequence Homology, Amino Acid; D013917:Thrombin / Q000494:pharmacology
D001704:Biopolymers; D015241:Fibrinogens, Abnormal; D021122:Protein Subunits; D001224:Aspartic Acid; D013917:Thrombin; D005998:Glycine