Summary
A 30-year-old female experienced three miscarriages in early pregnancy. Extensive
laboratory screening showed a low plasma fibrinogen level of approximately 1 g/l detected
by PT-derived fibrinogen assay.The fibrinogen level in the immunological assay was
3 g/l.The functional Clauss assay yielded an intermediate result of 1.78 g/l. During
her fourth and fifth pregnancy, the patient received fibrinogen concentrates (Haemocomplettan,
CLS Behring, Marburg, Germany), starting with 4 grams of human fibrinogen, followed
by 2 grams every second day until the 15th week of pregnancy.The further course of
these pregnancies was uneventful. SDS-PAGE and immunoblotting showed doublet bands
in the positions of the high-molecular weight (HMW)-and lowmolecular-weight (LMW)-fibrinogen,
a single LMW’ fibrinogen band, plus additional bands with higher molecular weight
than HMW-fibrinogen, which were also reactive with anti-human serum albumin (HSA)
antiserum. These bands correspond to variant fibrinogen conjugated with albumin. Reduced
SDS-PAGE and immunoblotting using polyclonal anti-fibrinopeptide A antiserum disclosed
one additional Aα-chain band with lower molecular weight. Amplification and sequencing
of exon 5 of the α gene indicated heterozygosity for a novel single nucleotide deletion
at codon Aα494 (C1537delA). His494 is replaced by Pro and this is followed by 23 (LMKLPSSTLPQLEKHSQ
VSSHLC) new amino acids before premature truncation after Cys517, yielding a free
C-terminal cysteine, which may link with albumin.This new fibrinogen mutation, leads
to a balanced array of homo- and heterodimeric fibrinogen molecules, some of which
are conjugated to albumin.
Keywords
Fibrinogen - dysfibrinogenemia - pregnancy complications - recurrent abortions